Method for creating a digitally printed décor comprising a concealed code, a method for manufacturing a ceramic slab comprising a concealed code and ceramic slab comprising a concealed code

Abstract

A method for generating a master image for decorating a ceramic slab (1), the master image being configured for printing a decorative pattern on a ceramic slab, the decorative pattern can be modified such that it comprises a concealed code, the method can comprise the steps of: - providing a first master image (10) of the decorative pattern in a first color space, for example a CMYK or a RGB color space; - converting the first master image (10) from the first color space in a second master image (12) of the decorative pattern in a second color space; the second master image includes the concealed code (50) in the decorative pattern.

Description

[0001] Method for creating a digitally printed decor comprising a concealed code, a method for manufacturing a ceramic slab comprising a concealed code and ceramic slab comprising a concealed code.

[0002] The present invention relates to a method for generating a master image for decorating a ceramic slab, wherein the master image is provided for printing a decorative pattern on a ceramic slab, wherein the decorative pattern is modified such that it comprises a concealed code. A ceramic slab printed with a decorative pattern comprising the concealed code can be used for decorative surfaces, e.g. a floor boards. 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 a challenge to ensure that the concealed code doesn’t disturb the visual aspect of the ceramic slab. 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.

[0005] Thereto, the present invention, according to its first independent aspect, relates to a method for generating a master image for decorating a ceramic slab. The master image can be configured for printing a decorative pattern on a ceramic slab. The decorative pattern can be modified such that it comprises a concealed code. The method can comprise the steps of

[0006] - Providing a first master image of the decorative pattern in a first color space, for example a CMYK or a RGB color space;

[0007] Converting the first master image from the first color space in a second master image of the decorative pattern in a second color space;

[0008] The second master image includes the concealed code in the decorative pattern.

[0009] In the preferred embodiment the method can comprise the step of applying the concealed code into the second master image after performing said conversion from the first color space to the second color space. In this way it is possible to prevent some undesired problems caused by the conversion of the concealed code itself from the first to the second color space like, for example a reduced readability of the concealed code itself, loss of information and / or undesired color shift which could result in a loss of definition of the decorative pattern. The second color space can be a printing color space defined by at least 4 colors or inks, preferably more than 4 colors or inks, for example between 4 and 12 colors or inks. In some embodiments, the second color space differs from a CMYK or RGB color space. In some embodiments, amongst the colors defining the second color space is excluded color magenta. Magenta is a standard color for digital printing, being one of the primary colors; consequently, also image editing programs are usually set to work in CMYK color space. On the other hand, magenta is a not an available color for ceramic digital printing (at least for ceramic with firing temperature above 1000°C), as there are no available pigments that withstand the firing temperature. By applying the concealed code in the second color space it could be possible to make sure that the application of concealed code involving magenta doesn’t get loss during conversion. Preferred colors defining the second color space can comprise cyan, blue, red, brown, pink, yellow, honey, beige, orange, black, purple, green and / or white. Preferably the inks of said colors comprise a pigment in the form of metal oxides

[0010] In the preferred embodiment the second color space can be defined by colors in combination with digital material effect inks. For the sake of the invention with material effect ink it is meant an ink that is jetted during printing and is directed to provide a decorative effect that differs from pure color, for example matte, glossy, metal, luster or relief effect. These kinds of inks are also often referred to in the ceramic industries as “materic” effect, wherein this word derives from Italian or Spanish “materico”. In this way the concealed code can be formed by a pattern of material effects on the surface of the ceramic slab which can be less noticeable by human eyes than a pattern of colors. For example, said concealed code can be formed by a pattern of spots having a different gloss degree, or by a pattern of depressions on the surface of the ceramic slab.

[0011] Material effect inks for obtaining a relief can comprise a sinker (or sinking agent) which is a substance that cause forming of depression in a glaze layer of a ceramic slab, and / or a structurer (also known as carver or repellent) which repels a glaze layer substance forming an excavation, and / or a glue which through interaction with a subsequently provided powder or grit, will cause the forming of relief.

[0012] In a preferred, embodiments material effect inks comprise glossy inks and / or matte inks. Glossy inks are inks comprising a substance, preferably a metal oxide and / or a metal complex, adapted to locally increase the gloss degree on the surface of the final ceramic slab. For example, said glossy ink can comprise a metal oxide and / or a metal complex adapted to increase the refraction index on the surface of the slab on the spot the glossy inks are printed. For example, said glossy ink can comprise barium oxide (BaO). Matte inks are inks comprising a substance, preferably a metal oxide and / or a metal complex, adapted to locally decrease the gloss degree on the surface of the final ceramic slab. For example, said matte inks can comprise a metal oxide and / or a metal complex adapted to reduce the refraction index and / or cause a devitrification (for example a crystallization) on the surface of the slab on the spot the matte inks are printed. For example, said matte inks can comprise tin oxide (SnO2) and / or zirconium oxide (ZrO2).

[0013] Preferably, applying the concealed code in a master image can involve modifying jetting information of one or more of color or inks defining the second color space or in any case printable by the printer. For example, applying the concealed code in a master image can involve modifying jetting information of only one of said color or inks defining the second color space.

[0014] In one preferred embodiment, applying the concealed code in the second master image can involve modifying jetting information of one or more wherein digital material effect inks. In this way the concealed code is not obtained through modification of the color and its impact on the final decorative pattern can be minimized.

[0015] In a preferred embodiment, the method can involve printing a test pattern on a sampling slab in said second color space, performing an operation on said sampling slab that can cause a color variation in said test pattern, and modify said second master image to compensate said color variation. Said operation can comprise firing of the sampling slab in an kiln at a firing temperature substantially equal to the firing temperature of the ceramic slab. It is noted that, during firing of the ceramic slab several physical and / or chemical transformation occur, causing the color development and / or the reaction of the material effect inks so that the ceramic slab obtains the final appearance. Nevertheless, the results of said transformations depends on several factors including, for example, composition of raw materials for manufacturing ceramic slabs, composition of atmosphere in the kiln etc., so that the final color or material effect can differ from the desired. Therefore, the second master image can be modified to compensate the expected color variation observed on the sampling slab. Said modification of the second master image can involve in an image editing operation performed by an operator on an image editing software, for example Gimp® or Photoshop®. In some embodiments, the concealed code can be applied to the modified second master image, i.e. it is applied on the second master image after said modification is performed.

[0016] A preferred embodiment 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 or removed. Such is the case with floor slabs or floor tiles when a the tile is cut during installation. In the invention, the concealed code is preferably a steganographic code. 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.

[0017] A preferred embodiment is characterized in that the printed code is composed of a pattern of squares and or rectangles. This way, easy readable concealed codes can be built, e.g. QR-type codes.

[0018] 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.

[0019] A preferred embodiment is characterized in that the printed code comprises or is composed of missing dots in the decorative pattern. 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.

[0020] Preferably, the concealed code can be read via electronic means, e.g. with an app on a smartphone or with a software on computer connected to a reader, preferably an optical reader.

[0021] In some embodiments, reading the concealed code via electronic means, e.g. with an app on a smartphone, may return information on the composition of the ceramic slab comprising the printed decorative pattern. In some embodiments, reading the concealed code via electronic means, e.g. with an app on a smartphone, may return information on methods of recycling the ceramic slab comprising the printed decorative pattern. In some embodiments, reading the concealed code via electronic means, e.g. with an app on a smartphone or with a software on a computer connected to an optical reader, may return information on installation instructions and / or cleaning instructions of the ceramic slab comprising the printed decorative pattern.

[0022] According to an important embodiment of the invention, reading the concealed code via electronic means, e.g. with an app on a smartphone, returns manufacturing, product or quality information - e.g. identification of production batch or production plant, identification of country of origin, quality classification, quality certificates - ceramic slab comprising the printed decorative pattern. This can give the opportunity for the manufacturer to collect information that would be otherwise normally lost when the ceramic slab is installed, in case of need, for example for customer service needs. Preferred examples of quality classification in the case of tiles can include shade classification. For reasons connected to the manufacturing process of ceramic tiles or slabs, the color tonality or shade is not always constant and can change from batch to batch, it may then happen that tiles or slab catalogued with a different shade and / or belonging to a different production batch are mixed during installation. Thanks to the concealed code returning this information and being always visible on the slab, even during installation, it may be possible to reduce the risk of mixing the slabs or to show after installation if the slabs belong to the same shade classification or not.

[0023] In some embodiments, reading the concealed code via electronic means, e.g. with an app on a smartphone, could serve anti-counterfeit purpose of the ceramic slab comprising the printed decorative pattern.

[0024] In some embodiments, 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 ceramic slab comprising the printed decorative pattern - and the manufacturer or distributor of the ceramic slab comprising the printed decorative pattern. For example, reading the concealed code via the electronic means permit to connect the electronic means to a virtual information container - e.g. a database or a webpage - containing one or more sets of information.

[0025] In some embodiments, the virtual information container can comprise unalterable set of information and / or alterable set of information. For examples, set of unalterable information can contain info on production batch and / or on quality feature of the product, whereas set of alterable information can comprise contacts information, marketing information or the like.

[0026] For example, said unalterable set of information can be based on blockchain technology. In this way it can be ensured, to the customer for example, that that specific set of information is trustable and reliable.

[0027] According to some embodiments, the concealed code can be read by multiple electronic means, e.g. with one or different apps on a smartphone, or with a software on a computer connected to an optical reader. Preferably, reading the concealed code can return different information depending on the electronic reading mean. In this way, it may be possible that, for example, a first electronic means can be used during manufacturing and the concealed code returns info on the manufacturing process, for example on setting of subsequent steps in the process, or info that tells if the product needs to undergo or not to certain process step; whereas a second electronic means can be used after manufacturing to get access to certain information of the product accessible for the manufacturer or the retailer, but not to the customer, like prices or stock information, available discount policy, etc..; whereas a third electronic means can be used after manufacturing to get access to certain information of the product accessible to the customer, like for example installation, recyclability, etc..

[0028] In the most preferred embodiment, the method of the first aspect of the invention is part of a method for manufacturing a ceramic slab. Said method for manufacturing the ceramic slab involving at least the steps of: printing a decorative pattern on a green ceramic slab; and firing said printed green ceramic slab; wherein the step of printing is performed as per the method of printing described in the preceding paragraphs. In particular, wherein the step of printing involves commanding a printer on the basis of said second master image and / or said modified second master image for printing the decorative pattern, comprising the concealed code, on the green ceramic slab.

[0029] It is noted that within the context of the present invention, the expression “green ceramic slab” refers to a semi product having at least a body formed by a compressed powder material, wherein said powder material has a composition adapted for forming a ceramic material after a firing process. The green slab preferably comprises one or more surface coatings that cover an upper surface of the body. Said decorative pattern is preferably obtained by jetting inks on the uppermost of said surface coatings. Said surface coatings preferably comprise at least one glaze. In case multiple surface coatings are present, it is preferable that each of said surface coatings uniformly covers the upper surface of the body and the said surface coatings are superimposed each other.

[0030] The method for manufacturing the ceramic slab can comprise applying one or more additional coatings on top of the printed decorative pattern. Said additional coating preferably comprise one glaze. Said additional coating preferably being at least partially transparent.

[0031] Said firing step is preferably performed in a kiln wherein the slab is heated and cooled in a firing cycle having a maximum temperature preferably above 1000 °C, preferably 1200°C.

[0032] The method for manufacturing the ceramic slab can comprise additional steps like forming of said body, application of said surface coatings and / or additional coatings, and finishing steps. These additional steps are for example disclosed in WO 2022 / 234352 which is herein incorporated by reference in its entirety. In some embodiment of said method for manufacturing a ceramic slab, it is possible that at least a part of the information returned by reading the concealed code are determined after the step of firing. Preferably, the method can comprise a sorting step for cataloging the product based on quality parameters. Preferably, at least part of said information are determined after said step of sorting. In this way when reading the concealed code, the customer or the installer can immediately check, for example, to which shade classification that specific slab belongs, and the risk of mixing shades is reduced. Preferably, at least a part of said information determined after said step of sorting can be unalterable, for example it can be based on blockchain technology. For example, the concealed code can return information of an address of a determined file stored in a database and / or to a determined storing position in a database, connected to a server, so that when reading the concealed code with a device, said device is allowed to access information contained in said determined file and or in said storing position in the database. The information contained in said file determined file and or in said storing position are filled only determined after the step of firing.

[0033] It is noted that the fact that a part of the returned information connected to the concealed code is determined after the manufacturing of the slab is completed can constitute an invention independently from how the control file is generated and therefore independent from the first independent aspect. It is also noted that said inventive concept can be applied to other kind of decorative element like laminate panels and is not necessarily limited to ceramic slabs. Thereto, according to its second independent aspect the invention can relate to a method for manufacturing a decorative element, for example a ceramic slab or a laminate panel, involving the steps of: forming a decorative part of the decorative element, said decorative part comprising a decorative pattern; and completing the manufacturing of said decorative element; wherein said decorative pattern involves a machine readable concealed code, wherein and reading the concealed code permits to connect the electronic means to a virtual information container - e.g. a database or a webpage - containing one or more sets of information, and wherein at least a part of said set of information is determined after said step of completing the manufacturing of said decorative element. It is noted that the method of the second aspect can comprise one or more of the features discussed for the previous independent aspect.

[0034] It is noted that the fact that a part or the entirety of the concealed code can be obtained through jetting of material effect inks can constitute an invention independently from how the control file is generated as well as from when the information connected to the concealed code are generated, and therefore independent from the first and / or the second independent aspect described above. Therefore, the invention according to its third independent aspect can relates to a method for manufacturing a ceramic slab involving the steps of: printing a pattern on a green ceramic slab; and firing said printed green ceramic slab; wherein said printed pattern includes a concealed code, and wherein said concealed code is formed by jetting digital material effect inks. It is noted that the method of the second aspect can comprise one or more of the features discussed for the previous independent aspects.

[0035] Preferably, digital material effect inks are selected from the list comprising, preferably consisting of: glossy, sinker, structure, matt, metal, luster, glue.

[0036] In a special embodiment of said third independent aspect, the method can comprise a first printing operation for printing a first pattern comprising the concealed code and a second printing operation for printing a second pattern forming the decorative pattern. The first printing operation and the second printing operation can be distinct each other, for example performed in different moment of the manufacturing method, and / or performed by different printers, and / or being separated by one or more steps of the manufacturing method. Sid first printing operation is performed upstream said second printing operation. In this way the concealed code can have no impact at all on the decorative pattern and to the color development thereof. It is noted that in deviant embodiments the first printing operation can be performed downstream said second printing operation. In some embodiments of the third independent aspect, the method comprises a glazing step in between the first and second printing operation, said glaze being preferably opaque. In this case it is preferable that the material effect jetted for forming the concealed code comprises a sinker or a structuring ink. Said first and second printing operations are for example disclosed in WO 2022 / 234352 which is herein incorporated by reference in its entirety. Int his special embodiment, the concealed code, after said step of firing, is in the form of a relief pattern, i.e. a three-dimensional pattern and / or in a pattern of matte and gloss areas, i.e. a pattern of pixels having different gloss degree. Preferably, said concealed code in the form of a relief pattern and / or in a pattern of matte and gloss areas, is still invisible to human eye and / or to haptic feeling. It is further possible that the concealed code in the form of a relief pattern and / or in a pattern of matte and gloss areas represent a regular pattern integrated in a decorative relief pattern and / or in a decorative pattern of matte and gloss areas, so that its regularity is not perceivable. In other words, one or more of the pixels and / or feature of the concealed code could be singularly visible to human eye, but it could be difficult if not impossible to distinct these features from those forming decorative relief pattern and / or in a decorative pattern of matte and gloss areas, so that the concealed code remains unperceivable by human senses.

[0037] With the intention of better showing the characteristics of the invention, in the following, as an example without any limitative character, several preferred forms of embodiments are described with reference to the accompanying drawings, wherein: figure 1 shows a ceramic slab comprising a concealed code generated according to a method according to the invention; figure 2a and 2b shows the surface of the ceramic slab 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.

[0038] Figure 1 shows a ceramic slab 1, for example a floor or wall tile, comprising a decorative pattern having a concealed code and printed in a method according to the invention. The ceramic slab 1 comprises a base body 2, made of a ceramic material, for example porcelain stoneware, and a decorative top layer 3. The decorative top layer 3 comprises a digitally printed decorative pattern, and optionally a surface texture, possibly a texture in register with the digitally printed decorative pattern.

[0039] The top layer 3 is a glaze coating and preferably comprises a base glaze coating forming the background for the decorative pattern and a transparent coating coating for protecting the decorative pattern printed on top of the base glaze coating.

[0040] Figure 2a and 2b show the decorative surface of the ceramic slab 1 shown in figure 1. Figure 2a shows the decorative surface as observed by the human eye. The example shows that the ceramic slab 1 has a digitally printed decorative pattern representing a stone decor having a generally matte finish. The decorative pattern is digitally printed using a ceramic inkjet ink set, preferably comprising 12 inks. In the example, the ink set comprises color inks, preferably selected from cyan, blue, red, brown, pink, yellow, honey, beige, orange, black, purple, green and white, and material inks, in the example preferably gloss and matte inks. The top layer 3 shows a generally matte surface finish.

[0041] 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.

[0042] 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 slab 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 only the volumes of yellow ink and of black ink have been modified, alternatively only the glossy and / or the matte ink can be varied in volume for printing the concealed code.

[0043] Figure 3 shows, as an example, some steps in the process for printing a decorative pattern on a surface of a green ceramic tile, e.g. on a single-pass inkjet printer. In step A, a decorative pattern is created, and a first master image 10 is generated. This activity is in essence a design activity, possibly starting from the scanned image of a real natural stone to be imitated. The first master image 10 is preferably in a first color space, for example RGB.

[0044] In step B, a second master image 12 is formed wherein the first master image 10 is converted from the first color space to a second color space, being a printing color space defined by the 12 ceramic inks.

[0045] Step C comprises the steps of:

[0046] - printing the second master image 12 showing the decorative pattern on a first sampling slab, thereby obtaining a first sampling green slab comprising the decorative pattern; alternatively, instead of the second master image a chart comprising multiple color spots, said color spots defining the second color space;

[0047] - firing the sampling green slab having the decorative pattern and / or the color chart, possibly with the same firing cycle and in the same firing kiln for forming the ceramic slab;

[0048] - measuring a color variation between a value of color coordinates measured on the sampling slab after firing and an expected color coordinates;

[0049] - modifying the second master image thereby obtaining a modified second master image 14, wherein the modified second master decor is modified compared to the second master image 12 such that it compensates for the color variation occurring during firing.

[0050] In step D the concealed code is introduced in the digital file of the modified master image 14.

[0051] 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.

[0052] Further, as is clear from the content of the description, the present invention relates to one or more of the items as listed below: 1. A method for generating a master image for decorating a ceramic slab, the master image being configured for printing a decorative pattern on a ceramic slab, the decorative pattern can be modified such that it comprises a concealed code, the method can comprise the steps of: providing a first master image of the decorative pattern in a first color space, for example a CMYK or a RGB color space; converting the first master image from the first color space in a second master image of the decorative pattern in a second color space; the second master image includes the concealed code in the decorative pattern.

[0053] 2. The method according to item 1, wherein a step of applying the concealed code into the decorative pattern after performing said conversion from the first color profile to the second color profile.

[0054] 3. The method according to item 1 or 2, wherein it comprises printing a test pattern on a sampling slab in said second color space, performing an operation on said sampling slab that causes a color variation in said test pattern, and modify said second master image to compensate said color variation.

[0055] 4. The method according to item 3, wherein said operation can comprise firing of the sampling slab in an kiln at a firing temperature substantially equal to the firing temperature of the ceramic slab.

[0056] 5. The method according to item 3 or 4, wherein the concealed code is applied on the second master image after said modification is performed.

[0057] 6. The method according to any of the preceding items, wherein the second color space is a printing color space defined by at least 4 colors or inks, preferably more than 4 colors or inks, for example between 4 and 12 colors or inks.

[0058] 7. The method according to any of the preceding items, wherein the second color space differs from a CMYK or RGB color space. 8. The method according to any of the preceding items, wherein the second color space is defined two or more colors selected from the list comprising, preferably consisting of: cyan, blue, red, brown, pink, yellow, honey, beige, orange, black, purple, green and white.

[0059] 9. The method according to any of the preceding items, wherein the second color space is defined by colors in combination with digital material effect inks, wherein digital material effect inks are selected from the list comprising, preferably consisting of: glossy, sinker, structure, matt, metal, luster, glue.

[0060] 10. The method according to item any of the preceding items, wherein said colors or inks defining the color space are selected from the group comprising, preferably consisting of: cyan, blue, red, brown, pink, yellow, honey, beige, orange, black, purple, green, glossy, sinker, structure, matt, metal, luster, glue and white.

[0061] 11. The method according to any of the preceding items, wherein applying the concealed code in a master image involves modifying jetting information of one or more of inks defining the second color space.

[0062] 12. The method according to any of the preceding items, wherein applying the concealed code in a master image involves modifying jetting information of only one of said color or inks defining the second color space.

[0063] 13. The method according to any of items from 9 to 12, wherein applying the concealed code in a master image involves modifying jetting information of one or more digital material effect inks.

[0064] 14. The method according to any of the preceding items, wherein the concealed code is continuously repeated over the full decorative pattern. 15. The method according to any of the preceding items, wherein the concealed code is a steganographic code.

[0065] 16. The method according to any of the preceding items, wherein the printed code is composed of a pattern of squares and / or rectangles.

[0066] 17. The method according to any of the preceding items, wherein the printed code is composed of a series of clusters of pixels, wherein each pixel in a cluster of pixels has the same color.

[0067] 18. The method according to any of the preceding items, wherein the printed code comprises or is composed of missing dots in the decorative pattern.

[0068] 19. The method according to any of the preceding items, wherein the concealed code can be read via electronic means, e.g. with an app on a smartphone.

[0069] 20. The method according to item 19, wherein reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on the composition of the ceramic slab comprising the printed decorative pattern.

[0070] 21. The method according to items 19 or 20, wherein reading the concealed code via electronic means, e.g. with an app on a smartphone, returns information on methods of recycling the ceramic slab comprising the printed decorative pattern.

[0071] 22. The method according to any of items from 19 to 21, wherein reading the concealed code via electronic means, e.g. with an app on a smartphone or with a software on a computer connected to an optical reader, returns information on installation instructions and / or cleaning instructions of the ceramic slab comprising the printed decorative pattern.

[0072] 23. The method according to any of items from 19 to 22, wherein reading the concealed code via electronic means, e.g. with an app on a smartphone, returns manufacturing, product or quality information - e.g. identification of production batch or production plant, identification of country of origin, quality classification, quality certificates - ceramic slab comprising the printed decorative pattern.

[0073] 24. The method according to any of items from 19 to 23, wherein reading the concealed code via electronic means, e.g. with an app on a smartphone, serves anticounterfeit purpose of the ceramic slab comprising the printed decorative pattern.

[0074] 25. The method according to any of items from 19 to 24, wherein 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 ceramic slab comprising the printed decorative pattern - and the manufacturer or distributor of the ceramic slab comprising the printed decorative pattern.

[0075] 26. The method according to any of items from 19 to 25, wherein reading the concealed code via permit to connect the electronic means to a virtual information container - e.g. a database or a webpage - containing one or more sets of information.

[0076] 27. The method according to item 26, wherein the virtual information container can comprise unalterable set of information and / or alterable set of information.

[0077] 28. The method according to item 27, wherein said unalterable set of information can be based on blockchain technology.

[0078] 29. The method according to any of items from 19 to 28, wherein the concealed code can be read by multiple electronic means, e.g. with one or different apps on a smartphone, or with a software on a computer connected to an optical reader.

[0079] 30. The method according to any of items from 19 to 29, wherein reading the concealed code returns different information depending on the electronic reading mean. 31. Method for printing with a digital printer a decorative pattern comprising a concealed code, wherein the method comprises the step of using a master image 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 items.

[0080] 32. A method for manufacturing a ceramic slab involving the steps of: printing a decorative pattern on a green ceramic slab; and firing said printed green ceramic slab; wherein the step of printing is performed according to the method of item 31.

[0081] 33. The method according to item 32, wherein the concealed code is machine readable and reading the concealed code permits to connect the electronic means to a virtual information container - e.g. a database or a webpage - containing one or more sets of information.

[0082] 34. The method according to item 33, wherein at least part of said information are determined after said step of firing.

[0083] 35. The method according to any of items from 32 to 34, wherein the method comprises a sorting step for cataloging the product based on quality parameters.

[0084] 36. The method according to item 35, wherein at least part of said information are determined after said step of sorting.

[0085] 37. The method according to item 36, wherein at least a part of said information determined after said step of sorting is unalterable.

[0086] 38. The method according to item 37, wherein said unalterable information can be based on blockchain technology.

Claims

Claims1. A method for generating a master image for decorating a ceramic slab (1), the master image being configured for printing a decorative pattern on a ceramic slab, the decorative pattern can be modified such that it comprises a concealed code, the method can comprise the steps of: providing a first master image (10) of the decorative pattern in a first color space, for example a CMYK or a RGB color space; converting the first master image (10) from the first color space in a second master image (12) of the decorative pattern in a second color space; the second master image includes the concealed code (50) in the decorative pattern.

2. The method according to claim 1 , wherein the step of applying the concealed code (50) into the decorative pattern is performed after performing said conversion from the first color space to the second color space.

3. The method according to claim 1 or 2, wherein it comprises printing a test pattern on a sampling slab in said second color space, performing an operation on said sampling slab that causes a color variation in said test pattern, and modify said second master image to compensate said color variation.

4. The method according to claim 3, wherein said operation can comprise firing of the sampling slab in a kiln at a firing temperature substantially equal to the firing temperature of the ceramic slab (1).

5. The method according to claim 3 or 4, wherein the concealed code (50) is applied on the second master image after said modification is performed.

6. The method according to any of the preceding claims, wherein the second color space is a printing color space defined by at least 4 colors or inks, preferably more than 4 colors or inks, for example between 4 and 12 colors or inks.

7. The method according to any of the preceding claims, wherein the second color space differs from a CMYK or RGB color space.

8. The method according to any of the preceding claims, wherein the second color space is defined two or more colors selected from the list comprising, preferably consisting of: cyan, blue, red, brown, pink, yellow, honey, beige, orange, black, purple, green and white.

9. The method according to any of the preceding claims, wherein the second color space is defined by colors in combination with digital material effect inks, wherein digital material effect inks are selected from the list comprising, preferably consisting of: glossy, sinker, structure, matt, metal, luster, glue.

10. The method according to claim any of the preceding claims, wherein said colors or inks defining the color space are selected from the group comprising, preferably consisting of: cyan, blue, red, brown, pink, yellow, honey, beige, orange, black, purple, green, glossy, sinker, structure, matt, metal, luster, glue and white.

11. The method according to any of the preceding claims, wherein applying the concealed code (50) in the master image involves modifying jetting information of one or more of inks defining the second color space.

12. The method according to any of the preceding claims, wherein applying the concealed code in the master image involves modifying jetting information of only one of said color or inks defining the second color space.

13. The method according to any of claims from 9 to 12, wherein applying the concealed code (50) in the master image involves modifying jetting information of one or more digital material effect inks.

14. The method according to any of the preceding claims, wherein the concealed code (50) is continuously repeated over the full decorative pattern.

15. The method according to any of the preceding claims, wherein the concealed code (50) is a steganographic code.

16. The method according to any of the preceding claims, wherein the printed code (50) is composed of a pattern of squares and / or rectangles.

17. The method according to any of the preceding claims, wherein the printed code is composed of a series of clusters of pixels, wherein each pixel in a cluster of pixels has the same color.

18. The method according to any of the preceding claims, wherein the printed code comprises or is composed of missing dots in the decorative pattern.

19. The method according to any of the preceding claims, wherein the concealed code (50) can be read via electronic means, e.g. with an app on a smartphone.

20. The method according to claim 19, wherein reading the concealed code (50) via electronic means, e.g. with an app on a smartphone, returns information on the composition of the ceramic slab comprising the printed decorative pattern.

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