Method for creating a digitally printed décor comprising a concealed code

Abstract

Method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a sheet. The decorative pattern is modified such that it comprises a concealed code. The method comprises the steps of - printing a first master decor showing the decorative pattern on a first sample of the sheet, thereby obtaining a first sample sheet comprising the first master decor; - performing a process on the first sample sheet comprising the first master decor, wherein the process causes a deformation of the printed first master decor on this first sample sheet; - measuring this deformation on the first sample sheet; - modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process; - generating a control file for a digital printer for printing the second master decor on a sheet having the same characteristics as the first sample sheet; characterized in that the printed second master decor comprises the concealed code invisible to the human eye but machine readable.

Description

[0001] Method for creating a digitally printed decor comprising a concealed code

[0002] The invention relates to a method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a sheet or board, wherein the decorative pattern is modified such that it comprises a concealed code. A sheet printed with the decorative pattern comprising the concealed code can be used for the decor layer for a decorative panel, e.g. a floor panel. The concealed code is invisible to the human eye, but is machine readable.

[0003] WO2019 / 072733A1 discloses an inkjet printing method for manufacturing decorative laminate panels ordered by a customer. The method includes the steps of: i) providing an inkjet printing device with a print job including one or more decorative patterns and an identification code assigned to the one or more decorative patterns; and ii) printing the one or more decorative patterns with one or more inkjet inks and applying the identification code on a substrate web. The substrate web is a paper substrate. The one or more inkjet inks are aqueous pigmented inkjet inks are printed on the substrate web before impregnation with a thermosetting resin; or the one or more inkjet inks are UV curable inkjet inks and the substrate web is a thermoplastic substrate web based on a material selected from the group consisting of polyvinylchloride (PVC), polypropylene (PP), polyethylene (PE), polyethylene-terephthalate (PET) and thermoplastic polyurethane (TPU). The identification code can be concealed in the one or more decorative patterns with steganographic techniques.

[0004] It is known to provide panels which have a printed decor and an embossed texture in register with the printed decor. The combination of the printed decor and the embossed texture provide the decorative aspect of the panel. Such panels are known that simulate a wood panel.

[0005] W02023 / 007306A1 discloses a method for manufacturing a printed decor sheet. The method comprises the steps of: providing a first printable or printed sheet of paper; performing at least one predetermined operation on the sheet of paper, wherein the predetermined operation causes the deformation of the sheet of paper in at least one direction; measuring the deformation to obtain at least one deformation parameter; providing a first master image; performing an image processing operation on the first master image to obtain a second master image; and printing the second master image on a second sheet of paper to obtain the decor sheet. The image processing operation involves at least modifying the first master image on the basis of the first deformation parameter.

[0006] W02023 / 007307A1 discloses a method for manufacturing a printed decor sheet. The method comprises the steps of: providing a first printable or printed thermoplastic layer; performing at least one predetermined operation on the substrate, wherein the predetermined operation causes the deformation of the printed thermoplastic layer in at least one direction; measuring the deformation to obtain at least one deformation parameter; providing a first master image; performing an image processing operation on the first master image to obtain a second master image; and printing the second master image on a second printable thermoplastic layer to obtain the decor sheet. The image processing operation involves at least modifying the first master image on the basis of the first deformation parameter.

[0007] It is a challenge to ensure that a concealed code does not disturb the visual aspect of the printed decorative pattern. It is a further challenge to add the concealed code to the decorative pattern to be printed in such a way that it can be read afterwards without problems.

[0008] The first aspect of the invention is a method for generating a control file for a digital printer. The control file is provided for printing a decorative pattern on a sheet. The decorative pattern is modified such that it comprises a concealed code. The method comprises the steps of

[0009] - printing a first master decor showing the decorative pattern on a first sample of the sheet, thereby obtaining a first sample sheet comprising the first master decor; - performing a process on the first sample sheet comprising the first master decor, wherein the process causes a deformation of the printed first master decor on this first sample sheet;

[0010] - measuring this deformation on the first sample sheet;

[0011] - modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process;

[0012] - generating a control file for a digital printer for printing the second master decor on a sheet having the same characteristics as the first sample sheet.

[0013] The printed second master decor comprises the concealed code invisible to the human eye but machine readable.

[0014] The second aspect of the invention relates to a method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a sheet, wherein the decorative pattern is modified such that it comprises a concealed code. The method comprises the steps of

[0015] - providing a printed or printable first sample of the sheet, thereby obtaining a first sample sheet;

[0016] - performing a process on the first sample sheet, wherein the process causes a deformation on this first sample sheet;

[0017] - measuring this deformation on the first sample sheet;

[0018] - providing a first master decor comprising the decorative pattern;

[0019] - modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process;

[0020] - generating a control file for a digital printer for printing the second master decor on a sheet having the same characteristics as the first sample sheet.

[0021] The printed second master decor comprises the concealed code invisible to the human eye but machine readable.

[0022] The method of the second aspect of the invention comprises the step of providing a printed or printable first sample of the sheet. An example of a printable first sample of the sheet that can be used in the invention is a sheet of paper comprising a primer that makes the sheet of paper suitable for digital printing.

[0023] The first sample sheet can be a printed first sample of the sheet. This first sample sheet can e.g. be printed with marks that allow easy detection of the deformation of the first sample sheet occurring in the process the first sample sheet undergoes. Such marks can e.g. include straight lines or straight line segments on predetermined distance from each other.

[0024] The third aspect of the invention is a method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a sheet, wherein the decorative pattern is modified such that it comprises a concealed code. The method comprises the steps of

[0025] - providing a first master decor comprising the decorative pattern;

[0026] - modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for expected deformation occurring in processes the sheet undergoes after being printed with the decorative pattern;

[0027] - generating a control file for a digital printer for printing the second master decor on a sheet having the same characteristics as the first sample sheet.

[0028] The printed second master decor comprises the concealed code invisible to the human eye but machine readable

[0029] In the third aspect of the invention, for the compensation of expected deformations occurring in process the sheet will undergo after being printed with the decorative pattern use can be made of data previously generated from experiments, or use can be made of data from suppliers of such sheets. Data previously generated can be derived from printable or printed sheets that underwent the same or similar processes the sheet printed with the decorative pattern comprising the concealed code will undergo after being printed. Such process can include impregnation with a thermosetting resin (e.g. a melamine formaldehyde resin) when the sheet is a sheet of paper for use as decor layer in a laminated floor panel having a wood fiber board as substrate and the sheet of paper printed with the decorative pattern as decor layer.

[0030] It is a benefit of the first aspect of the invention, of the second aspect of the invention and of the third aspect of the invention that it is ensured that the code is invisible to the human eye and machine readable in an excellent way. Reading the code with an app on a smartphone allows to access information linked to the concealed code.

[0031] Products such as floor panels or wall panels only have their decorative side visible after installation. It is therefore a challenge to provide information on the products to persons wanting to have information such information during the lifetime of the products, when the panels are installed. Providing a concealed code in the decorative pattern allows to communicate useful information om the products, after reading the concealed code with appropriate technical means (e.g. using an app on a smartphone in which the camera of the smart phone is used). Such information can e.g. relate to installation instructions, maintenance instructions (e.g. cleaning instructions), product manufacturer, product authentication, anti-counterfeit information, product composition or product recycling instructions.

[0032] A preferred embodiment of the method of the first aspect of the invention and / or of the method of the second aspect of the invention and / or of the third aspect of the invention is characterized in that the concealed code is added to the decorative pattern before the step of modifying the first master decor thereby obtaining the second master decor.

[0033] Such embodiments have the benefit that the code is added to the decorative patterns early on in the process from design of the decorative pattern to control file for the digital printing. This eliminates extra steps when the decorative pattern is used for printing on different digital printers, or on different types of sheets or on sheets that undergo differing processes after printing. The concealed code can be checked early on and in the different process steps leading up to the generation of the control code to verify whether or not the code is well concealed and whether or not the code can be read efficiently and effectively via technical means. A preferred embodiment of the method of the first aspect of the invention and / or of the second aspect of the invention and / or of the third aspect of the invention is characterized in that the method comprises the step of banding compensation before the step of modifying the first master decor thereby obtaining the second master decor. The step of banding compensation comprises the step of modifying the first master decor to compensate for variable density output of the individual printheads of the digital printer to be used for printing the decorative pattern on the sheet. The concealed code is added to the decorative pattern before the step of banding compensation.

[0034] Inkjet printheads can produce variable density output across an individual printhead and between inkjets. Printheads can also wear over time, this wear can be different for the different printheads. Therefore, banding compensation allows to correct for differences between inkjet printheads - e.g. between the different printheads positioned over the width of the digital printing - and for wear occurring in the printheads. Banding compensation is a way to ensure that the printed decorative pattern corresponds with the intended decorative pattern.

[0035] Such embodiments ensure that the banding compensation is also applied to the concealed code, ensuring that the intended concealed code is printed. Such embodiments fully ensure that the code is well concealed and very well machine readable.

[0036] A preferred embodiment of the method of the first aspect of the invention and / or of the second aspect of the invention and / or of the third aspect of the invention is characterized in that the method comprises the step of banding compensation before the step of modifying the first master decor thereby obtaining the second master decor. The step of banding compensation comprises the step of modifying the first master decor to compensate for variable density output of the individual printheads of the digital printer to be used for printing the decorative pattern on the sheet. The concealed code is added to the decorative pattern after the step of banding compensation. Such embodiments have the benefit that in the final printed decor a better readable code is obtained, as the code is added after the banding compensation such that it is not modified in banding, which could reduce the readability of the code in the final printed decor. Furthermore, the code is added after the color pattern for the decorative pattern is final, such that the code can be generated for optimal concealing of it and for optimal machine readability.

[0037] A preferred embodiment of the method of the first aspect of the invention and / or of the second aspect of the invention and / or of the third aspect of the invention is characterized in that the concealed code is added to the decorative pattern after the step of modifying the first master decor thereby obtaining the second master decor.

[0038] Such embodiments have the benefit that a better readable code is obtained in the final product printed with the decorative pattern. There is no risk that the code geography (e.g. a code geography composed of a number of squares) is modified in the process that the printed sheet will undergo, as the code is added after obtaining the second mater decor which compensates for deformations in processes the printed sheet will undergo.

[0039] In a preferred embodiment, the concealed code is added to the decorative pattern after the step of modifying the first master decor thereby obtaining the second master decor. The concealed code is added to the decorative pattern before the step of generating the control file for a digital printer for printing the second master decor on a sheet having the same characteristics as the first sample sheet.

[0040] It is a benefit of such embodiments that the code is added to a decor file which can be easily checked for its outcome once printed.

[0041] In a preferred embodiment of the first aspect of the invention and / or of the second aspect of the invention and / or of the third aspect of the invention, the concealed code is added to the decorative pattern after the step of modifying the first master decor thereby obtaining the second master decor; wherein the method comprises the step of incorporating the concealed code into the control file after a control file has been generated from the second master decor.

[0042] This embodiment allows adding the code in such way that only a limited number of the spot colors used in digital printing are used to print the code, and / or that specific spot colors are not used to print the code. It is a benefit that - e.g. with taking the nature of the decorative pattern into account - problems with unwanted shade changes or metamerism can be prevented. It is e.g. beneficial for wood decors printed in a CMYK (cyan - magenta - yellow - key) or CRYK (cyan - red - yellow - key) inkjet ink set system that cyan is not modified for generating the code, as cyan is not used much in printing the wood decor, changes of it could lead to a greenish appearance of the final printed decorative wood pattern.

[0043] A preferred embodiment of the method of the first aspect of the invention and / or of the second aspect of the invention and / or of the third aspect of the invention is characterized in that the process comprises one or a plurality of process steps which the printed sheet will undergo for use as decorative layer of a decorative panel. More preferably, wherein the decorative layer of the decorative panel comprises a surface texture, more preferably a surface texture in register with the decorative pattern of the decorative layer.

[0044] It means that - in such embodiments according to the first aspect of the invention - the process performed on the first sample sheet comprising the first master decor, process causing a deformation of the printed first master decor on this first sample sheet, comprises one or a plurality of process steps which the printed sheet will undergo for use as decorative layer of a decorative panel.

[0045] It means that - in such embodiments according to the second aspect of the invention - the process performed on the first sample sheet - process which would cause a deformation of the first master decor if it would have been printed on this first sample sheet - comprises one or a plurality of process steps which the printed sheet will undergo for use as decorative layer of a decorative panel. Such embodiments have the benefit that the process simulates very well the process the sheet printed with the decorative pattern will undergo when further processing it, e.g. as a decorative layer for a decorative panel. It means e.g. that the deformation is compensated such that an embossing in register with the designed decorative pattern will be performed correctly on the sheet printed with the decorative pattern comprising the concealed code.

[0046] A preferred embodiment of the method of the first aspect of the invention and / or of the second aspect of the invention and / or of the third aspect of the invention is characterized in that the sheet is a sheet of paper.

[0047] The process - according to the first aspect of the invention and / or of the second aspect of the invention and / or of the third aspect of the invention - can comprise the impregnation (and preferably also the drying after the impregnation) of the sheet of paper with a resin, preferably with a thermosetting resin, e.g. a melamine formaldehyde resin or an acrylic resin. As a consequence of this process, the deformation of the sheet of paper can comprise or consist of an elongation of the sheet of paper.

[0048] W02023 / 007306A1 - incorporated by reference - describes a preferred process a sheet of paper onto which a decorative pattern has been digitally printed can undergo for use as decor layer in a decorative panel. Reference is made to figure 3 - and the corresponding part of the description - describing the process steps, including impregnation with a thermosetting resin followed by drying of the impregnated sheet of paper. Figure 4 of W02023 / 007306A1 provides a description of process steps in the digital printing of a decorative pattern onto a sheet of paper using an inkjet printer.

[0049] A preferred embodiment of the method of the first aspect of the invention and / or of the second aspect of the invention and / or of the third aspect of the invention is characterized in that the sheet is a thermoplastic foil, e.g. a polyvinylchloride (PVC) foil, a polyethylene (PE) foil, a polypropylene (PP) foil, or a polyester foil.

[0050] The foil can preferably have a thickness ranging between 40 micron and 200 micron. The process - according to the first aspect of the invention or of the second aspect of the invention and / or of the third aspect of the invention - can comprise the lamination - preferably the thermal lamination - of the thermoplastic foil onto a board, preferably onto a synthetic board (e.g. a PVC based board) or onto a mineral board.

[0051] The process - according to the first aspect of the invention or of the second aspect of the invention and / or of the third aspect of the invention - can comprise the lamination - preferably the thermal lamination - of a transparent thermoplastic foil on the printed thermoplastic foil. The transparent thermoplastic foil can be laminated onto the side of the printed thermoplastic foil that has been printed. The transparent thermoplastic foil can provide a wear layer on a decorative panel - e.g. a floor panel - comprising the printed thermoplastic foil as decorative layer.

[0052] W02023 / 007306A1 - incorporated by reference - describes a preferred process a thermoplastic foil onto which a decorative pattern has been digitally printed can undergo for use as decor layer in a decorative panel. Figures 3 and 6 illustrate process steps a thermoplastic foil can undergo for use as decorative layer for a decorative panel. Figure 4 of W02023 / 007306A1 provides a description of process steps in the digital printing using an inkjet printer of a decorative pattern onto a thermoplastic foil, e.g. a polyvinyl chloride foil.

[0053] The fourth aspect of the invention is a method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a board, wherein the decorative pattern is modified such that it comprises a concealed code. The method comprises the steps of

[0054] - printing a first master decor showing the decorative pattern on a first sample of the board, thereby obtaining a first sample board comprising the first master decor;

[0055] - performing a process on the first sample board comprising the first master decor, wherein the process causes a deformation of the printed first master decor on this first sample board;

[0056] - measuring this deformation on the first sample board; - modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in the process;

[0057] - generating a control file for a digital printer for printing the second master decor on a board having the same characteristics as the first sample board; characterized in that the printed second mater decor comprises the concealed code invisible to the human eye but machine readable.

[0058] The fifth aspect of the invention is a method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a board, wherein the decorative pattern is modified such that it comprises a concealed code; wherein the method comprises the steps of

[0059] - providing a printed or printable first sample of the board, thereby obtaining a first sample board;

[0060] - performing a process on the first sample board, wherein the process causes a deformation of first sample board;

[0061] - measuring this deformation on the first sample board;

[0062] - - providing a first master decor comprising the decorative pattern;

[0063] - modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process;

[0064] - generating a control file for a digital printer for printing the second master decor on a board having the same characteristics as the first sample board; characterized in that the printed second mater decor comprises the concealed code invisible to the human eye but machine readable.

[0065] The method of the fifth aspect of the invention comprises the step of providing a printed or printable first sample of the board.

[0066] An example of a printable first sample of the board that can be used in the invention is an unfired ceramic board prepared for being printed via digital printing.

[0067] The first sample board can be a printed first sample of the board. This first sample board can e.g. be printed with marks that allow easy detection of the deformation of the first sample board occurring in the process the first sample board undergoes. Such marks can e.g. include straight lines or straight line segments on predetermined distance from each other.

[0068] The sixth aspect of the invention is a method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a board, wherein the decorative pattern is modified such that it comprises a concealed code; wherein the method comprises the steps of

[0069] - providing a first master decor comprising the decorative pattern;

[0070] - modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for expected deformation occurring in processes the sheet undergoes after being printed with the decorative pattern;

[0071] - generating a control file for a digital printer for printing the second master decor on a board.

[0072] The printed second mater decor comprises the concealed code invisible to the human eye but machine readable.

[0073] In the sixth aspect of the invention, for the compensation of expected deformations occurring in process the board will undergo after being printed with the decorative pattern use can be made of data previously generated from experiments, or use can be made of data from suppliers of such boards or of material for making such boards. Data previously generated can be derived from printable or printed board that underwent the same or similar processes the board printed with the decorative pattern comprising the concealed code will undergo after being printed. Such process can include baking the printed board in a kiln thereby obtaining a decorated ceramic tile.

[0074] It is a benefit of the fourth aspect of the invention and of the fifth aspect of the invention and of the sixth aspect of the invention that it is ensured that the code is invisible to the human eye and machine readable in an excellent way. Reading the code with an app on a smartphone allows to access information linked to the concealed code. Products such as floor tiles or wall tiles only have their decorative side visible after installation. It is therefore a challenge to provide information on the products to persons wanting to have information such information during the lifetime of the products, when the tiles are installed. Providing a concealed code in the decorative pattern allows to communicate useful information om the products, after reading the concealed code with appropriate technical means (e.g. using an app on a smartphone in which the camera of the smart phone is used). Such information can e.g. relate to maintenance instructions (e.g. cleaning instructions), product manufacturer, product authentication, product composition or product recycling instructions.

[0075] Boards can shrink or deform otherwise during the baking or curing process after digital printing. The methods of the fourth aspect of the invention and of the fifth aspect of the invention and of the sixth aspect of the invention allow to ensure that the decorative pattern and the concealed code are effectively printed as designed, as deformation in the baking or curing process is compensated in the method.

[0076] A preferred embodiment of the fourth aspect of the invention and / or of the fifth aspect of the invention and / or of the sixth aspect of the invention is characterized in that the board is a ceramic board, a quartz board or an engineered stone board before or after the board is baked or cured.

[0077] Ceramic board, quartz boards or engineered stone boards can be printed before baking or curing the board itself. The boards can shrink or deform in the baking or printing process. The methods of the fourth aspect of the invention and of the fifth aspect of the invention and of the sixth aspect of the invention allow to ensure that the decorative pattern and the concealed code are effectively printed as designed, as deformation in the baking or curing process is compensated.

[0078] A preferred quartz board and / or a preferred engineered stone board for use in the fourth aspect and / or in the fifth aspect of the invention and / or of the sixth aspect of the invention comprises a mixture of mineral fillers (e.g. comprising SiCh-based minerals) in a content of 85-90 %wt and a thermosetting binder in a content of 10-15 %wt. The thermosetting binder can preferably be an unsaturated polyester binder.

[0079] A preferred embodiment of the fourth aspect of the invention and / or of the fifth aspect of the invention and / or of the sixth aspect of the invention is characterized in that the concealed code is added to the decorative pattern before the step of modifying the first master decor thereby obtaining the second master decor.

[0080] Such embodiments have the benefit that the code is added to the decorative patterns early on in the process. This eliminates extra steps when the decorative pattern in used for printing on different digital printers, or on different types of boards or on boards that undergo differing processes after printing. The concealed code can be checked early on and in the different process steps leading up to the generation of the control code if the code is well concealed and if the code can be read efficiently and effectively.

[0081] A preferred embodiment of the fourth aspect of the invention and / or of the fifth aspect of the invention and / or of the sixth aspect of the invention is characterized in that the method comprises the step of banding compensation before the step of modifying the first master decor thereby obtaining the second master decor. The step of banding compensation comprises the step of modifying the first master decor to compensate for variable density output of the individual printheads of the digital printer to be used for printing the decorative pattern on the sheet. The concealed code is added to the decorative pattern before the step of banding compensation.

[0082] Inkjet printheads can produce variable density output across an individual printhead and between inkjets. Printheads can also wear over time, this wear can be different for the different printheads. Therefore, banding compensation allows to correct for differences between inkjet printheads - e.g. between the different printheads positioned over the width of the digital printing - and for wear occurring in the printheads. Banding compensation is a way to ensure that the printed decorative pattern corresponds with the intended decorative pattern. Such embodiments ensure that the banding compensation is also applied to the concealed code, ensuring that the intended concealed code is printed. Such embodiments fully ensure that the code is well concealed and very well machine readable.

[0083] A preferred embodiment of the fourth aspect of the invention and / or of the fifth aspect of the invention and / or of the sixth aspect of the invention is characterized in that the method comprises the step of banding compensation before the step of modifying the first master decor thereby obtaining the second master decor. The step of banding compensation comprises the step of modifying the first master decor to compensate for variable density output of the individual printheads of the digital printer to be used for printing the decorative pattern on the sheet. The concealed code is added to the decorative pattern after the step of banding compensation.

[0084] Such embodiments have the benefit that in the final printed decor a better readable code is obtained, as the code is added after the banding compensation such that it is not modified in banding, which could reduce the readability of the code in the final printed decor. Furthermore, the code is added after the color pattern for the decorative pattern is final, such that the code can be generated for optimal concealing of it and for optimal machine readability.

[0085] A preferred embodiment of the fourth aspect of the invention and / or of the fifth aspect of the invention and / or of the sixth aspect of the invention is characterized in that the concealed code is added to the decorative pattern after the step of modifying the first master decor thereby obtaining the second master decor.

[0086] Such embodiments have the benefit that a better readable code is obtained in the final product printed with the decorative pattern. There is no risk that the code geography (e.g. a code geography composed of a number of squares) is modified in the process that the printed sheet will undergo, as the code is added after obtaining the second mater decor which compensates for deformations in processes the printed sheet will undergo. More preferably, the concealed code is added to the decorative pattern before the step of generating a control file for a digital printer for printing the second master decor on a board having the same characteristics as the first sample board.

[0087] A preferred embodiment of the fourth aspect of the invention and / or of the fifth aspect of the invention and / or of the sixth aspect of the invention is characterized in that the method comprises the step of incorporating the concealed code into the control file after a control file has been generated from the second master decor.

[0088] This embodiment allows adding the concealed code in such a way that only a limited number of the spot colors used in digital printing are used to print the code, and / or that specific spot colors are not used to print the code. It is a benefit that - e.g. with taking the nature of the decorative pattern in to account - problems with unwanted shade changes or metamerism can be prevented. It is e.g. beneficial for wood decors printed in a CMYK (cyan - magenta - yellow - key) or CRYK (cyan - red - yellow - key) inkjet ink set system that cyan is not modified for generating the code, as cyan is not used much in printing the wood decor, changes of it could lead to a greenish appearance of the final printed decorative wood pattern.

[0089] A preferred embodiment of the fourth aspect of the invention and / or of the fifth aspect of the invention and / or of the sixth aspect of the invention is characterized in that the process comprises one or a plurality of process steps which the printed board will undergo in the process of producing a decorative panel or decorative tile from it.

[0090] Such embodiments have the benefit that the process the first sample board will undergo is a simulation of the process the printed board will undergo in the process of producing a decorative panel or decorative tile. This way, the deformation corresponds with the deformation in the real production process, and effective and efficient compensation for this deformation can be realized.

[0091] The process can e.g. comprise baking or curing of the first sample board onto which the first sample decor has been printed. The seventh aspect of the invention is a method - optionally a method as in any embodiment of the first aspect of the invention, or as in any embodiment of the second aspect of the invention, or as in any embodiment of the third aspect of the invention, or as in any embodiment of the fourth aspect of the invention, or as in any embodiment of the fifth aspect of the invention or as in any embodiment of the sixth aspect of the invention - for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a substrate, wherein the decorative pattern is modified such that it comprises a concealed code invisible to the human eye but machine readable.

[0092] It is a benefit of the invention that it is ensured that the code is invisible to the human eye and machine readable in an excellent way. Reading the code with an app on a smartphone allows to access information linked to the concealed code.

[0093] The substrate can e.g. be a sheet or a board, e.g. a mineral board optionally before baking or curing it.

[0094] A preferred embodiment of the seventh aspect of the invention is characterized in that a first control file is generated for printing the decorative pattern without concealed code, followed by the step of modification of the control file such that the decorative pattern to be printed comprises the concealed code.

[0095] Adding the concealed code at control file level has the benefit that the addition of the concealed code is done at the final stage of the whole design and preparation process for digital printing.

[0096] The decorative pattern can be a wood pattern. Wood patterns are frequently used in decorative panels, e.g. in floor panels.

[0097] A preferred embodiment of the seventh aspect of the invention is characterized in that the concealed code is continuously repeated over the full decorative pattern. Such embodiments have the benefit that the concealed code is still readable, even if part of the decorative pattern is obscured from view. Such is the case in floor coverings comprising floor panels when e.g. a rug is placed over part of the area covered by the floor panels.

[0098] A preferred embodiment of the seventh aspect of the invention is characterized in that the code is a steganographic code.

[0099] Steganographic codes are machine readable, but invisible to the human eye. Steganography is also known as invisible digital watermarking. In steganography, the concealed code is printed by the same one or plurality of inkjet inks used for inkjet printing of the decorative pattern. As no additional inkjet heads are required for printing the concealed code, printing the decorative pattern with the concealed code can be done at the same printing cost as printing without the concealed code.

[0100] A preferred embodiment is characterized in that the printed code is composed of a pattern of squares and or rectangles.

[0101] This way, easy readable concealed codes can be built, e.g. QR-type codes.

[0102] A preferred embodiment is characterized in that the printed code is composed of a series of clusters of pixels, wherein each pixel in a cluster of pixels has the same color. This way, easy readable concealed codes can be built.

[0103] A preferred embodiment is characterized in that the printed code comprises or is composed of missing dots in the decorative pattern.

[0104] Such embodiments have the benefit that less ink is consumed. Such embodiment is particularly beneficial when the decorative pattern represents a uni color, as unwanted color variation due to the presence of the concealed code is prevented. A preferred embodiment is characterized in that the control file provides instructions for a digital printer for printing with spot colors - e.g. with 4, 8 or 10 spot colors wherein the code is created by modification of less than 4 of the spot colors, preferably of less than 3 of the spot colors, and preferably of only 2 of the spot colors.

[0105] It is a benefit of such embodiments that the code can be more easily generated. It is a further benefit that the code can be generated using the spot colors most used in the decorative pattern. Using the spot colors least used in the decorative pattern could lead to unwanted visual deviations in the printed decorative pattern.

[0106] With “most used” and “least used” is preferably respectively meant that most and least volume of the ink of that spot color is consumed in printing the decorative pattern.

[0107] A preferred embodiment is characterized in that the decorative pattern and the concealed code are printed by means of digital printing using the same four color inkset, e.g. a CMYK inkjet ink set or a CRYK inkjet.

[0108] CMYK injet ink sets (C= cyan, M= magenta, Y= yellow, K= key, black) are well known in digital printing. CRYK inkjet ink sets are similar to CMYK injet ink sets in which the M (magenta) is replace by R (ref). CMYK injet ink sets are particularly beneficial for wood decors, because of it being better suited for printing the different shades in wood colors, including wood grain.

[0109] A preferred embodiment is characterized in that the concealed code is generated by modifying only one, only two or only three of the spot colors.

[0110] Such embodiment facilitates the generation of the concealed code. Furthermore, such embodiment allows avoiding the modification of a spot color not used much in the decorative pattern, which otherwise could change the visual aspect of the decorative pattern in an unwanted way. A preferred embodiment is characterized in that C (cyan) is less modified than at least Y and / or K when using the CMYK inkjet ink set or when using the CRYK inkjet ink set, for the generation of the concealed code.

[0111] Such embodiments are beneficial, for all types of decors but especially for wood decors, as modification of C (cyan) could result in unwanted metamerism of the printed decorative pattern. In addition, in wood decorative patterns, modification of C (cyan) could lead to an unwanted greenish hue.

[0112] With “C (cyan) is less modified than at least Y and / or K” is preferably meant that in less pixels of the decorative pattern the volume of C ink is modified compared to the amount of pixels in which the volume of Y ink and / or the volume of K ink is modified when incorporating the concealed code into the decorative pattern.

[0113] A preferred embodiment is characterized in that C (cyan) is not modified for the generation of the concealed code.

[0114] Such embodiments are beneficial, for all types of decors but especially for wood decors, as modification of C (cyan) could result in unwanted metamerism of the printed decorative pattern. In addition, in wood decorative patterns, modification of C (cyan) could lead to an unwanted greenish hue.

[0115] A preferred embodiment is characterized in that Y (yellow) and / or K (black) are most or exclusively modified for the generation of the concealed code.

[0116] It is beneficial to modify Y (yellow) for the generation of the concealed code as yellow is not well visible to the human eye. Modifications to yellow will thus be very well concealed for the human eye, but are well visible to cameras used to read the concealed code. It is beneficial to modify K (black) for the generation of the concealed code as modification of the amount of black does not change the hue of the color, but enhances the contrast.

[0117] With “Y (yellow) and / or K (black) are most modified for the generation of the concealed code” is preferably meant in more pixels of the decorative pattern the volume of Y ink and / or the volume of K ink is modified compared to the amount of pixels in which the volume of the other spot colors is modified.

[0118] A preferred embodiment is characterized in that the code is generated without modification of the spot color least used in the decorative pattern.

[0119] Such embodiment minimizes the risk of not fully concealing the code, as changes to spot colors not used much would be more visible to the human eye than modifications of spot colors used much in the generation of the code.

[0120] A preferred embodiment is characterized in that the code the decorative pattern is a wood decor, and that the code is substantially oriented parallel with the wood grain.

[0121] Such embodiment allows better concealing of the code.

[0122] A preferred embodiment is characterized in that the concealed code is introduced in the decorative pattern in a stage wherein the decorative pattern is available in CMYK color profile, in CRYK color profile or in X-color spot color profile.

[0123] With “X” in X-color spot color profile is meant the number of spot colors in the spot color profile. “X” can e.g. be 8, meaning an 8 color spot co or lor. CMYK and CRYK systems are 4 color spot colors. Preferably, “X” is identical to 4, 8 or 10.

[0124] Introducing the decorative pattern in a stage wherein the decorative pattern is available in CMYK color profile, in CRYK color profile or in X-color spot color profile has the benefit that optimally limitations can be taken into account related to which of the inkjet inks should least, not or most be modified in creating the concealed code, wherein also the decorative pattern in itself can be taken into account.

[0125] The decorative pattern can in this respect already be available in CMYK color profile, in CRYK color profile or in X-color spot color profile as early as the first master decor or the second master decor or in any step thereafter.

[0126] In a preferred embodiment, the concealed code can be read via electronic means, e.g. with an app on a smartphone.

[0127] In a preferred embodiment, reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on the composition of the decorative panel comprising the printed decorative pattern.

[0128] In a preferred embodiment, reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on methods of recycling the decorative panel comprising the printed decorative pattern.

[0129] Such embodiments have the benefit that after use and disposal of a decorative panel comprising the printed decorative pattern, the information of methods of recycling is easily available. The decorative panel can be more easily recycled, preventing the decorative panel from being incinerated or put in landfill.

[0130] In a preferred embodiment, reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on the authentication of the decorative panel comprising the printed decorative pattern.

[0131] In a preferred embodiment, reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on maintenance instructions (e.g. cleaning instructions) of the decorative panel comprising the printed decorative pattern. In a preferred embodiment, reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on the manufacturer of the decorative panel comprising the printed decorative pattern.

[0132] In a preferred embodiment, reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on installation instructions and / or cleaning instructions of the decorative panel comprising the printed decorative pattern.

[0133] In a preferred embodiment, reading the concealed code via electronic means, e.g. with an app on a smartphone, serves anti-counterfeit purpose of the decorative panel comprising the printed decorative pattern.

[0134] In a preferred embodiment, reading the concealed code via electronic means, e.g. with an app on a smartphone, establishes direct contact between a person reading the concealed code - e.g. a customer intending to purchase or who purchased the decorative panel comprising the printed decorative pattern - and the manufacturer or distributor of the decorative panel comprising the printed decorative pattern.

[0135] Such embodiment facilitates the exchange of information between manufacturer or distributor on the one hand, and on the other hand a customer or person interested to buy the product.

[0136] It is well known to add information or codes - such as QR-codes - that after reading direct to information on a website on packaging material of decorative panels. However, after installation, most of time the packaging material is discarded. The invention ensure that the concealed code in the decorative pattern can still be read on the product itself. Consequently, the concealed code can be read over the entire lifetime of the product. The concealed code can even be read after removal of the product (e.g. after removal of the decorative panels from a floor covering). This can be of interest for reading information via the concealed code on product composition (for recycling purposes) or on methods of recycling. An eighth aspect of the invention is a method for printing with a digital printer a decorative pattern comprising a concealed code, wherein the method comprises the step of using a control file for printing with the digital printer the decorative pattern comprising the concealed code, wherein the control file is generated according to a method as in any of embodiment of the first aspect of the invention, of the second aspect of the invention, of the third aspect of the invention, of the fourth aspect of the invention, of the fifth aspect of the invention, of the sixth aspect of the invention or of the seventh aspect of the invention.

[0137] Preferably, the digital printed is a single-pass inkjet printer.

[0138] A preferred embodiment of the invention is characterized in that the decorative pattern is printed on a sheet or on a board.

[0139] The sheet can be a sheet of paper, which can after printing be impregnated with a thermosetting resin, e.g. a melamine formaldehyde resin. The impregnated printed sheet of paper can be laminated - e.g. by means of direct pressure lamination - onto a wood fiber panel. During the lamination, a surface texture can be pressed in register with the printed decorative pattern. The decorative pattern can e.g. be a wood pattern.

[0140] The sheet can be a thermoplastic foil, e.g. a polyvinylchloride (PVC) foil, a polyethylene (PE) foil, a polypropylene (PP) foil, or a polyester foil. The foil can preferably have a thickness ranging between 40 micron and 200 micron. The foil can after printing be laminated onto a board, preferably onto a synthetic board (e.g. a PVC based board) or onto a mineral board. Lamination of the foil onto a synthetic board can e.g. be performed via thermal lamination.

[0141] The board can be a ceramic board, a quartz board or an engineered stone board. The board can be printed before the board is baked or cured.

[0142] Water-based inks, even more preferably pigmented water-based inks, can be used in embodiments of the invention thanks to their low cost. Solvent-based inks, oil-based inks, UV curing inks or hydro-UV inks can be used in embodiments of the invention.

[0143] With the intention of better showing the characteristics of the invention, hereafter, as an example without any limitative character, several preferred embodiments are described, with reference to the accompanying drawings, wherein: figure 1 shows a decorative panel comprising a concealed code generated according to a method according to the invention; figure 2a and 2b shows the surface of a decorative panel comprising a concealed code generated according to a method according to the invention; and figure 3 shows as an example steps in the process for printing a decorative pattern on a digital printer.

[0144] Figure 1 shows a decorative panel 1 comprising a concealed code generated according to a method according to the invention. The decorative panel 1 comprises a board 2 and a decorative top layer 3. The decorative top layer comprises a digitally printed decorative pattern, and optionally a surface texture, e.g. a texture in register with the digitally printed decorative pattern.

[0145] The board can e.g. be a wood fiber panel, and the decorative top layer can comprise a sheet of paper comprising the digitally printed decorative pattern. The printed sheet of paper is impregnated with a thermoset resin, e.g. a melamine formaldehyde resin. The impregnated printed sheet of paper can have been laminated by means of direct pressure lamination onto the wood fiber panel. During the direct pressure lamination, a surface texture in register with the printed decorative pattern can be created. The decorative pattern can e.g. be a wood pattern.

[0146] The board can be a polyvinyl chloride board and the decorative top layer can comprise a polyvinyl chloride foil which has been digitally printed with the decorative pattern. The polyvinyl chloride foil has been thermally laminated onto the substrate. Optionally, a surface texture is provided, optionally in register with the printed decorative pattern. The decorative pattern can e.g. be a wood pattern.

[0147] The board can be a ceramic board, wherein the decorative pattern has been printed on the ceramic board before it has been fired in the kiln.

[0148] Other boards and carriers of the digitally printed decorative pattern are possible according to the invention.

[0149] Figure 2a and 2b show the decorative surface of a panel 1 shown in figure 1. Figure 2a shows the decorative surface as observed by the human eye. The example shows a panel 1 having a digitally printed decorative pattern representing a wood decor, digitally printed using a CRYK inkjet ink color set. The digitally printed decorative pattern however has been modified such that it comprises a concealed code 50 invisible to the human eye but machine readable.

[0150] Figure 2b shows the concealed code as read by an app on a smartphone. In the example shown, the code is a steganographic code, which is continuously repeated of the full decorative pattern of the panel 1. The code is composed of a pattern of squares. The code is composed of a series of clusters of pixels, wherein each pixel in a cluster of pixels having the same color. In incorporating the concealed code in the decorative pattern originally designed, in the example only the volumes of Y ink and of K ink have been modified.

[0151] Figure 3 shows as an example steps in the process for printing a decorative pattern on a sheet on a digital printer, e.g. on a single-pass inkjet printer. In step A, a decorative pattern is created, this activity is in in essence a design activity. The first master decor 10 is thereby generated as a digital file.

[0152] In step B, banding compensation is performed. Banding compensation comprises the step of modifying the first master decor to compensate for variable density output of the individual printheads of the digital printer to be used for printing the decorative pattern on the sheet. The banding compensation results in a digital file 12 comprising the first master decor after banding.

[0153] Step C comprises the steps of

[0154] - printing the first master decor (using the file 12 obtained after banding compensation) showing the decorative pattern on a first sample of the sheet, thereby obtaining a first sample sheet comprising the first master decor;

[0155] - performing a process on the first sample sheet comprising the first master decor, wherein the process causes a deformation of the printed first master decor on this first sample sheet;

[0156] - measuring this deformation on the first sample sheet;

[0157] - modifying the first master decor thereby obtaining a second master decor 14, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process.

[0158] In step D the file 14 comprising the second master decor is converted to the control file 16 for controlling a digital printer - e.g. an inkjet printer - for printing the second master decor in step E.

[0159] Each of the digital files the first master decor 10, the first master decor after banding compensation 12, the second master decor 14 and the control file 16 can be in CMYK color profile, in CRYK color profile or in X-color spot color profile.

[0160] Alternatively, the first master decor 10; and / or the first master decor after banding compensation 12, and / or the second master decor 14 can be in another color profile, and a conversion is performed to CMYK color profile, to CRYK color profile or to X-color spot color profile after step A, after step B, after step C or after step D.

[0161] The concealed code can be introduced in the digital files according to the embodiments described in the claims and in the description of the invention. The concealed code can be introduced in the first master decor 10, or in the first master decor after banding compensation 12, or in the second master decor 14, or in the control file 16 As an alternative to the example of the method as explained above, step C can be performed in an alternative way. Step C can comprise the steps

[0162] - providing printable first sample of the sheet, thereby obtaining a first sample sheet.

[0163] - performing a process on the first sample sheet, wherein the process causes a deformation on this first sample sheet;

[0164] - measuring this deformation on the first sample sheet;

[0165] - modifying the first master decor thereby obtaining a second master decor 14, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process.

[0166] In this method, a printable firs sample of the sheet is provided. This means a sheet that is ready for printing, but does not need to be printed. An example is a sheet of paper comprising a primer that makes it suitable for digital printing.

[0167] Instead of a printable first sample of the sheet, the first sample sheet can be a printed first sample of the sheet. As already mentioned, the first sample sheet can be printed with the first master decor. However, the first sample sheet can alternatively be printed with another pattern, e.g. with marks that facilitate the measurement of the deformation of the first sample sheet after performing the process. Such marks can e.g. include straight lines or straight line segments on predetermined distance from each other.

[0168] The present invention is in no way limited to the embodiments described as an example and represented in the figures, on the contrary it can be realized in various forms and dimensions, without leaving the scope of the invention.

Claims

Claims1.- Method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a sheet, wherein the decorative pattern is modified such that it comprises a concealed code; wherein the method comprises the steps of- printing a first master decor showing the decorative pattern on a first sample of the sheet, thereby obtaining a first sample sheet comprising the first master decor;- performing a process on the first sample sheet comprising the first master decor, wherein the process causes a deformation of the printed first master decor on this first sample sheet;- measuring this deformation on the first sample sheet;- modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process;- generating a control file for a digital printer for printing the second master decor on a sheet having the same characteristics as the first sample sheet; characterized in that the printed second master decor comprises the concealed code invisible to the human eye but machine readable.2.- Method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a sheet, wherein the decorative pattern is modified such that it comprises a concealed code; wherein the method comprises the steps of- providing a printed or printable first sample of the sheet, thereby obtaining a first sample sheet;- performing a process on the first sample sheet, wherein the process causes a deformation on this first sample sheet;- measuring this deformation on the first sample sheet;- providing a first master decor comprising the decorative pattern;- modifying the first master decor thereby obtaining a second master decor, wherein thesecond master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process;- generating a control file for a digital printer for printing the second master decor on a sheet having the same characteristics as the first sample sheet; characterized in that the printed second master decor comprises the concealed code invisible to the human eye but machine readable.3.- Method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a sheet, wherein the decorative pattern is modified such that it comprises a concealed code; wherein the method comprises the steps of- providing a first master decor comprising the decorative pattern;- modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for expected deformation occurring in processes the sheet undergoes after being printed with the decorative pattern;- generating a control file for a digital printer for printing the second master decor on a sheet having the same characteristics as the first sample sheet; characterized in that the printed second master decor comprises the concealed code invisible to the human eye but machine readable.4.- Method as in any of the claims 1 - 3, characterized in that the concealed code is added to the decorative pattern before the step of modifying the first master decor thereby obtaining the second master decor.5.- Method as in any of the claims 1 - 3, characterized in that the method comprises the step of banding compensation before the step of modifying the first master decor thereby obtaining the second master decor; wherein the step of banding compensation comprises the step of modifying the first master decor to compensate for variable density output of the individual printheads of the digital printer to be used for printing the decorative pattern on the sheet;wherein the concealed code is added to the decorative pattern before the step of banding compensation.6.- Method as in any of the claims 1 - 4, characterized in that the method comprises the step of banding compensation before the step of modifying the first master decor thereby obtaining the second master decor; wherein the step of banding compensation comprises the step of modifying the first master decor to compensate for variable density output of the individual printheads of the digital printer to be used for printing the decorative pattern on the sheet; wherein the concealed code is added to the decorative pattern after the step of banding compensation.7.- Method as in any of the claims 1 - 3, characterized in that the concealed code is added to the decorative pattern after the step of modifying the first master decor thereby obtaining the second master decor.8.- Method as in claim 7, characterized in that the concealed code is added to the decorative pattern before the step of generating the control file for a digital printer for printing the second master decor on a sheet having the same characteristics as the first sample sheet.9.- Method as in claim 7, characterized in that the method comprises the step of incorporating the concealed code into the control file after a control file has been generated from the second master decor.10.- Method as in any of the preceding claims, characterized in that said process comprises one or a plurality of process steps which the printed sheet will undergo for use as decorative layer of a decorative panel; preferably wherein the decorative layer of the decorative panel comprises a surface texture, preferably a surface texture in register with the decorative pattern of the decorative layer.11.- Method as in any of the preceding claims 1 - 10, characterized in that the sheet is a sheet of paper.12.- Method as in claim 11, characterized in that said process comprises the impregnation of the sheet of paper with a resin, preferably with a thermosetting resin.13.- Method as in any of the preceding claims 1 - 10, characterized in that the sheet is a thermoplastic foil, e.g. a polyvinylchloride (PVC) foil, a polyethylene (PE) foil, a polypropylene (PP) foil, or a polyester foil.14.- Method as in claim 13, characterized in that the process comprises the lamination- preferably the thermal lamination - of the thermoplastic foil onto a board, preferably onto a synthetic board or onto a mineral board; or in that the process comprises the lamination - preferably the thermal lamination - of a transparent thermoplastic foil on the printed thermoplastic foil.15.- Method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a board, wherein the decorative pattern is modified such that it comprises a concealed code; wherein the method comprises the steps of- printing a first master decor showing the decorative pattern on a first sample of the board, thereby obtaining a first sample board comprising the first master decor;- performing a process on the first sample board comprising the first master decor, wherein the process causes a deformation of the printed first master decor on this first sample board;- measuring this deformation on the first sample board;- modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process;- generating a control file for a digital printer for printing the second master decor on a board having the same characteristics as the first sample board;characterized in that the printed second mater decor comprises the concealed code invisible to the human eye but machine readable.16.- Method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a board, wherein the decorative pattern is modified such that it comprises a concealed code; wherein the method comprises the steps of- providing a printed or printable first sample of the board, thereby obtaining a first sample board;- performing a process on the first sample board, wherein the process causes a deformation of first sample board;- measuring this deformation on the first sample board;- - providing a first master decor comprising the decorative pattern;- modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for the deformation occurring in said process;- generating a control file for a digital printer for printing the second master decor on a board having the same characteristics as the first sample board; characterized in that the printed second mater decor comprises the concealed code invisible to the human eye but machine readable.17.- Method for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a board, wherein the decorative pattern is modified such that it comprises a concealed code; wherein the method comprises the steps of- providing a first master decor comprising the decorative pattern;- modifying the first master decor thereby obtaining a second master decor, wherein the second master decor is modified compared to the first master decor such that it compensates for expected deformation occurring in processes the sheet undergoes after being printed with the decorative pattern;- generating a control file for a digital printer for printing the second master decor on a board;characterized in that the printed second mater decor comprises the concealed code invisible to the human eye but machine readable.18.- Method as in any of the preceding claims 15 - 17, characterized in that the board is a ceramic board, a quartz board or an engineered stone board before or after the board is baked or cured.19.- Method as in any of the preceding claims 15 - 17, characterized in that the concealed code is added to the decorative pattern before the step of modifying the first master decor thereby obtaining the second master decor.20.- Method as in any of the preceding claims 15 - 19, characterized in that the method comprises the step of banding compensation before the step of modifying the first master decor thereby obtaining the second master decor; wherein the step of banding compensation comprises the step of modifying the first master decor to compensate for variable density output of the individual printheads of the digital printer to be used for printing the decorative pattern on the sheet; wherein the concealed code is added to the decorative pattern before the step of banding compensation.21.- Method as in any of the preceding claims 15 - 19, characterized in that the method comprises the step of banding compensation before the step of modifying the first master decor thereby obtaining the second master decor; wherein the step of banding compensation comprises the step of modifying the first master decor to compensate for variable density output of the individual printheads of the digital printer to be used for printing the decorative pattern on the sheet; wherein the concealed code is added to the decorative pattern after the step of banding compensation.22.- Method as in any of the preceding claims 15 - 18, characterized in that the concealed code is added to the decorative pattern after the step of modifying the first master decor thereby obtaining the second master decor.23.- Method as in claim 22, characterized in that the concealed code is added to the decorative pattern before the step of generating a control file for a digital printer for printing the second master decor on a board having the same characteristics as the first sample board.24.- Method as in claim 22, characterized in that the method comprises the step of incorporating the concealed code into the control file after a control file has been generated from the second master decor.25.- Method as in any of the preceding claims 15 - 24, characterized in that said process comprises one or a plurality of process steps which the printed board will undergo in the process of producing a decorative panel or decorative tile from it.26.- Method - optionally a method as in any of the preceding claims - for generating a control file for a digital printer, wherein the control file is provided for printing a decorative pattern on a substrate, wherein the decorative pattern is modified such that it comprises a concealed code invisible to the human eye but machine readable.27.- Method as in claim 26, characterized in that a first control file is generated for printing the decorative pattern without concealed code, followed by the step of modification of the control file such that the decorative pattern to be printed comprises the concealed code.28.- Method as in any of the previous claims, characterized in that the decorative pattern is a wood pattern.29.- Method as in any of the previous claims, characterized in that the concealed code is continuously repeated over the full decorative pattern.30.- Method as in any of the preceding claims, characterized in that the code is a steganographic code.31.- Method as in any of the preceding claims, characterized in that the printed code is composed of a pattern of squares and / or rectangles.32.- Method as in any of the preceding claims, characterized in that the printed code is composed of a series of clusters of pixels, wherein each pixel in a cluster of pixels has the same color.33.- Method as in any of the preceding claims, characterized in that the printed code comprises or is composed of missing dots in the decorative pattern.34.- Method as in any of the preceding claims 1 - 33, characterized in that the control file provides instructions for a digital printer for printing with spot colors - e.g. with 4, 8 or 10 spot colors -, wherein the code is created by modification of less than 4 of the spot colors, preferably of less than 3 of the spot colors, and preferably of only 2 of the spot colors.35.- Method as in any of the preceding claims 1 - 34, characterized in that the decorative pattern and the concealed code are printed by means of digital printing using the same four color inkset, e.g. a CMYK inkjet ink set or a CRYK inkjet ink set.36.- Method as in claim 34 or 35, characterized in that the concealed code is generated by modifying only one, only two or only three of the spot colors.37.- Method as in any of the preceding claims 35 - 36, characterized in that C (cyan) is less modified for the generation of the concealed code than at least Y (yellow) and / or K (black) when using the CMYK inkjet ink set or when using the CRYK inkjet ink set.38.- Method as in any of the preceding claims 35 - 37, characterized in that C (cyan) is not modified for the generation of the concealed code.39.- Method as in any of the preceding claims 35 - 38, characterized in that Y (yellow) and / or K (black) are most or exclusively modified for the generation of the concealed code.40.- Method as in any of the preceding claims 35 - 39, characterized in that the code is generated without modification of the spot color least used in the decorative pattern.41.- Method as in any of the preceding claims, characterized in that the decorative pattern is a wood decor, and that the code is substantially oriented parallel with the wood grain.42.- Method as in any of the preceding claims, characterized in that the concealed code is introduced in the decorative pattern in a stage wherein the decorative pattern is available in CMYK color profile, in CRYK color profile or in X-color spot color profile.43.- Method as in any of the preceding claims, characterized in that the concealed code can be read via electronic means, e.g. with an app on a smartphone.44.- Method as in claim 43, characterized in that reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on the composition of the decorative panel comprising the printed decorative pattern.45.- Method as in any of the preceding claims 43 - 44, characterized in that reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on methods of recycling the decorative panel comprising the printed decorative pattern.46.- Method as in any of the preceding claims 43 - 45, characterized in that reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on installation instructions and / or cleaning instructions of the decorative panel comprising the printed decorative pattern.47.- Method as in any of the preceding claims 43 - 46, characterized in that reading the concealed code via electronic means, e.g. with an app on a smartphone, serves anticounterfeit purpose of the decorative panel comprising the printed decorative pattern.48.- Method as in any of the preceding claims 43 - 47, characterized in that reading the concealed code via electronic means, e.g. with an app on a smartphone, establishes direct contact between a person reading the concealed code - e.g. a customer intending to purchase or who purchased the decorative panel comprising the printed decorative pattern - and the manufacturer or distributor of the decorative panel comprising the printed decorative pattern.49.- Method for printing with a digital printer a decorative pattern comprising a concealed code, wherein the method comprises the step of using a control file for printing with the digital printer - preferably a single-pass inkjet printer - the decorative pattern comprising the concealed code, wherein the control file is generated according to a method as in any of the preceding claims.50.- Method as in claim 49, characterized in that the decorative pattern is printed on a sheet or on a board.

Images