Computer implemented method for generating working parameters of a printing apparatus, system, computer program and computer-readable medium thereof

Abstract

The invention relates to a computer implemented method (100) for automatically generating (GEN1) working parameters of a printing apparatus comprising a coating module, an ink support device and an ink rejuvenation device, the method (100) comprising: • Receiving at least one print quality score and / or at least one print quality metric, said print quality score and said print quality metric characterizing a print quality of a printed element printed by means of the printing apparatus, • Automatically generating (GEN1) adjusted working parameters of the coating module using said at least one print quality score and / or using said at least one print quality metric.

Description

[0001] COMPUTER IMPLEMENTED METHOD FOR GENERATING WORKING PARAMETERS OF A PRINTING APPARATUS, SYSTEM, COMPUTER PROGRAM AND COMPUTER-READABLE MEDIUM THEREOF

[0002] FIELD OF INVENTION

[0003] The present invention relates to a method for automatically generating working parameters of a printing apparatus.

[0004] The invention further relates to a system, a computer program and a computer readable medium thereof.

[0005] BACKGROUND OF INVENTION

[0006] A thermal transfer printer, or printing apparatus, is a machine that creates an image by melting ink from an ink donner film (ribbon) and by transferring selected parts of said melted ink at selective locations onto a thermal transfer image receiving sheet or material (substrate). Such printer usually comprises a print head and rollers to hold and unwind an inked ribbon onto rollers. In fact, in those types of printers, the ribbon is mounted onto a rigid core to be unwound during printing operation. The ink donor film therefore presents a limited length, comprises two ends and shall be disposed after use. Handling such ribbon is eased thanks to the presence of the core.

[0007] An alternative class of printing apparatuses uses an endless ribbon continuously coated and exposed to a printhead. In such printing apparatuses, an endless ribbon is transported such that a part of said endless ribbon is exposed to the print head and another part of said endless ribbon is dedicated to an “ink rejuvenation operation” whereby a new homogenous and plain coated layer of ink can be applied to the endless ribbon. The non-printed ink remaining onto the endless ribbon after one print may then be recovered to renew the coated layer for a next print. Therefore, multiple print cycles I recoating cycles may be run without changing the endless ribbon. Such type of printer is described in patent applications WO2022 / 128946, WO2022 / 128941 and WO2022 / 128929.

[0008] For all types of printers, quality assessment of the printing is essential to ensure optimal readability or decoding for a user using an appropriate device, as well as to ensure the integrity of the information encoded within. Therefore, it is essential to verify that predefined print quality criteria are met. When this is not the case, a way to overcome the problem is to adjust parameters of the printing apparatus.

[0009] Such parameters can comprise parameters relative to the inked ribbon itself such as its dimensions or its mechanical properties, parameters relative to the ink layer, such as its thickness or its chemical composition, parameters relative to the configuration of the printing apparatus, such as a predetermined speed of a roller during printing operation, for example a drive roller, or the print head set-up.

[0010] Prior art solutions usually involve subjective assessment of printing, wherein the quality of prints is rated visually by an operator based on relevant print features. Those prior art methods have several drawbacks. A first drawback is that human assessment may lack precision, as it is based on a subjective appreciation of an operator, which could result in different print quality assessments affected to a same print depending on the operator. Another drawback of the prior art methods for print quality assessment is that they do not allow to evaluate not only the cause(s) of the poor printing quality (such as the component(s) of the printer responsible for it), but they also do not allow to quantify the influence of different parameters on the overall print quality. As a result, such prior art methods can lead to significative costs which are due to the time required to adjust parameters iteratively until a target quality is reached or due to the cost of replacing the printer to avoid for stopping printing operations for too long.

[0011] There are prior art documents describing methods for generating and / or adjusting printer parameters to improve print quality, such as patent applications US20230305763 and US20190212955.

[0012] However, the methods described in the prior art for print quality assessment are not suitable for generating adjusted parameters to improve the print quality of more complex printing apparatus, such as thermal transfer printing apparatus, such as the one described in patent application WO 2022 / 128929. One objective of the present invention is to provide a method, a system thereof, a computer program product thereof and a computer readable medium thereof to limit the precited drawbacks.

[0013] SUMMARY According to a first aspect, the invention relates to a computer implemented method for automatically generating working parameters of a printing apparatus comprising a coating module, an endless ribbon and an ink rejuvenation device, the method comprising:

[0014] • Receiving at least one print quality score and / or at least one print quality metric, said print quality score and said print quality metric characterizing a print quality of a printed element printed by means of the printing apparatus ;

[0015] • Automatically generating adjusted working parameters of the printing apparatus using said at least one print quality score and / or using said at least one print quality metric

[0016] One advantage of the invention is to allow to improve the quality of printing of a printing apparatus. Another advantage of the invention is to provide a method allowing for remote troubleshooting and / or remote calibrating of a printing apparatus.

[0017] Another advantage of the invention is to provide a method for precisely and efficiently determining parameters responsible for defects in printing.

[0018] In one embodiment, at least one print quality score and / or at least one print quality metric is generated using a human machine interface.

[0019] One advantage is to determine print quality indicators using input data provided by a user.

[0020] In one embodiment, at least one print quality score and / or at least one print quality metric is generated by processing a digitized image of the printed element.

[0021] One advantage is to calculate precisely at least one print quality score and / or at least one print quality metric.

[0022] In one embodiment, the method comprises:

[0023] • Receiving a digitized image of at least one printed element by means of a first communication interface, said digitized image comprising a plurality of digitized patterns distributed in a plurality of regions of interest ;

[0024] • Performing the following steps by means of at least one calculator: ■ Extracting at least one first value of interest from at least one region of interest among the plurality of regions of interest ;

[0025] ■ Calculating at least one print quality score and / or calculating at least one print quality metric by respectively:

[0026] I. Extracting at least one second value of interest distinct of the first value of interest and calculating said print quality score using the first value of interest and using the second value of interest and / or;

[0027] II. Calculating said print quality metric using the first value of interest and using at least one value of reference ;

[0028] One advantage is to improve the speed of process to generate the adjusted working parameters.

[0029] In one embodiment, the method comprises:

[0030] • Receiving a reference image comprising a plurality of reference patterns distributed in a plurality of reference regions of interest;

[0031] • Extracting the value of reference from at least one of said plurality of reference regions of interest;

[0032] • Calculating at least one print quality metric using the first value of interest and using the extracted value of reference the adjusted working parameters being automatically generated using said calculated at least one print quality metric.

[0033] One advantage is to generate the adjusted working parameters according to a predefined quality criterion.

[0034] In one embodiment, the method comprises a step of extracting a plurality of values of reference from the plurality of regions of interest to calculate a plurality of print quality metrics, the adjusted working parameters being generated using said calculated plurality of print quality metrics.

[0035] One advantage is to improve the accuracy of the generated adjusted working parameters. In one embodiment, the first value of interest and the second value of interest are extracted from a same region of interest of the plurality of regions of interest.

[0036] One advantage is to evaluate the print quality in a specific area of the digitized image.

[0037] In one embodiment, the method comprises a step of extracting a plurality of values of interest from at least two distinct regions of interest of the plurality of regions of interest, the adjusted working parameters being generated using said plurality of values of interest.

[0038] In one embodiment, the first value of interest and / or the second value of interest characterize a print quality of at least one digitized pattern located in at least one region of interest of the plurality of regions of interest from which said first value of interest and / or said second value of interest are extracted.

[0039] In one embodiment, at least one print quality score and / or at least one print quality metric comprises at least one of the following indicators a contrast indicator, a print coverage indicator, a periodicity indicator, an edge raggedness indicator, an edge blurriness indicator, a pinholes indicator, a defect indicator, a blackness indicator, a stripe indicator, a text readability indicator, a linear print resolution indicator, a barcode readability indicator, a height scaling indicator, a rotation indicator, a siemens star resolution indicator, a quick response code indicator.

[0040] In one embodiment, the method comprises calculating a plurality of print quality scores and calculating a plurality of print quality metrics and automatically generating the adjusted working parameters using said calculated plurality of print quality scores and said calculated plurality of print quality metrics.

[0041] One advantage is to improve the accuracy of the generated adjusted working parameters.

[0042] In one embodiment, the method comprises a step of extracting a plurality of image features from the digitized image, said plurality of image features at least comprising coordinates of at least one region of interest of the plurality of regions of interest.

[0043] One advantage is to allow to determine the position of the printed patterns on the digitized image. In one embodiment, the method comprises receiving the initial working parameters of the printing apparatus and the adjusted working parameters are generated using said initial working parameters.

[0044] In one embodiment, the method comprises automatically generating at least one predicted print quality score and / or at least one predicted print quality metric by means of a machine learning algorithm using at least one digitized image as input data of said machine learning algorithm.

[0045] In one embodiment, the machine learning algorithm is trained using a training dataset comprising a plurality of training print quality scores and / or using a plurality of training print quality metrics of a plurality of training digitized images of a plurality of training printed elements.

[0046] In one embodiment, the plurality of training digitized images used to train the machine learning algorithm are labelled according to an expected human rating of their print quality.

[0047] In one embodiment, the predicted quality score and the predicted print quality metrics are automatically generated by:

[0048] • receiving at least one digitized image of at least one printed element by means of a first communication interface, said digitized image comprising a plurality of digitized patterns distributed in a plurality of regions of interest;

[0049] • Performing the following steps by means of at least one calculator:

[0050] ■ Extracting at least one first value of interest of at least one digitized pattern among the plurality of digitized patterns from at least one region of interest among the plurality of regions of interest;

[0051] ■ Calculating at least one print quality score and / or calculating at least one print quality metric by respectively:

[0052] I. Extracting at least one second value of interest distinct of the first value of interest and calculating said print quality score using the first value of interest and using the second value of interest and / or, II. Calculating said print quality metric using the first value of interest and using at least one value of reference.

[0053] In one embodiment, the machine learning algorithm comprises a classifier and said machine learning algorithm is configured to perform a set of predefined rules for affecting at least one print quality class to the digitized image.

[0054] In one embodiment, the method comprises a step of automatically generating a command signal using the generated adjusted working parameters.

[0055] In one embodiment, the adjusted working parameters of the printing apparatus comprise at least one of the following parameters:

[0056] • a speed of at least one roller of a transporting system to transport an endless ribbon along a predefined path of said endless ribbon forming a loop and / or,

[0057] • at least one working parameter of a printhead and / or,

[0058] • at least one working parameter of a coating device and / or,

[0059] • a set temperature of a cooling device arranged to cool down a coated layer between a coating device and a printing zone and / or,

[0060] • a position of at least one drive roller in reference to the endless ribbon.

[0061] In one embodiment, the method comprises:

[0062] • printing a printed element on a printing support using the printing apparatus by:

[0063] ■ driving an endless ribbon of the printing apparatus along a predetermined path of said endless ribbon forming a loop;

[0064] ■ coating a first portion of a surface of the endless ribbon with a coating composition using a coating device of the printing apparatus;

[0065] ■ driving the printing support to a printing zone;

[0066] ■ transferring the coated coating composition from the endless ribbon to the printing support to print the printed element on said printing support using a printhead of the printing apparatus. wherein the received print quality score and / or print quality metric characterize a print quality of said printed element.

[0067] In one embodiment, the method comprises acquiring a digitized image of the printed element using an optical detection device, transmitting the digitized image to at least one calculator using the communication interface and automatically generating the adjusted working parameters by automatically processing the digitized image.

[0068] In one embodiment, the method comprises automatically generating a command signal using the generated adjusted working parameters.

[0069] In one embodiment, the method comprises automatically transmitting the command signal to the printing apparatus.

[0070] According to another aspect, the invention relates to a computer implemented method for automatically generating working parameters of a thermal transfer printing apparatus, the method comprising:

[0071] • Receiving at least one print quality score and / or at least one print quality metric, said print quality score and said print quality metric characterizing a print quality of a printed element printed by means of the thermal transfer printing apparatus ;

[0072] • Automatically generating adjusted working parameters of the thermal transfer printing apparatus using said at least one print quality score and / or using said at least one print quality metric

[0073] One advantage of the invention is to allow to improve the quality of printing using a thermal transfer printing apparatus.

[0074] Another advantage of the invention is to provide a method allowing for remote troubleshooting and / or remote calibrating of a thermal transfer printing apparatus.

[0075] According to another aspect, the invention relates to a system comprising at least one calculator, said system being configured to execute the steps of the method according to the first aspect of the invention. The system may comprise a communication interface to receive at least one print quality score and / or at least one print quality metric. Alternatively, or in addition, at least one print quality score and / or at least one print quality metric may be calculated using the calculator.

[0076] In one embodiment, the system comprises the printing apparatus.

[0077] In one embodiment, the printing apparatus is a thermal transfer printing apparatus.

[0078] In one embodiment, the printing apparatus comprises a printhead adapted to perform printing operation without contact between the printhead and the endless ribbon.

[0079] In one embodiment, the system comprises an optical detection device.

[0080] According to another aspect, the invention relates to a computer program product comprising instructions to cause the system to execute the method of the invention.

[0081] According to another aspect, the invention relates to a computer- readable medium having stored thereon the computer program.

[0082] According to another aspect, the invention relates to a computer implemented method for automatically generating working parameters of a printing apparatus comprising a coating module, an ink support device and an ink rejuvenation device, the method comprising:

[0083] • Receiving at least one print quality score and / or at least one print quality metric, said print quality score and said print quality metric characterizing a print quality of a printed element printed by means of the printing apparatus;

[0084] • Automatically generating adjusted working parameters of the coating module using said at least one print quality score and / or using said at least one print quality metric.

[0085] In one embodiment, the printing apparatus comprises at least one controller configured to control at least one component of the coating module, and further comprises a step of automatically adjusting at least one working parameter by means of said controller.

[0086] In one embodiment, at least one generated adjusted working parameter comprises the thickness of an ink layer applied onto the ink support device.

[0087] In one embodiment, at least one generated adjusted working parameter comprises a speed of the ink support device. In one embodiment, the printing apparatus further comprises at least one support element to support the ink support device on an inner face of said ink support device.

[0088] In one embodiment, the coating module comprises a squeeze ink roller and an active element to press said squeeze ink roller onto an outer face of the ink support device, and the adjusted parameter of the coating module comprise at least one pressure parameter related to a pressure applied by said active element to said squeeze ink roller.

[0089] In one embodiment, at least one print quality score and / or at least one print quality metric is generated using a human machine interface.

[0090] In one embodiment, at least one print quality score and / or at least one print quality metric is calculated by processing a digitized image of the printed element

[0091] In one embodiment, at least one print quality metric is calculated by processing the digitized image of the printed element and by processing a reference image of a printed element.

[0092] In one embodiment, the method comprises:

[0093] • Receiving a digitized image of at least one printed element by means of a first communication interface, said digitized image comprising a plurality of digitized patterns distributed in a plurality of regions of interest;

[0094] • Performing the following steps by means of at least one calculator : o extracting at least one first value of interest from at least one region of interest among the plurality of regions of interest; o calculating at least one print quality score and / or calculating at least one print quality metric by respectively: o extracting at least one second value of interest distinct of the first value of interest and calculating said print quality score using the first value of interest and using the second value of interest and / or; o calculating said print quality metric using the first value of interest and using at least one value of reference.

[0095] In one embodiment, the method further comprises:

[0096] • Receiving a reference image comprising a plurality of reference patterns distributed in a plurality of reference regions of interest ;

[0097] • Extracting the value of reference from at least one of said plurality of reference regions of interest ;

[0098] • Calculating at least one print quality metric using the first value of interest and using the extracted value of reference, the adjusted working parameters being automatically generated using said calculated print quality metric.

[0099] In one embodiment, the method comprises a step of extracting a plurality of values of reference from the plurality of regions of interest to calculate a plurality of print quality metrics, the adjusted working parameters being generated using said calculated plurality of print quality metrics.

[0100] In one embodiment, the first value of interest and the second value of interest are extracted from a same region of interest of the plurality of regions of interest.

[0101] In one embodiment, the method comprises extracting a plurality of values of interest from at least two distinct regions of interest of the plurality of regions of interest, and wherein the adjusted working parameters are generated using said plurality of values of interest

[0102] In one embodiment, the method comprises automatically generating at least one predicted print quality score and / or at least one predicted print quality metric by means of a machine learning algorithm using at least one digitized image as input data of said machine learning algorithm.

[0103] In one embodiment, the plurality of training digitized images used to train the machine learning algorithm are labelled according to an expected human rating of their print quality.

[0104] According to another aspect, the invention relates to a system comprising at least one calculator and at least one communication interface, said system comprising hardware means and / or software means to execute the steps of the computer implemented method. In one embodiment, the system further comprises at least one optical detection device to detect a printed element.

[0105] According to another aspect, the invention relates to a printing apparatus comprising a coating module, an ink support device and an ink rejuvenation device, and comprising a calculator configured to execute any of the steps of the method.

[0106] In one embodiment, the printing apparatus further comprises at least one support element to support the ink support device on an inner face of said ink support device.

[0107] In one embodiment, the coating module further comprises a squeeze ink roller and an active element to press said squeeze ink roller onto an outer face of the ink support device.

[0108] According to another aspect, the invention relates to a computer program product comprising instructions to cause the system according to execute the steps of the method.

[0109] According to another aspect, the invention relates to a computer- readable medium having stored thereon the computer program.

[0110] BRIEF DESCRIPTION OF FIGURES

[0111] Fig. 1 is a schematic sectional view of a printing apparatus wherein the frame is not represented.

[0112] Fig. 2 is a schematic view of a system according to one aspect of the invention wherein the system comprises an optical detection device to detect and capture a printed element.

[0113] Fig. 3 is a schematic view of a digitized image comprising one digitized representation of a printed element, wherein the printed element is a printed label, and comprising a plurality of digitized printed patterns distributed in a plurality of regions of interest.

[0114] Fig. 4 is a schematic representation of a system of the invention according to one embodiment wherein the system comprises a printing apparatus, an optical detection device, a calculator, and a memory.

[0115] Fig. 5 is a schematic representation of steps of the method in one embodiment wherein the method comprises a step of automatically generating a command signal using adjusted working parameters generated using a digitized image of a printed element. Fig.6 is a schematic representation of steps of the method in one embodiment wherein the method comprises a step of using a machine learning algorithm trained with training data comprising training print quality scores and training print quality metrics.

[0116] Fig.7 is a schematic representation of an example of hardware configuration of the system of the invention.

[0117] Fig.8 is a schematic representation of a printing apparatus according to one embodiment wherein the ink support device is a non-elastically deformable cylinder.

[0118] DETAILED DESCRIPTION

[0119] The invention will be better understood with the following specifications referring to the figures.

[0120] According to a first aspect, the invention relates to a computer implemented method 100 for automatically generating GENi adjusted working parameters Zadj of a printing apparatus 1._More precisely, the invention relates to a computer implemented method 100 for automatically generating GENi adjusted working parameters Zadj of a coating module 7 of a printing apparatus 1 that comprises said coating module 7, an ink support device 5, and an ink rejuvenation device.

[0121] The printing apparatus 1 may be a thermal transfer printing apparatus.

[0122] The printing apparatus 1 comprises an ink support device 5. The ink support device 5 may comprise an endless ribbon 5, such as a continuous loop of ribbon designed for multiple uses, unlike disposable ribbons used in traditional printing apparatuses.

[0123] Alternatively, the ink support device 5 may be a non-elastically deformable ink support device. In one example, the ink support device 5 comprises a curved support, for example a cylindrical support. The ink support device 5 may comprise a rigid material, such as, but not limited to, a metal, steel, aluminum, glass, or any suitable material or combination of materials.

[0124] Figure 8 illustrates an example of an embodiment of the printing apparatus 1 wherein the ink support device is a cylinder 5 connected to a motor (not represented) to drive said cylinder 5 in rotation around a predefined axis of rotation. The cylinder 5 comprises an outer surface to support ink. The rotation of the 5 cylinder conveys said outer surface from the coating module 7 to a printing zone, which comprises a medium to be printed, and back from the printing zone to the coating module 7 in a cyclic manner. The coating module 7 comprises the ink rejuvenation device and a coater. The printing apparatus 1 comprises a printhead 6 located at a distance from the printing zone. The printhead 6 transmits energy towards the printing zone. An inked portion of the cylinder 5 that passes through the printing zone receives the transmitted energy, causing ink to transfer from the outer surface of the cylinder 5 to the medium to be printed. The rotation of the cylinder 5 moves the portion of the cylinder 5 that received energy back to the coating module 7 where the remaining ink is recovered by the ink rejuvenation device and said portion is coated with new ink for another cycle. The printhead 6 transmits energy towards said portion of the cylinder 5 in various ways, for example, through a laser beam, or using any other technology adapted to remotely cause the ink to transfer from the outer surface of the cylinder 5 to the medium to be printed.

[0125] The ink support device 5 may comprise an inner face and an outer face.

[0126] The printing apparatus 1 may comprise a conveyor system to hold and move the ink support device 5 along a predefined path from a coating zone, where ink is applied to the ink support device 5, to a printing zone where printing operation on a support is performed, and from said printing zone to the coating zone in a cyclic manner. The conveyor system may comprise one or several support elements to hold the ink support device 5. For example, the conveyor system may comprise a plurality of rollers to hold the ink support device 5 on its inner face along the predefined path.

[0127] The printing apparatus 1 may comprise a motor to drive said plurality of rollers to move the ink support device 5 along the predefined path.

[0128] The coating module 7 may comprise the ink support device 5. The coating module may comprise the conveyor system.

[0129] The conveyor system may be a system adapted to rotate a cylinder in rotation around a predefined axis of rotation, such as the ink transport device illustrated in figure 8.

[0130] The coating module 7 may comprise a coater to coat the ink support device 5 with hot melted ink in the coating zone. The coating method of the coating module 7 could be chosen among all coating techniques available to the skilled person, such as but not limited to roll-coating or roll-printing, knifecoating, curtain-coating, dipping, roll-coating, spin-coating, spray coating, gravure coating, jet printing, flat or rotary screen printing, slot die...

[0131] The coating module 7 may comprise a reservoir assembly designed to hold hot melted ink thereon and to feed the coater with said hot melted ink.

[0132] The coating module 7 may comprise a squeeze ink roller to transport the hot melted ink on its circumferential surface, said squeeze ink roller comprises an outer layer made of elastic material. One advantage of the outer layer of the squeeze ink roller is to allow thin coating with any types of ink on the ink support device 5. The squeeze ink roller may be in contact with the ink in the reservoir.

[0133] The coating module 7 may comprise one or several controllers to control elements of the coating module 7, such as, but not limited to, a motor, a heater, a cooler, a squeezer. The controller may be configured to automatically control at least one element of the coating module 7 depending on settings of said controller.

[0134] Not limiting examples of controllers are given bellow.

[0135] The coating module 7 may comprise a pressure controller. In one example, the coating module 7 comprises an actuator and the pressure controller is configured to control the actuator for adjusting the pressure between the squeeze ink roller and the conveyor system to modify a pressure applied on ink between the squeeze ink roller and the ink support device 5 supported by the conveyor system along a coating zone.

[0136] The coating module 7 may comprise a speed controller. In one example, the speed controller comprises at least one motor and is configured to control said motor to adjust the speed of at least one roller, such as a first speed of roller of the conveyor system and / or a second speed of the squeeze ink roller, for example a tangential speed of said squeeze ink roller.

[0137] The coating module 7 may comprise an ink level controller. In one example, the coating module 7 comprises at least one level sensor and the ink level controller is configured to control the reservoir to adjust the level of ink.

[0138] The coating module 7 may comprise a heat controller. In one example, the coating module 7 comprises at least one heater and the heat controller is configured to control a heater adjust ink parameters, such as its temperature or its viscosity.

[0139] The coating module 7 may comprise a cooling system controller. In one example, the coating module 7 comprises at least one cooler, such as an air-cooling system comprising a fan, and the cooling system controller 7 may be configured to control the cooling system to adjust temperature of ink or temperature of components of the printing apparatus 1 .

[0140] The printing apparatus 1 may comprise at least one communication interface to receive a control signal generated using the adjusted working parameters Zadj, and at least one controller may be configured to automatically control at least one element of the coating module 7 in response to the reception of the control signal. The coating module 7 may comprise the communication interface.

[0141] The printing apparatus 1 comprises an ink rejuvenation system aims at re-applying unused or residual ink back onto the ink support device 5 after it has passed through the printhead, allowing for the continuous reuse of ink support device 5 by recovering and re-coating ink onto it for future print cycles.

[0142] The printing apparatus 1 may comprise a printhead. The printhead may be separated from the coating module 7.

[0143] The printing apparatus 1 may comprise a calculator configured to perform the steps of the method of the invention. The calculator may be configured to generate a command signal to command at least one controller in response to the reception or the calculation of the adjusted working parameters Zadj.

[0144] The coating module 7 may comprise the calculator. The calculator may also be a distant entity configured to generate a distant signal and to automatically send it to the printing apparatus 1 that receives it through the communication interface.

[0145] The printing apparatus 1 may comprise various sensors, such as pressure sensors, speed rotation sensors, temperature sensors, ink level sensors, optical sensors, viscosity sensors.

[0146] The invention is described through several embodiments in reference to the figures. The examples described for one embodiment may be directly applicable to another embodiment if compatible. The invention protects the different combinations of features described through all the embodiments.

[0147] For brevity, the computer implemented method 100 is referred to as “the method” in the following description.

[0148] In the present description, we refer to a “printed element 25”. The printed element 25 may comprise a label, an electronic card, a plastic film or any other printing support adapted for printing at least one printed pattern Dpi, Dpn.

[0149] As such, the printed patterns Dpi, .... Dpnmay comprise geometrical shapes, barcodes, QR-codes, conductive paths, decorative patterns, or any other printed element using a printing apparatus equipped with an ink support device 5, such as, an endless ribbon 5, a coating module 7 and an ink rejuvenation device.

[0150] Metrics / score

[0151] The method 100 comprises a step of receiving at least one print quality score Sci and / or at least one print quality metric Pm i.

[0152] The received print quality score Sci and / or print quality metric Pmi characterize a print quality of at least one printed portion of a printed element 25 printed by means of the printing apparatus 1 .

[0153] It should be understood by “characterize a print quality of at least one printed portion of a printed element” that the received score(s) Sci and / or metric(s) Pmi may characterize a print quality in at least one given area of interest of the printed element 25.

[0154] For example, a print quality score Sci and / or a print quality metric Pmi may characterize a print quality of a pattern or of a part of a pattern of the printed element 25. An example of a printed element 25 comprising a plurality of patterns is represented on figure 3. Such patterns are called “printed patterns Dpi, ... , Dpx” in the present description.

[0155] A print quality score Sci refers to an indicator of print quality in at least one area of the printed element 25 determined using information from said printed element 25, or using information determined from a digitized representation of said printed element 25.

[0156] A print quality metric Pmi refers to an indicator of print quality in at least one area of the printed element 25 determined using information from said printed element 25 and using information from a reference, such as an element of reference or a digitized representation of an element of reference, for example a label of reference meeting expected criteria of print quality.

[0157] At least one print quality score Sci and / or print quality metric Pmi may comprise a value, a letter, or any other representation allowing to rate a print quality of the printed element 25.

[0158] At least one print quality score Sci and / or at least one print quality metric Pmi may be received through a communication interface from a local device. It should be understood by “a local device” a device part of the computer on which is performed the method 100, or a device connected through physical means to the computer. The local device may comprise a storage device, such as an internal or external memory, or any other storage device physically connected to the computer, or part of the computer.

[0159] In one embodiment, the reception of at least one print quality score Sci and / or at least one print quality metric Pmi comprises calculating at least one of said at least one one print quality score Sci and / or print quality metric Pmi. At least one print quality score Sci and / or print quality metric Pmi may be calculated locally, for example using a calculator connected to the computer or part of the computer on which is performed the method 100.

[0160] In addition, or alternatively, at least one print quality score Sci and / or at least one print quality metric Pmi may be calculated at least partially on a remote equipment. In such a case, the at least one print quality score Sci and / or at least one print quality metric Pmi may be received through the communication interface after being transmitted by the remote equipment. For example, the remote equipment and the computer may be connected to a server through a data network in order for the computer to receive data from the remote equipment. In addition, or alternatively, the remote equipment and the computer may be connected through a wireless link, for example via a Bluetooth connection, a wi-fi connection, a 4G or 5G connection, or via any other type of wireless connection adapted for data transmission / reception.

[0161] The remote equipment may comprise a user interface, for example a digital user interface.

[0162] One advantage is to allow for a user to send data remotely in a context of customer support. For example, if a customer encounters problems while printing with a printing apparatus, for example a thermal transfer printing apparatus or a printing apparatus adapted to perform printing without contact between the printhead and the ink support device 5, such as an endless ribbon or a curved support, for example a continuous cylindrical shape, it would allow him to send data remotely, which could comprise data relative to the printing such as an image of the print, or data relative to the printing apparatus such as working parameters of the printing apparatus, or at least one print quality score Sci and / or print quality metric Pmi. Thus, in such a case, the method would allow to generate new working parameters for the printing apparatus, and therefore to provide customer assistance in a context of remote troubleshooting or remote calibration.

[0163] In one embodiment, at least one print quality score Sa and / or at least one print quality metric Pmi is generated by means of a human machine interface. The human machine interface may comprise a pointing device, such as a computer mouse or a stylus, a keyboard, or any other device adapted for information entry from a user. The human machine interface may also comprise a touch screen.

[0164] At least one print quality score Sa and / or at least one print quality metric Pmi may be generated using a user’s input data. The user’s input data may comprise values, such as values calculated using a element 25 printed by means of the printing apparatus 1 . The user’s input data may also comprise parameters, such as parameters of the printing apparatus 1 , for example parameters characterizing a state of the printing apparatus 1 during printing operation of the printed element 25.

[0165] At least one print quality score Sa and / or at least one print quality metric Pmi generated by means of a human machine interface may be received by a calculator configured to perform the steps of the method 100 of the invention.

[0166] As a result, the invention allows to automatically generate adjusted working parameters Zadj of a printing apparatus 1 using at least one print quality score Sa and / or at least one print quality metric Pmi which can be calculated at least partially remotely and sent to the calculator configured to execute the steps of the method 100. At least one print quality score Sa and / or at least one print quality metric Pmi may also be calculated using the calculator configured to perform the steps of the method 100 of the invention. One advantage is to provide a method allowing to perform remote troubleshooting and / or remote calibrating on printing apparatuses, such as a thermal transfer printing apparatus or a printing apparatus adapted to perform printing without contact between the printhead and the ink support device 5, such as an endless ribbon.

[0167] In one embodiment, at least one print quality score Sci and / or at least one print quality metric Pmi is used to determine a set-up for the ink support device 5.

[0168] For example, at least one print quality score Sci and / or at least one print quality metric Pmi may be used to determine the speed of the ink support device 5, or a need for speed adjustment of the ink support device 5 to improve print quality.

[0169] In one embodiment, at least one print quality score Sci and / or at least one print quality metric Pmi is used to automatically to determine a setup for the coating module 7.

[0170] For example, at least one print quality score Sci and / or at least one print quality metric Pmi may be used to automatically determine an ink thickness applied on the ink support device 5..

[0171] Digitized image

[0172] In one embodiment, in reference to figure 5, the method 100 comprises a step of receiving RECi a digitized image 110 of at least one printed element 25 by means of a first communication interface 111.

[0173] The digitized image 110 may be received RECi from an external device.

[0174] An “external device” refers to a device external to the computer on which are performed the step of the method of the invention.

[0175] The external device may comprise a digitizing apparatus, for example a scanner, such as a tabletop scanner.

[0176] The external device may be connected to the computer through the first communication interface 111 in such a way that the external device can transmit data to the computer, for example data comprising the digitized image 110 after a digitizing operation and / or data previously stored in a memory 113 of the external device. The external device may comprise a scanning device, such as a high-resolution scanner, for example a scanner with a resolution equal to 2000 dots per inch, or higher.

[0177] The external device may also comprise any other type of scanning devices and / or any optical image acquiring devices, for example a high- resolution camera.

[0178] One advantage is to improve robustness in detection of features of the digitized image 110, such as patterns.

[0179] Another advantage is to obtain a digitized image 110 with optimal quality to improve precision of the quality assessment.

[0180] The external device may also comprise any other device comprising a memory 113 to store the digitized image 110.

[0181] The digitized image 110 may also be received RECi from the same device as the one on which is performed the method 100. For example, the digitized image 110 may be received through the communication interface 111 from a local memory 113 on which the digitized image 110 has been previously stored.

[0182] In one embodiment, the digitized image 110 is received through the communication interface 111 after being transmitted from a remote equipment,

[0183] In one embodiment, the method 100 comprises a step of automatically adjusting parameters of the external device. The parameters may be adjusted before digitizing the printed element 25. The adjusted parameters may comprise resolution, image type, image size, histogram adjustment, illumination adjustment.

[0184] In one embodiment, the method 100 comprises a step of saving the digitized image 110 in a memory 113.

[0185] In one embodiment, the method 100 comprises a step of converting the digitized image 110 from a first format to a second format. The format may comprise a tagged image file format image, or a multi tagged image format image.

[0186] In one embodiment, the method 100 comprises a step of automatically configuring the external device with an automatic scan mode. The configuration may comprise a predefined or configurable scan time inferior to a predefined threshold, for example ten seconds. The communication interface 111 may be connected to the external device. The communication interface 111 may comprise a physical link, such as a cable to link the computer and the external device, or a wireless link such as a Bluetooth or Wi-Fi link allowing data exchange between the computer and the external device.

[0187] The communication interface 111 may also allow communication between components of the computer on which is performed the method 100.

[0188] For example, the communication interface 111 may allow data exchange with a memory 113 of the computer to load the digitized image 110 from said memory 113.

[0189] In one embodiment, the method 100 comprises a step of digitizing at least one physical support 150 on which is arranged at least one printed element 25.

[0190] The physical support 150 may comprise a thermal transfer image receiving sheet. An example of a such thermal transfer image receiving sheet comprise a paper sheet with an A4 format.

[0191] The receiving step RECi may comprise digitization of the physical support 150.

[0192] In one illustrative example, the digitized image 110 is received RECi during digitization of at least one printed element 25 arranged on a physical support 150 comprising a thermal transfer image receiving sheet on which are arranged said printed elements 25.

[0193] The printed elements 25 may also be digitized directly without using an additional physical support 150.

[0194] In one embodiment, the method comprises a step of receiving RECi a digitized image 110 of several printed elements 25.

[0195] The digitized image 110 may comprise digitized representations of the printed elements 25 arranged according to a predefined arrangement.

[0196] An example of predefined arrangement comprises a position of each digitized representations of the printed elements 25 relatively to each other.

[0197] Another example of predefined arrangement comprises a position of each printed element 25 relatively to edges of the digitized image 110.

[0198] In another example, the digitized image 110 comprises digitized printed elements 25 arranged in such a way that a center of each digitized printed element 25 is part of a same segment parallel to an edge of the digitized image 110. In this example, the edge of the digitized image 110 may correspond to a digitized representation of an edge of the physical support 150.

[0199] In one embodiment, the method 100 comprises a step of converting at least one printed element 25 into the digitized image 110 using a position of reference.

[0200] The position of reference may be determined using a position of at least one portion of a pattern of reference. Such portion may comprise at least one elementary unit of the pattern of reference.

[0201] The pattern of reference may comprise a digitized pattern Dpi, .... Dpncorresponding to a digital representation of a pattern of the printed element 25.

[0202] One example of a pattern of reference is a black bar. For example, an edge of the black bar may be used as a reference point to position a printed element 25.

[0203] Alternatively, or in addition, any other digitized pattern Dpi, .... Dpnmay be used as a pattern of reference.

[0204] In one embodiment, the method 100 comprises a step of extracting a plurality of image features Ifi, ... , Ifnfrom the digitized image 110. The plurality of image features Ifi , ... , lfnmay comprise coordinates xa, yaof at least one region of interest Rii , ... , Rin of the digitized image 110. At least one region of interest Rii , ... , Rin may comprise at least one digitized pattern Dpi , , Dpn.

[0205] In one embodiment, at least one printed element 25 is converted into the digitized image 110 according to a guided position.

[0206] For example, an alignment guide may be printed on the physical support 150 before digitization to ensure that the printed elements 25 are arranged at a predefined desired position.

[0207] In one embodiment, the method comprises a step of resizing and / or cropping the digitized image 110.

[0208] For example, the digitized image 110 may be cropped in order to isolate one printed element 25 from a plurality of printed elements 25.

[0209] In another example, the digitized image 110 may be cropped in order to isolate at least one digitized pattern Dpi, .... Dpnof a given printed element 25, or at least one portion of at least one digitized pattern Dpi, .... Dpn of at least one printed element 25. Such portion may comprise at least one elementary unit of the digitized pattern Dpi, .... Dpn.

[0210] One advantage is to reduce the amount of information in the digitized image 110 in order to reduce further image processing operations.

[0211] Another advantage is to improve the efficiency of further image processing operations.

[0212] Another advantage is to allow focusing on further processing operations or on one or several specific portions of the digitized image 110.

[0213] In one embodiment, the method comprises a step of associating at least one digitized representation of at least one printed element 25 of the digitized image 110 with an identifier. The identifier allows to identify a specific printed element 25 among a plurality of printed elements 25.

[0214] The identifier may comprise numbers, letters, or any other form of information allowing to distinguish the printed elements 25.

[0215] For example, in a case where the digitized image 110 comprises four digitized representations of four printed elements 25, the identifier of the second printed element 25 from the top of the digitized image 110 may be 2 / 4. The identifier may also comprise a numbering of the physical support 150 among a plurality of supports, such as a number of the digitized image 110 among a plurality of digitized images. For example, among a set of ten digitized images 110, four elements may be arranged on each image. The identifier may comprise the number of the digitized image 110, for example 1 / 10, as well as the number of the printed element 25, for example 2 / 4.

[0216] In one embodiment wherein the ink support device 5 comprises an endless ribbon, the digitized image 110 comprises an image negative of at least one portion of an endless ribbon 5 of the printing apparatus 1 . It should be understood as “an image negative” an image representative of a coated side of the endless ribbon 5 after printing. The image negative may represent a resulting coating state of the endless ribbon 5 after printing. Such representation of a resulting coating state of the endless ribbon 5 may comprise representations of a remaining ink arrangement on the surface of the ribbon and / or representations of a remaining ink quantity on the surface of the ribbon after printing operations. Thus, the image negative may be processed to determine the adjusted working parameters Zadj of the printing apparatus 1 . The image negative may be obtained by performing a set of mathematical operations on the digitized image 110 of the printed element 25.

[0217] In one embodiment, the image negative is obtained using an optical detection device. The optical detection device may be arranged in such a way that it can acquire an image of a remaining coated portion of the endless ribbon 5 after printing operation, and before said endless ribbon 5 is recoated for a new printing cycle.

[0218] Digitized patterns

[0219] In one embodiment, the received RECi digitized image 110 comprises a plurality of digitized patterns Dpi, .... Dpn. The digitized patterns Dpi, .... Dpnmay comprise digital representations of printed patterns of the printed element 25.

[0220] Each digitized pattern Dpi, .... Dpnmay comprise pattern features. The pattern features may comprise a geometrical shape such as vertical or horizontal lines, bars, circles, for example concentric circles, characters, such as numbers or letters, a specific combination of elements, such as a combination of letters and / or numbers, dimensions such as one or several lengths, a specific geometrical arrangement of elements, such as parallel bars or concentric circles, a specific sequence such as bars with increasing width from left to right or inversely, a position of the pattern relatively to a reference, such as a pattern or reference or a portion of a pattern used as a reference point, or any combination of the precited features.

[0221] In one embodiment, at least one digitized pattern Dpi, .... Dpncomprises lines with a thickness comprised between 0.1 mm and 0.5mm.

[0222] In one embodiment, at least one digitized pattern Dpi, .... Dpncomprises concentric circles with thickness comprised between 0.1 mm and 0.5mm.

[0223] In one embodiment, at least one digitized pattern Dpi, .... Dpncomprises a white area. The white area may correspond to a gap between two printed elements of a pattern, for example a white gap between two parallel vertical bars.

[0224] In one embodiment, at least one digitized pattern Dpi, .... Dpncomprises a barcode comprising encoded information. The encoded information may comprise parameters of a printing apparatus 1. In addition, or alternatively, at least one digitized pattern Dpi, .... Dpnmay comprise a barcode encoding information relative to the printed element 25 and / or parameters relative to an ink support device 5, such as an inked ribbon used to print the printed element 25.

[0225] In one embodiment, at least one digitized pattern 2500 comprises a bar gap repetition pattern arranged in horizontal and vertical directions.

[0226] Figure 3 illustrates an example of a digitized image 110 comprising a plurality of digitized patterns Dpi, .... Dpg.

[0227] The digitized patterns Dpi, ... , Dpnmay comprise several shapes of patterns, such as parallel bars of same length and variable width, concentric circles, full black bar, sequence of letters, parallel bars of same length forming a rectangle, horizontal barcode, siemens star shape, parallel bars of same length forming a square, vertical barcode.

[0228] The preceding list is not exhaustive and only aims at giving examples of digitized printed patterns that the digitized image 110 may comprise.

[0229] Figure 3 illustrates an example of a digitized image 110 comprising a plurality of digitized patterns Dpi , ... , Dpg.

[0230] In one embodiment, the method 100 comprises a step of labelling a plurality of digitized patterns Dpi, .... Dpn. The labelling step may allow to classify the digitized patterns Dpi , ... , Dpnthrough several categories.

[0231] The labelling step may be performed using pattern features. For example, the labelling step may be performed by calculating a probability score of detection of each pattern feature for each digitized pattern Dpi, .... Dpnand comparing the probability scores to a threshold value to confirm or infirm the detection of the features. A step of classification may be performed using the result of the comparison of the probability scores to a threshold value.

[0232] In addition, or alternatively, the digitized patterns Dpi, .... Dpnmay be labelled depending on a print quality parameter. The print quality parameter may comprise a value characteristic of the print quality and / or a value characteristic of a gap between a reference value.

[0233] In one embodiment, the digitized image 110 comprises at least one digitized pattern Dpi, .... Dpnencoding an identifier of the printed element 25. In one embodiment, the digitized image 110 comprises at least one digitized pattern 2500 encoding an identifier of the printing apparatus 1 used to print a printed element 25.

[0234] Digitized image: regions of interest

[0235] The digitized image 110 may comprise a plurality of regions of interest Rii , , Rin. The regions of interest Rii , , Rin can be defined as portions of the digitized image 110 comprising usable information.

[0236] The digitized patterns Dpi, .... Dpnof the printed element 25 may be distributed in the plurality of regions of interest Rii, ..., Rin.

[0237] At least one region of interest Rh, ..., Rin may comprise one or several digitized patterns Dpi, .... Dpn.

[0238] In addition, or alternatively, at least one region of interest Rii, ..., Rin may comprise at least one portion of at least one digitized pattern Dpi , ... , Dpn.

[0239] In one embodiment, at least one region of interest Rh, ..., Rin comprises at least one digitized pattern Dpi, .... Dpn.

[0240] In one embodiment, each region of interest Rii, ..., Rin comprises at least one digitized pattern Dpi, .... Dpn.

[0241] In one embodiment, at least one region of interest Rh, ..., Rin comprises a plurality of digitized patterns Dpi, .... Dpn.

[0242] In one embodiment, each region of interest Rii, ..., Rin comprises a plurality of digitized patterns Dpi, .... Dpn.

[0243] In one embodiment, at least one region of interest Rh, ..., Rin comprises a digitized pattern Dpi, .... Dpnbelonging to at least one other region of interest Rii, ..., Rin, or a portion of said digitized pattern Dpi, .... Dpn.

[0244] In one embodiment, at least one region of interest Rh, ..., Rin comprises a printed area that does not belong to a digitized pattern Dpi, .... Dpn. Such printed area may be related to a defect. Such printed area may result from a printing error.

[0245] In one embodiment, at least one region of interest Rh, ..., Rin comprises a non-printed area. A non-printed area at a specific location may be considered as useful information, for example if printing was expected in the non-printed area. For example, if the coordinates of the non-printed area are located in a pattern area or nearby, the non-printed area may be considered as a printing defect. In one embodiment, the method comprises a step of isolating at least one region of interest Rii , ..., Rin from the plurality of regions of interest Rii, ..., Rin.

[0246] In addition, or alternatively, at least one region of interest Rii, ..., Rin may comprise a non-printed area. For example, the absence of printing in a given area, or at a given position of the digitized image 110 may be considered as usable information.

[0247] In one embodiment, the method comprises a step of isolating at least one region of interest Rii , ..., Rin.

[0248] One advantage is to process information from a specific portion of the digitized image 110.

[0249] At least one region of interest Rh, ..., Rin may be isolated by selecting an area of the digitized image 110. For example, a user may select manually a region of interest Rii , ... , Rin in the digitized image 110, for example using a user interface, such as a digital screen, or a pointing device connected to the computer, such as a mouse.

[0250] In addition, or alternatively, at least one region of interest Rii, ..., Rin may be isolated using a searching algorithm.

[0251] The searching algorithm may be configured to detect specific features in the digitized image 110, such as shapes, for example rectangular contours.

[0252] The method 100 may comprise a step of receiving input data of the searching algorithm. The input data may comprise features characteristics of at least one digitized pattern such as dimensions, for example a size of a digitized pattern Dpi, .... Dpn. In addition, or alternatively, at least one input data of the searching algorithm may be calculated by extracting features from the digitized image 110.

[0253] The input data of the searching algorithm may comprise a constraint. The searching algorithm may be configured to automatically filter features of the digitized image 110 that do not match the constraint. For example, the input data may comprise a size of a specific pattern, such as the size of a black bar, and the searching algorithm may be configured to detect rectangular contours in the digitized image 110. In that example, the input data allow the algorithm to filter the rectangular contours which do not match the constraint required by the input data. In one embodiment, the method comprises a step of associating coordinates to at least one position in the digitized image 110. The coordinates may be associated with a portion of a digitized pattern Dpi, .... Dpn, for example a portion of a digitized pattern Dpi, .... Dpncomprised in a region of interest Rii , ..., Rin isolated using the searching algorithm, such as a corner of a black bar. The associated coordinates may comprise coordinates in a coordinate system, such as an orthonormal coordinate system defined by a length direction and a width direction of the digitized image 110. The associated coordinates may comprise origin coordinates in the coordinate system, such as (0,0).

[0254] In one embodiment, the digitized image 110 may be processed using an image processing algorithm. The image processing algorithm may be automatically performed. The image processing algorithm may be performed previous to isolating at least one region of interest Rii , ..., Rin. The processing algorithm may be configured to perform one or several steps among the following: down sampling the digitized image 110, binarize the digitized image 110.

[0255] In one embodiment, the method comprises a step of isolating at least one region of interest Rh, ..., Rin in the digitized image 110 using the coordinates associated to at least one position in the digitized image 110. For example, when origin coordinates (0,0) are associated with a given position in the digitized image 110, those coordinates may be used as a reference to determine one or several coordinates located in at least one other region of interest Rii , ..., Rin.

[0256] One advantage is to improve accuracy of the coordinates assignment by allowing an alternative to the use of a searching algorithm for each region of interest Rii , ..., Rin.

[0257] In one embodiment, the step of isolating Rh, ..., Rin at least one region of interest Rh, ..., Rin in the digitized image 110 comprises extracting said region of interest Rii, ..., Rin in the digitized image 110.

[0258] In one embodiment, the step of isolating ISO at least one region of interest Rh, ..., Rin in the digitized image 110 comprises selecting said region of interest Rii, ..., Rin in the digitized image 110.

[0259] Digitized image: calculation of the value of interest The method 100 may comprise a step of extracting EXTi at least one first value of interest Van from at least one region of interest among the plurality of regions of interest Rii , ..., Rin.

[0260] In one embodiment, the method 100 comprises a step of extracting EXT2 at least one second value of interest Vai2 distinct from the first value of interest Van from at least one region of interest among the plurality of regions of interest Rii, ..., Rin.

[0261] We distinguish the first value of interest Vaii from the second value of interest Vai2 as when a “print quality score” is calculated, at least two different values of interest extracted from the digitized image 110 may be used.

[0262] The first value of interest Van and / or the second value of interest Vai2 may comprise a value characteristic of an element located in a region of interest Rii , ..., Rin. The element may comprise a printed element, such as a digitized pattern Dpi, .... Dpnor a part of a digitized pattern Dpi, .... Dpn. The element may also comprise a non-printed element, such as a white gap between several printed areas, or a non-printed area.

[0263] The first value of interest Van and / or the second value of interest Vai2 may comprise a dimension. The dimension may be relative to a position of a digitized representation of at least one printed element 25 on the digitized image 110. The dimension may depend on a position of at least one digitized printed element 25 relatively to at least one another digitized representation of at least one other printed element 25 on the digitized image 110.The dimension may comprise a length, a width, a height, or an area. Examples of a first value of interest Van comprising a dimension comprise a length of a printed edge in a region of interest Rii , ..., Rin, a shore area or a border of an element in a region of interest Rii , ..., Rin, an area of pinholes in an element in a region of interest Rii , ..., Rin smaller than a given dimension, an area of defects in an element in a region of interest Rii, ..., Rin smaller than a given dimension, an ink coverage in a region of interest Rii , ..., Rin.

[0264] In addition, or alternatively, the first value of interest Van and / or the second value of interest Vai2 may comprise a resolution, such as a pixel intensity or a linear print resolution. Examples of values of interest Vai relative to a resolution comprise a pixel intensity in a digitized pattern Dpi, .... Dpn, a difference of pixel intensity between a printed area and a non-printed area of the digitized image 110. In one embodiment, the first value of interest Van and / or the second value of interest Vai2 comprise an average value. An example of a value of interest Vai comprising an average value comprises an average pixel intensity, for example along a predefined direction, for example a vertical direction.

[0265] In one embodiment, the first value of interest Van and / or the second value of interest Vai2 comprise a number of elements. For example, the first value of interest Van and / or the second value of interest Vai2 may comprise a number of pixels, such as a number of black pixels or a number of white pixels in a given region of interest Rii , ..., Rin.

[0266] In one embodiment, the first value of interest Van and / or the second value of interest Vai2 comprise a magnitude, for example the magnitude relative to the power spectral density at a given position in a printed area.

[0267] In one embodiment, the first value of interest Van and / or the second value of interest Vai2 are calculated using at least one feature extracted from at least one region of interest Rii, ..., Rin. The feature may comprise a dimension of an element and / or a resolution and / or an average value and / or a number of elements and / or a magnitude.

[0268] In one embodiment, the step of extracting the first value of interest Van and / or the second value of interest Vai2 comprise preprocessing at least one isolated region of interest Rii, ..., Rin. The preprocessing may be performed using an image processing algorithm.

[0269] Examples of preprocessing comprise binarization, application of a filter such as an edge filter, morphological operations such as returning all structures larger than an operator of a predefined size, using a Boolean operator such as an” and” operator, a thresholding operation, a computing operation such as computing a power spectral density of an element, using a peak detection algorithm, resizing operations, dividing operations such as dividing a region of interest Rii, ..., Rin. into several parts.

[0270] Reference image: calculation of reference value

[0271] In one embodiment, the method 100 comprises a step of receiving REC2 a reference image 210 comprising a plurality of reference patterns Dprefi , .... Dprefn distributed in a plurality of reference regions of interest Riren , Rirefn. In one embodiment, the reference image 210 comprises a reference pattern with a higher resolution than a digitized pattern Dpi, .... Dpnlocated in a region of interest Rh, .... Rin of the digitized image 110.

[0272] In one embodiment, the reference image 210 comprises a vectorial version of a reference pattern.

[0273] In one embodiment, the method comprises 100 a step of replacing at least one reference pattern with its vectorial version. This step may be performed using a vector graphics editor.

[0274] In one embodiment, the method comprises a step of calculating a value of reference Vn. The value of reference Vn may be calculated using the reference image 210. The value of reference Vn may be calculated using an element of the reference image 210, such as a printed element or a non-printed element such as a white gap between several printed areas, or a non-printed area.

[0275] The value of reference Vn may comprise a dimension. The dimension may comprise a length, a width, a height, or an area. Examples of values of reference Vn comprising a dimension comprise a length of a reference edge, a shore area of a reference element, a total area of an element such as a total area of a black bar, a total white gap area in the reference image 210, a reference ink coverage in the reference image 210, a height of an element in the reference image 210.

[0276] In addition, or alternatively, the value of reference Vn may comprise a resolution, such as a pixel intensity or a linear print resolution.

[0277] In one embodiment, the value of reference Vn comprises an average value.

[0278] In one embodiment, the value of reference Vn comprises a number of elements, for example a number of pixels, such as a number of blacks pixels or a number of white pixels in a given area of the reference image 210.

[0279] In one embodiment, the value of reference Vn comprises a magnitude, for example the magnitude relative to the power spectral density at a given position in a printed area in the reference image 210.

[0280] Calculation of print quality indicators: metrics and scores

[0281] In one embodiment, the method 100 comprises a step of calculating CLCi at least one print quality score Sci using the first value of interest Van and using the second value of interest Vai2 by means of at least one calculator 112.

[0282] Examples of print quality scores Sa comprise a rotation angle, a pinholes area percentage, a defect area percentage, a contrast, an average blackness, an average peak intensity, a periodicity, a text readability, a resolution such as a linear resolution or a siemens star resolution.

[0283] In one embodiment, at least one print quality score Sci is calculated CLCi by calculating a ratio between the first value of interest Van and the second value of interest Vai2. For example, at least one print quality score Sci may be calculated by dividing a number of black pixels in a region of interest Rii , .... Rin by a sum of said number of black pixels and of the white pixels in the same region of interest Rii, .... Rin.

[0284] In one embodiment, the method 100 comprising a step of calculating CLC2 at least one print quality metric Pmi using the first value of interest Van and using at least one value of reference Vn by means of at least one calculator 112.

[0285] Example of print quality metrics Pmi comprise a line length ratio, a shore area ratio, a coverage ratio, a height scaling.

[0286] At least one print quality score Sci and / or at least one print quality metric Pmi may be automatically calculated using an algorithm, such as an image processing algorithm applied to the digitized image 110, and / or applied to the reference image 210, and / or applied to one or several specific regions of interest of the digitized image 110 or the reference image 210.

[0287] In one embodiment, at least one print quality metric Pmi and / or at least one print quality score Sci is automatically calculated using at least one predefined rule. Different predefined rules may be implemented for calculating different each print quality score Sci and / or each print quality metric Pmi.

[0288] At least one predefined rule may comprise mathematical operations such as calculating a sum, a difference, a product, or a ratio, or using a mathematical function, such as a function which returns an area under curve.

[0289] At least one predefined rule may comprise a combination of mathematical operations using one or several values of interest VAI, such as the first value of interest Van and the second value of interest Vai2, and / or one or several values of reference VRL In one embodiment, at least one print quality metric Prrii is calculated CLC2 by calculating a ratio between a value of interest Vai and a value of reference Vn.

[0290] Examples of such ratio comprise a ratio between a dimension of a print feature and a dimension of a reference feature, such as a ratio between a length of a printed edge and a length of a reference edge, or such as a ratio between a height in the digitized image 110 and a height in the image of reference 210, a ratio between a specific area of a printed feature and a corresponding specific area of a reference feature, such as a ratio between shore areas or such as a ratio between ink coverage, a ratio between a specific area of a printed feature and a different specific area of a reference feature, such as a ratio between an area of pinholes smaller than a given size and a total area of a given pattern or a total area of a gap.

[0291] In one embodiment, at least one print quality score SG is calculated CLC1 by calculating a ratio using at least one value of interest Vai.

[0292] Examples of such ratio comprise calculating a ratio between one value of interest Vai and an integer. For example, a print quality score for quantifying how well gaps of the linear resolution targets are resolved may be calculated with value of interest VAi comprising a number of peaks calculated by applying a peak detection algorithm on an average profile of pixel intensities along a horizontal direction, wherein each peak corresponds to a line gap. This value of interest VAI may be divided by an integer, for example a number of expected gaps.

[0293] In another example, a text readability of a digitized pattern Dpi, .... Dpnmay be calculated using an algorithm returning and area under curve relative to an evolution of a ratio between an integer and a number of connected elements for varying thresholds.

[0294] The method may comprise a step of storing algorithm parameters in a file. The algorithm parameters may be stored in a file together with parameters of the digitized image 110, such as coordinates of the regions of interest Rh, .... Rin. The algorithm parameters and the parameters of the digitized image 110 may be loaded upon a framework launch, such as a python framework. Those parameters may be loaded together with the reference image 210 or parameters relative to said reference image 210. In one embodiment, the method comprises a step of extracting metadata from the digitized image 110. The metadata may be extracted by decoding a digitized pattern Dpi, .... Dpn, such as a barcode. The metadata may be extracted using a decoding algorithm. The metadata may comprise parameters related to the printing apparatus, parameters related to the printed element 25 and / or parameters related to an ink support device 5, such as an inked endless ribbon of the printing apparatus 1 .

[0295] In one embodiment, the calculated print quality scores Sci and / or the calculated print quality metrics Pmi are automatically stored in a file, for example a .csv file.

[0296] In one embodiment, the method 100 comprises a step of calculating CALCs a global print quality indicator GPki. The global print quality indicator GPki may correspond to a single printing assessment of the printed element 25. The global print quality indicator GPki may comprise a number indicating a print quality according to a predefined scale of rating. The global print quality indicator GPki is for example calculated by performing at least one predefined rule. The global print quality indicator GPki is for example calculated using the a plurality of print quality scores Sci and / or a plurality of print quality metrics Pmi.

[0297] Artificial intelligence

[0298] In one embodiment, the method comprises a step of automatically generating at least one predicted print quality score MSa and / or at least one predicted print quality metric M Pmi by means of a machine learning algorithm MLi using at least one digitized image 110 as input data of said machine learning algorithm MLi.

[0299] The predicted print quality score MSci and / or the predicted print quality metric MPmi may be generated by the machine learning algorithm MLi using a plurality of print quality scores SCi and / or using a plurality of print quality metrics Pmi.

[0300] In one embodiment, at least one predicted print quality indicator MLpki may be calculated using at least one predicted print quality score MSa and / or at least one predicted print quality metric MPmi.

[0301] The predicted print quality indicator MLpki may correspond to an expected human rating of the print quality of the printed element 25. For example, the predicted print quality indicator MLpki may correspond to an expected human rating of the print quality of the printed element 25 based on the plurality of print quality scores SCi and / or using a plurality of print quality metrics Pmi.

[0302] In one embodiment, the machine learning algorithm MLi comprises a classifier. The machine learning algorithm MLi may perform a classification of an input image, such as the digitized image 110, based on a plurality of print quality scores Sci and / or a plurality of print quality metrics Pmi. For example, the classifier may comprise several classes and the class in which the printed element 25 is classified may depend on a plurality of print quality scores Sci and / or a plurality of print quality metrics Pmi. The classes may correspond to a plurality of predicted print quality indicator MLpki. Each class may correspond to a printing quality, for example an insufficient quality or a perfect quality.

[0303] In one embodiment, the machine learning algorithm MLi is configured to assign a predicted print quality indicator MLPki to at least one input digitized image 110. The machine learning algorithm MLi may be configured to automatically perform this step by performing a set of predefined rules.

[0304] One advantage is to automatically classify the digitized image 110 according to its print quality.

[0305] In one embodiment, the machin learning algorithm MLi comprise or is configured to implement a trained learning function.

[0306] In one embodiment, the machine learning algorithm MLi is trained using a training dataset comprising a plurality of labeled data.

[0307] The set of predefined rules may be determined based on a training of said machine learning algorithm MLi using the training dataset.

[0308] The training dataset may comprise a plurality of training digitized image 110”. The training dataset may also comprise a plurality of training print quality scores Sa” and / or a plurality of training print quality metrics Pmi”. Each training print quality score Sa” and each training print quality metrics Pmi may be associated with one single training digitized image 110”. The plurality of training digitized image 110” may be labelled according to an expected human rating of the print quality of the training digitized image 110”. One advantage is to train the machine learning algorithm to learn how the print quality scores and metrics can be weighted and combined to predict a correct subjective rating corresponding to an expected human rating.

[0309] In one embodiment, the method comprises a step of calculating a plurality of training print quality scores Sci” and / or a plurality of training print quality metrics Pm i” for each training printed element 25”.

[0310] The method may comprise a step of receiving a training digitized image 110” of a training printed element 25”.

[0311] The method may comprise a step of isolating at least one training region of interest in the training digitized image 110”.

[0312] The method may comprise a step of extracting at least one training value of interest Vai” associated with an isolated training region of interest.

[0313] The method may comprise a step of calculating a plurality of training print quality scores Sci” and / or a plurality of training print quality metrics Pmi” a plurality of training print quality indicators Pki” by performing a set of predefined rules.

[0314] The set of predefined rules may comprise calculating at least one print quality metric Pmi” using at least one training value of interest Vai’ and using at least one training value of reference Vri” calculated using a training reference image 210”.

[0315] The method 100 may comprise calculating at least one training print quality score Sa” using at least one training value of interest Vai”.

[0316] The machine learning algorithm MLi may comprise a supervised method or an unsupervised method.

[0317] The machine learning algorithm MLi may comprise using a neural network such as a convolutional neural network or a recurrent neural network. The neural network may comprise several layers among the following: convolutional layers, pooling layers, dropout layers, fully connected layers also known as dense layers, SoftMax layers, output layers.

[0318] The machine learning algorithm MLi may also comprise a model based on a random forest method.

[0319] The machine learning algorithm MLi may also comprise a deep learning method.

[0320] Working parameters The method 100 may comprise a step of receiving current working parameters Zini of the printing apparatus 1.

[0321] In one embodiment, the current working parameters Zini comprise a parameter relative to at least one element configured to contribute to supporting or transporting an ink support device 5, such as an endless ribbon 5 of the printing apparatus 1 .

[0322] An example of such parameter comprises a speed of at least one roller of the printing apparatus 1 , or a parameter of a motor driving said roller.

[0323] In one embodiment, the current working parameters Zini comprise a parameter relative to a coating composition coated on the surface of the ink support device 5 5. An example of such parameter comprises a thickness of the coating composition or the melting temperature of the coating composition.

[0324] In one embodiment, the current working parameters Zini comprise a parameter relative to a cooling device of the printing apparatus 1 .

[0325] An example of such parameter comprises a target temperature of a cooling device, for example a fan arranged to cool down a coated layer between a coating module of the printing apparatus 1 and a printing zone of the printing apparatus 1 .

[0326] The method 100 comprises a step of generating GENi adjusted working parameters Zadj of the coating module 7 of the printing apparatus 1.

[0327] The adjusted working parameters Zadj are generated using at least one print quality score Sci and / or at least one print quality metric Pm i.

[0328] The adjusted working parameters Zadj may be generated using the current working parameters Zini of the coating module 7 of the printing apparatus 1. For example, the method 100 may comprise a step of applying an algorithm receiving input data comprising at least one print quality score Sci and / or at least one print quality metric Pm i and the current working parameters Zini. The algorithm may be configured to perform a set of predefined rules to generate the adjusted working parameters Zadj of the coating module 7 of the printing apparatus 1 using the input data.

[0329] The adjusted working parameters Zadj may comprise at least one parameter among the following: a parameter relative to at least one element configured to contribute to supporting or transporting an endless ribbon 5 of the printing apparatus 1 , such as a speed of at least one roller of a conveyor system, a parameter relative to a coating composition coated on the surface of the ink support device 5, a parameter relative to a cooling device of the printing apparatus 1 , such as a target temperature value.

[0330] In one embodiment, the adjusted working parameters Zad comprises a speed parameter, such as an adjusted speed of the ink support device 5.

[0331] In one embodiment, the adjusted working parameters Zadj comprises a temperature parameter, such as an adjusted temperature of an ink layer applied to the ink support device 5.

[0332] In one embodiment, the adjusted working parameters Zad comprises an adjusted ink level in the reservoir.

[0333] In one embodiment, the adjusted working parameters Zad comprises a pressure parameter, such as a pressure applied by a squeeze roller onto the ink support device 5 and / or a speed parameter, such as a parameter related to the speed of ink support device 5.

[0334] In one embodiment, the adjusted working parameters Zadj are generated in real time.

[0335] More generally, the initial working parameters Zini and the adjusted working parameters Zadj can comprise any parameter characterizing the setup of an element of the coating module 7 of the printing apparatus 1 which may affect a printing quality of the printed element 25.

[0336] Optionally, the method 100 comprises a step of automatically generating a command signal Cmd using the generated adjusted working parameters Zadj. The command signal Cmd may be generated in real time using a calculator and transmitted in real time using a communication interface.

[0337] Optionally, the command signal Cmd is transmitted to the printing apparatus 1 by means of a communication interface.

[0338] In one embodiment, the command signal Cmd comprises a command for adjusting at least one parameter of the coating module 7. The command signal Cmd may be sent to at least one controller of the printing apparatus 1 , for example a controller of the coating module 7 to automatically adjust at least one working parameter Zadj of said coating module 7.

[0339] For example, the command signal Cmd may comprise a command sent to at least one controller for adjusting in real time at least one parameter of the coating module 7, such as an ink parameter, a speed parameter, a temperature parameter or a pressure parameter. System

[0340] According to another aspect, the invention relates to a system 1000 comprising at least one calculator 112 and at least one communication interface 111 configured to execute the steps of the method to the first aspect of the invention.

[0341] In one embodiment, the system 1000 comprises the printing apparatus 1 .

[0342] In one embodiment, the system 1000 comprises at least one optical detection device 26 and is configured to execute the step of the method for automatically adjusting the initial working parameters Zini of the printing apparatus 1 .

[0343] A non-restrictive example of a printing apparatus 1 of the system 1000 is described from page 9 ligne.1 to page 25 1.3 of patent application for which the international publication number is WO2022 / 12895. The description from page 9 ligne.1 to page 25 1.3 of said patent application is incorporated hereby by reference in the present detailed description.

[0344] According to another aspect, the invention relates to a printing apparatus 1 comprising an ink support device 5, a coating module 7 and an ink rejuvenation device, and comprising at least one calculator configured to execute the steps of the method for automatically generating GEN1 adjusted working parameters Zadj. The calculator may be configured to execute any of the steps of the method according to any embodiment or combination of embodiments of said method.

[0345] In one embodiment, the printing apparatus 1 comprises at least one controller. The controller may be configured to control at least one component of the coating module 7 according to the generated adjusted working parameters Zadj. The controller may comprise, but not limited to, a pressure controller, a temperature controller, a speed controller.

[0346] The controller may be configured to automatically adjust the working parameters Zadj of the coating module 7 of the printing apparatus 1 in real time, such as ink thickness, ink viscosity, ink composition, ink temperature, speed of the endless ribbon 5, pressure applied by the squeeze roller, temperature of the printhead, or any other relevant parameter of the coating module 7 allowing to improve printing quality. For that purpose, the controller may be configured to automatically control at least one control device of the coating module 7, such as a motor, for example a motor driving a roller, a heater, a cooler, such as a fan or a chill roller, a squeeze roller, etc.

[0347] According to another aspect, the invention relates to a computer program product comprising instructions to cause the system to execute the steps of the method according to the first aspect of the invention.

[0348] According to another aspect, the invention relates to a computer readable medium MEM having stored thereon the computer program.

[0349] Hardware configuration

[0350] Figure 7 illustrates an example of hardware configuration of the system 1000 of the invention.

[0351] The system 1000 can be seen as a calculator interacting with a computer program.

[0352] The system 1000 comprises a calculator 112. The calculator 112 comprises, for example, one or several processors adapted to interpret instructions in the form of computer programs. The processing may be executed by one processor sequentially or simultaneously, or according to another method, by one or several processors.

[0353] The calculator 112 may comprise a data processing module to perform calculations, a memory 212 connected to the data processing module, a computer readable medium and optionally a reader adapted to read the computer readable medium.

[0354] The system 1000 may comprise an input module, an output module, and a communication interface 111.

[0355] Each function of the system 1000 may be executed by making the data processing module to read a predetermined program on a material such as the memory 212, so that the data processing module executes calculations, commands communications to the communication interface and commands reading or writing data in the memory 212 and in the computer readable medium.

[0356] The method may be executed on one computer or on a distributed system between several computers (for example cloud computing).

[0357] The memory 212 is a computer readable storing medium and may be configured with, for example, a random-access memory or any other storage medium that would be adequate. The memory 212 may comprise an operating system to load the program of the invention. The memory 212 may comprise means for storing parameters variables created and modified during the execution of the precited program.

[0358] The instructions of the program may be stored on a computer readable storing support comprising, for example, a removable support, such as for example, and not limited to, a compact disc read only memory, a removable disc, a database, a server, or any other adapted storage support.

[0359] The instructions of the program may also come from an external source and be downloaded through a network. In that case, the program may comprise a computer readable data support on which are stored the instructions of the program or a data support on which are encoded the instructions of the program.

[0360] The system 1000 may comprise a user interface 220 comprising an input device and an output device.

[0361] The input device comprises for example a keyboard and a pointing interface such as a mouse.

[0362] The output device is adapted to return information to a user, electrically or sensory, for example visually or sonorously. The output device comprises for example a graphical user interface. The output interface may comprise the input device, for example in the case of a tablet.

[0363] The set of at least one communication interface allows communication between elements of the system 1000 and optionally between at least one element of the system 1000 and one element external to the system 1000. The set of at least one communication interface may establish a physical link or a wireless link between elements of the system 1000 and / or between at least one element of the system 1000 and at least one device external to the system 1000.

Claims

CLAIMS1. A computer implemented method (100) for automatically generating (GENi) working parameters of a printing apparatus (1 ) comprising a coating module (7), an ink support device (5) and an ink rejuvenation device, the method (100) comprising:• Receiving at least one print quality score (Sci) and / or at least one print quality metric (Pmi), said print quality score (Sci) and said print quality metric (Pmi) characterizing a print quality of a printed element (25) printed by means of the printing apparatus (1 );• Automatically generating (GENi) adjusted working parameters (Zadj) of the coating module (7) using said at least one print quality score (Pmi) and / or using said at least one print quality metric (Pmi).

2. The method (100) according to claim 1 , wherein the printing apparatus (1 ) comprises at least one controller configured to control at least one component of the coating module (7), and wherein the method (100) further comprises a step of automatically adjusting at least one working parameter (Zadj) by means of said controller.

3. The method (100) according to claim 1 to 2, wherein at least one generated adjusted working parameter (Zadj) comprises the thickness of an ink layer applied onto the ink support device (5).

4. The method according to any of claims 1 to 3, wherein at least one generated adjusted working parameter (Zadj) comprises a speed of the ink support device (5).

5. The method (100) according to any of claims 1 to 4, wherein the printing apparatus (1 ) further comprises at least one support element to support the ink support device (5) on an inner face of said ink support device (5).

6. The method (100) according to any of claims 1 to 5, wherein the coating module (7) comprises a squeeze ink roller and an active element to press said squeeze ink roller onto an outer face of the ink support device (5), and wherein the adjusted parameter of the coating module (7) comprise at least one pressure parameter related to a pressure applied by said active element to said squeeze ink roller.

7. The method (100) according to any of claims 1 to 6, wherein at least one print quality score (Sa) and / or at least one print quality metric (Pm i) is generated using a human machine interface.

8. The method (100) according to any of claim 1 to 7, wherein at least one print quality score (Sa) and / or at least one print quality metric (Pmi) is calculated by processing a digitized image (110) of the printed element (25).

9. The method (100) according to claim 8, wherein at least one print quality metric (Pmi) is calculated by processing the digitized image (110) of the printed element (25) and by processing a reference image (210) of a printed element (25).

10. The method (100) according to any of claims 1 to 9, further comprising:• Receiving (RECi) a digitized image (110) of at least one printed element (25) by means of a first communication interface (111 ), said digitized image (110) comprising a plurality of digitized patterns (Dpi, .... Dpn) distributed in a plurality of regions of interest (Rii , Rin) ;• Performing the following steps by means of at least one calculator (112):■ Extracting (EXT 1 ) at least one first value of interest (Van ) from at least one region of interest among the plurality of regions of interest (Rii , Rin);■ Calculating at least one print quality score (Sei) and / or calculating at least one print quality metric (Pmi) by respectively:- Extracting (EXT2) at least one second value of interest (Vai2) distinct of the first value of interest (Vaii) and calculating (CLC1) said print quality score (Sa) using the first value of interest (Van) and using the second value of interest (Vai2) and / or;- Calculating (CLC2) said print quality metric (Pmi) using the first value of interest (Van) and using at least one value of reference (Vn);11. The method (100) according to claim 10, comprising:• Receiving (REC2) a reference image (210) comprising a plurality of reference patterns (Dprefi , .... Dprefn) distributed in a plurality of reference regions of interest (Rirefi , ... , Rirefn);• Extracting (EXT3) the value of reference (Vn) from at least one of said plurality of reference regions of interest (Rirefi , .... Rirefn);• Calculating (CLC2) at least one print quality metric (Pmi) using the first value of interest (Van) and using the extracted value of reference (Vn), wherein the adjusted working parameters (Zadj) are automatically generated using said calculated print quality metric (Pmi).

12. The method (100) according to any of claims 10 to 11 , comprising a step of extracting a plurality of values of reference (Vn, .... Vrn) from the plurality of regions of interest (Rirefi , ... , Rirefn) to calculate a plurality of print quality metrics (Pmi), and wherein the adjusted working parameters (Zadj) are generated using said calculated plurality of print quality metrics (Pmi , ... , Pmi).

13. The method (100) according to any of claims 10 to 12, wherein the first value of interest (Vaii) and the second value of interest (Vai2) are extracted from a same region of interest of the plurality of regions of interest (Rii , ..., Rin).

14. The method (100) according to any of claims 10 to 13, comprising extracting a plurality of values of interest (Vai , ... , Vai) from at least two distinct regions of interest of the plurality of regions of interest (Rii , , Rin), and wherein the adjusted working parameters (Zadj) are generated using said plurality of values of interest (Vai, ... , Vai).

15. The method according to any of claims 10 to 14, comprising automatically generating at least one predicted print quality score (MSa) and / or at least one predicted print quality metric (MPrrii) by means of a machine learning algorithm (MLi) using at least one digitized image (110) as input data of said machine learning algorithm (MLi).

16. The method (100) according to claim 15, wherein the plurality of training digitized images (110”) used to train the machine learning algorithm (MLi) are labelled according to an expected human rating of their print quality.

17. A system (1000) comprising at least one calculator (112) and at least one communication interface (111 ), said system (1000) comprising hardware means and / or software means to execute the steps of the computer implemented method (100) according to any of claims 1 to 16.

18. The system (1000) according to claim 17, further comprising at least one optical detection device (26) to detect a printed element (25).

19. Printing apparatus (1 ) comprising a coating module (7), an ink support device (5) and an ink rejuvenation device, and comprising a calculator configured to execute any of the steps of the method according to any of claims 1 to 16.

20. Printing apparatus (1 ) according to claim 19, further comprising at least one support element to support the ink support device (5) on an inner face of said ink support device (5).

21. Printing apparatus (1 ) according to claim 20, wherein the coating module (7) further comprises a squeeze ink roller and an active element to press said squeeze ink roller onto an outer face of the ink support device (5).

22. A computer program product comprising instructions to cause the system (1000) according to claims 17 to 18 to execute the steps of the method according to any of claims 1 to 16.

23. A computer-readable medium having stored thereon the computer program of claim 22.

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