METHOD FOR COLOR CORRECTION OF A DIGITAL PRINT

Description

[0001] The present invention relates to a method for color correction of a digital print and a device for carrying out the method.

[0002] Methods for color correction of digital prints are well known. These involve identifying deviations from the expected print result and incorporating them into the printing process to ensure the print more closely matches the expected result.

[0003] A major challenge in digital image output is achieving prints that exhibit as little deviation as possible from a reference print when printing a digital image repeatedly, even after extended pauses. The reasons for deviations are varied; for example, the printing substrate may exhibit differences in color and gradation properties, or the printer may change over time.

[0004] To quickly correct current color deviations, color correction can be performed on systems based on inkjet printers, for example, by adjusting the printhead voltage. However, this changes the optimal operating point of the printhead and can therefore only be used to a limited extent.

[0005] Another option is to generate new, color-corrected print data using the color management system included with the output device. Depending on the integration of color management into the printing press, the press operator's accessibility to color management, the speed of the color management system, and the total size of the digital image file, this process can take a considerable amount of time.

[0006] Other methods that attempt to avoid resorting to color management include sending correction signals to the print head controller, which implements the correction by adjusting the number and / or size of print dots. One problem with such methods, however, is that special hardware may be required for implementation. Furthermore, due to process reasons, such methods cannot take the correction into account equally in the print feed direction and along the print width. This can lead to disadvantages in the print result. In particular, with such methods, particularly small corrections that are distributed across several print dots due to discrete print dot sizes cannot be distributed evenly in the print feed direction and along the print width, which can cause artifacts.

[0007] Document EP 3 199 347 A2 discloses in this context sending correction signals to the print head controller itself, which implements the correction.

[0008] Color correction methods for digital prints therefore still offer potential for improvement. This potential can be seen in particular in the fact that color correction can be performed more quickly and easily, especially without having to resort to the upstream color management process and / or adjust the printhead voltage.

[0009] This object is achieved by the method for color correction of a digital print according to claim 1 and further by the device according to claim 13. Preferred embodiments of the invention are specified in the subclaims and in the description.

[0010] The invention proposes a method for color correction of a digital print, wherein in a first step a predetermined digital image is provided to a digital printer as a color-separated digital image with at least one color channel image, wherein each color channel image is assigned to a printing ink channel of the digital printer and has information about the printing position and print size of the printing dots to be set by the printer of the corresponding printing ink channel and wherein a printing dot is defined by its printing position and printing dot size, wherein the method further comprises the steps: a) Providing correction data for digital printing, wherein the correction data comprise at least one correction value for at least one color channel image, b) Applying the correction data to the color-separated digital image, whereby a color-corrected color-separated digital image is obtained, c) Printing the color-corrected color-separated digital image with the digital printer, wherein the correction value is applied to the printing dots provided for the color channel image by adjusting the printing dot sizes of at least some of the printing dots of the color channel image depending on the correction value.

[0011] For the purposes of the present invention, digital printing is understood to mean in particular a digital printing process, i.e. a process for printing a digital image with a digital printer.

[0012] For the purposes of the present invention, a digital printer is understood to mean, in particular, a device that can output colored printing dots on a substrate that form the corresponding image.

[0013] For the purposes of the present invention, a digital image is understood in particular to be a digitally storable image whose image information is determined by pixels, each of which has a color value with respect to a color system. A predefined digital image, for the purposes of the present invention, is a digital image intended for printing. For example, the predefined digital image can be a pixel-based or a vector-based digital image.

[0014] The fact that the predetermined digital image is provided to the digital printer as a color-separated digital image with at least one color channel image, wherein each color channel image is assigned to a printing ink channel of the digital printer and has information about printing dots to be set by the printer in the corresponding printing ink channel, and wherein a printing dot is defined by its printing position and printing dot size, is to be understood in the sense of the present invention that the predetermined digital image is provided to the digital printer in particular as a digital image that originates from a RIP process (Raster Image Processor, raster graphics processor), which is therefore already adapted to the printing ink channels of the digital printer and, for example, also to the print resolution of the printer in accordance with the desired printing type. Accordingly, a printing dot in the sense of the present invention can be understood as a dot that is actually to be printed by the printer.

[0015] In the sense of the present invention, a distinction can therefore be made in particular between the predetermined digital image, which is defined via pixels with color values, and the color-separated digital image, whose color channel images are defined via printing points.

[0016] For the purposes of the present invention, a color channel image is understood to mean, in particular, a part of the digital image that contains only the information relating to one color channel of the color system in which the digital image is stored. For example, the digital image can be defined using color values ​​in the CMYK color system, and a color channel image, for example, contains only the color values ​​of the C color channel.

[0017] For the purposes of the present invention, a printing ink channel is understood to mean, in particular, a color channel in which the printer can print. For example, the printer can be designed for printing in the CMYK color system, and a printing ink channel can be the C color channel.

[0018] In other words, it is particularly provided that the digital image is composed of color channel images that correspond to the print color channels of the digital printer. For example, it can be provided that the digital image in the CMYK color system is determined via the color channel images of the C color channel and the M color channel, and the printer is a printer that can print in the CMYK color system. Thus, the print color channels C and M are respectively assigned to the color channel images C and M of the digital image.

[0019] In other words, the specified digital image is provided to the digital printer as a color-separated digital image so that it is directly suitable for printing on the digital printer and contains corresponding information about the printing points to be set in the printing ink channels.

[0020] This can advantageously achieve that the specified digital image can be printed directly and there is no need to resort to the original specified digital image.

[0021] The procedure includes the following steps: a) providing correction data for digital printing, wherein the correction data comprise at least one correction value for at least one color channel image, b) applying the correction data to the color-separated digital image, whereby a color-corrected color-separated digital image is obtained, c) optionally printing the color-corrected color-separated digital image with the digital printer.

[0022] In the context of the present invention, the provision of correction data for digital printing is to be understood as meaning, in particular, the provision of data which is suitable for describing colour deviations from a print of the given digital image to the given digital image.

[0023] For the purposes of the present invention, applying the correction data to the color-separated digital image means, in particular, that the color-separated digital image is modified using the correction data such that the color-corrected, color-separated digital image takes the correction data into account in such a way that the color deviations from the print of the specified digital image are corrected when the color-corrected, color-separated digital image is printed. In other words, this means that the color-separated digital image, which has already been obtained from the specified digital image through a RIP process, is directly subjected to another RIP process using the correction data. In particular, the correction data are not applied to the original, specified digital image.

[0024] In the sense of the present invention, a correction value is understood in particular to be a value that is proportional to a color deviation of a color of an image printed with the digital printer, in particular also as a function of the printing position, to the color of the image used for printing. In other words, a correction value in the sense of the present invention is in particular proportional to a color deviation, whereby the color deviation can be specified as a function of the printing position. In particular, the correction value can have a specific ratio to the color deviation depending on the printer used, a measuring device used to determine the color deviation and / or other equipment used for printing. The ratio of the correction value to the color deviation can preferably be determined by reference measurements.

[0025] The prescribed procedure advantageously makes color correction comparatively faster and easier. In particular, because the correction data is applied to the color-separated digital image, it is possible to avoid the need to resort to the upstream color management process, i.e., in particular, there is no need to resort to the original data of the specified digital image, and furthermore, the print head voltage does not have to be adjusted for the color correction. By not having to resort to the original specified digital image, a significant amount of time can be saved. For example, depending on the computer speed and image size, the procedure can generate completely new, color-corrected, color-separated print files within a few seconds, which can then be printed immediately.The original image files as well as the originally ripped color-separated image files are retained.

[0026] Preferably, it can be provided that the information about the printing points to be set by the printer includes printing positions and printing point sizes of the printing points to be set.

[0027] Preferably, it can be provided that the application of the correction data to the color-separated digital image takes the color-separated digital image into account as a whole. In other words, when applying the correction data, not only a part, section, or the like of the color-separated digital image is used, but the correction data is applied to the color-separated digital image as a whole. In particular, it can preferably be provided that the obtained color-corrected, color-separated digital image is preserved as a whole. For example, it can preferably be provided that the color-corrected, color-separated digital image has the same storage format as the original color-separated digital image.

[0028] The above-described features make it possible, in particular, to apply the method without special control hardware. In particular, the color-corrected, color-separated digital image can be printed exactly as the original color-separated digital image. This makes the method particularly flexible. Furthermore, corrections can be implemented regardless of the printing direction of the specified digital image. Furthermore, even particularly small corrections that must be distributed across multiple printing dots due to discrete printing dot sizes can be distributed evenly in the print feed direction and across the printing width, resulting in a particularly low incidence of artifacts.

[0029] Preferably, it can be provided that, for step c), the color-corrected, color-separated digital image is made available to the digital printer as a whole. In particular, it can be provided that the color-corrected, color-separated digital image is made available to the digital printer in the same way as it would be for a print without correction for the color-separated digital image. This can also result in the aforementioned advantages. In particular, this can ensure that the method can be used particularly flexibly.

[0030] It is also provided that the correction value is applied to the printing points provided for the color channel image by adjusting the printing point sizes of at least some of the printing points of the color channel image depending on the correction value.

[0031] This makes color correction particularly easy to perform.

[0032] For example, it can be provided that the digital image in the CMYK color system is determined via the color channel images of the C color channel and the M color channel and the printer is a printer that can print in the CMYK color system, wherein the provided correction data describes, for example, that the printed image has a C component that is too strong compared to the specified digital image. The correction value then comprises, for example, a negative value for the C color channel, which is applied to the printing dot sizes of the printing dots of the C color channel image by reducing the size of the printing dots of the C color channel. Thus, the color-corrected, color-separated digital image has a lower C component than the color-separated digital image. When the color-corrected, color-separated digital image is printed, the print then has the C component actually intended for printing the specified digital image.

[0033] By applying the correction values ​​directly to the pressure point sizes, the procedure can be carried out particularly easily and quickly.

[0034] Preferably, it can be provided that the correction value is not applied to the pressure point size of pressure points whose pressure point size is 0.

[0035] Pressure points with a pressure point size of 0 are understood to be pressure points for which, according to the color-separated digital image, it is intended that no pressure point at all is set at this point for at least the affected color channel.

[0036] This ensures that the correction values ​​are not applied to areas of the color-separated digital image that have the color value for white. This ensures that the color correction is particularly efficient without creating color artifacts.

[0037] Preferably, it can be provided that the printing dot sizes of the printing dots of the color channel images can assume a limited number of discrete printing dot size values, in particular a number limited by the digital printer.

[0038] A limited number of discrete dot size values ​​means that the dots can only assume a finite number of different dot size values. For example, the digital printer may be designed to print dots with less than or equal to 255 different dot sizes. Digital printers are typically designed to print fewer than 20, and in particular fewer than 10, different dot sizes.

[0039] Preferably, it can be provided that the correction value is applied to the pressure point sizes of the pressure points when applying the correction data in such a way that the pressure point size value of each pressure point is not changed.

[0040] This makes it possible to ensure that even small correction values ​​are taken into account in the color correction, especially correction values ​​that are smaller than the difference between two consecutive print dot size values.

[0041] Preferably, it can be provided that the correction value is applied in such a way that the correction value is distributed over the printing points provided for the color channel image, wherein the distribution of the correction value can preferably be carried out in such a way that the color difference achieved over the sum of the printing points corresponds overall to the correction value.

[0042] This means in particular that when applying the correction data, the correction value is applied to the pressure point sizes of the pressure points in such a way that the resulting pressure point size changes correspond overall to the correction value.

[0043] For example, correction values ​​that would exceed a maximum possible pressure point size when applied to a pressure point can be applied to the pressure point in such a way that it is assigned the maximum possible pressure point size and the remaining correction is achieved by enlarging other pressure points in the vicinity of the pressure point.

[0044] Furthermore, for example, correction values ​​that do not correspond to a discrete pressure point difference between two pressure point sizes can be applied in such a way that, for example, the pressure point size is not adjusted for all pressure points, but rather only for every second, third, fourth, or fifth pressure point. This allows even small correction values ​​to be applied overall.

[0045] In other words, the correction value can be displayed with the changes in the printing point size for the printing points of the color channel image.

[0046] Preferably, it can be provided that the distribution of the correction value to the printing points provided for the color channel image takes place according to the same RIP process on which the given digital image is based.

[0047] This makes it possible to ensure that the distribution of the correction value to the pressure points provided for the color channel image automatically takes into account the positions of the pressure points of the color channel image and / or the limited number of discrete pressure point size values.

[0048] In other words, the number and position of the originally defined pressure points is retained and the pressure point size is increased or decreased for all or only some of the pressure points.

[0049] Preferably, it can be provided that for distributing the correction value to the printing points provided for the color channel image, it is determined successively, in particular according to a predetermined sequence, for each printing point of the color channel image by which printing point size the printing point is to be changed.

[0050] Preferably, it can be provided that when applying the correction value for the respective pressure point position, this position can only assume the same limited number of pressure point size values ​​as the pressure points.

[0051] Preferably, it can be provided that the predetermined sequence occurs according to the same RIP process on which the predetermined digital image is based.

[0052] Preferably, it can be provided that when the correction value determined for the respective printing position is applied one after the other, in the event that the correction value for a specific printing point position reaches a threshold value, the printing point size value of the printing point of the color channel image with the corresponding printing point position is increased or decreased accordingly when the correction data is applied.

[0053] In other words, it can be provided that by applying the correction data to the color-separated digital image, the printing point size of a printing point is only adjusted when distributing the correction value if the corresponding correction value for the printing point position of the corresponding printing point reaches a certain threshold value.

[0054] This makes it possible to ensure that a number of print dot sizes limited by the printing technology are adequately taken into account in the color correction, so that efficient color correction is still possible.

[0055] Preferably, it can be provided that the threshold value corresponds to the color value difference between two consecutive printing dot size values, wherein in the event that the correction value reaches n times the threshold value, the printing dot size value of the printing dots of the color channel image is increased or decreased accordingly by n printing dot size values ​​when applying the correction data, wherein n is a natural number.

[0056] For the purposes of the present invention, successive print point size values ​​are understood to mean the size values ​​of a possible print point size and of the next larger or next smaller print point size.

[0057] This ensures that the color correction is carried out proportionally well even with small and large printing points and is particularly efficient even with small and large correction values.

[0058] Preferably, it can be provided that when the correction value determined for the respective printing position is applied one after the other, in the event that the correction value for a specific printing point position does not reach the threshold value, the printing point size value of the printing point of the color channel image with the corresponding printing point position is not increased or decreased accordingly when the correction data is applied, wherein the correction value is also taken into account for determining the next printing point.

[0059] In other words, it can be provided that, for correction values ​​that are smaller than the smallest pressure point size difference, the correction value is accumulated or distributed to other pressure points when successively determining by which pressure point size a pressure point is to be changed until the threshold value is reached and the pressure point size value of the corresponding pressure point is increased or decreased.

[0060] Preferably, it can be provided that the correction value is distributed to various pressure points that have not yet been corrected using an algorithm, for example using an error distribution algorithm.

[0061] Preferably, it can be provided that when successively determining by which pressure point size a pressure point is to be changed, in the event that the correction value exceeds n times the threshold value, the difference of n times the threshold value and the correction value is taken into account for determining the next pressure point.

[0062] In other words, it can be provided that, in the case of correction values ​​that do not exactly correspond to a possible pressure point size difference, the remaining correction value is accumulated or distributed when successively determining by which pressure point size a pressure point is to be changed until the accumulated remaining correction values ​​reach the threshold value and the pressure point size value of the corresponding pressure point is increased or decreased by n+1 pressure point size values.

[0063] Preferably, it can be provided that in the event that the pressure point size value of a pressure point is to become smaller than the smallest possible pressure point size value when applying the correction data, the pressure point size of the pressure point is set to the pressure point size 0.

[0064] In the context of the present invention, this means that at the corresponding point in the color-corrected, color-separated digital image, it is intended not to set any printing point at all for at least the affected color channel.

[0065] Preferably, it can be provided that in the event that the pressure point size value of a pressure point is to become larger than the largest possible pressure point size value when applying the correction data, the pressure point size of the pressure point is set to the largest possible pressure point size value.

[0066] Preferably, the correction values ​​for the respective printing position are only applied if there is a printing point at this point in the original rasterized image which has a printing point size that is greater than zero.

[0067] Preferably, it can be provided that when changing the print dot size value of the print dots of the color channel image when applying the correction data, an error distribution algorithm is applied (dithering), for example a Floyd-Steinberg algorithm.

[0068] In the context of the present invention, the application of an error distribution algorithm means that the correction values ​​are distributed among adjacent or nearby print dots according to an algorithm such as can also be applied in the RIP process when creating color-separated digital images. In particular, it can be provided that the distribution occurs not only among print dots in the intended print feed direction, but independently in any direction, for example, even perpendicular to the intended print feed direction.

[0069] This can ensure that the color correction has a more uniform effect and artifacts can be avoided.

[0070] In particular, it can preferably be provided that the application of the error distribution algorithm takes place in cases in which the pressure point size value of a pressure point is to become smaller than the smallest possible pressure point size value when applying the correction data and the pressure point size of the pressure point is set to the pressure point size 0 and / or in which the pressure point size value of a pressure point is to become larger than the largest possible pressure point size value when applying the correction data and the pressure point size of the pressure point is set to the largest possible pressure point size value.

[0071] This ensures that color correction is particularly successful even in areas with high and low color density.

[0072] In a preferred embodiment, it can be provided that the application of the correction data to the color-separated digital image takes place at any point of the digital image independently of a color density of the color-separated digital image.

[0073] This makes color correction particularly easy while still achieving good results.

[0074] In an alternative preferred embodiment, it can be provided that the correction data is applied to the color-separated digital image depending on a density map generated from at least one color channel image, wherein the density map comprises information about a color density of the color channel image as a function of the printing position. The term "color density" in the context of the present invention can be understood in particular as a color saturation. In other words, it can be provided that a color channel image is processed in such a way that a color saturation is obtained as a function of the printing position.

[0075] This allows for further improvement in color correction. In particular, color correction can be performed with greater precision, even in areas with very different color densities.

[0076] Preferably, it can be provided that the density map was created from the color channel image of the color-separated digital image, wherein the color density is preferably obtained with a blur as a function of the printing position of the color channel image.

[0077] This makes it possible to obtain the density map particularly quickly and easily, especially without resorting to the upstream color management process and the original specified digital image.

[0078] Preferably, it can be provided that the correction data are applied to the color channel image of the color-separated digital image as a function of a gradation curve.

[0079] In the context of the present invention, a gradation curve is understood to mean a curve that describes the relationship between at least two color densities and is understood here to mean that a factor is described as a function of the color density that can be applied to the correction value.

[0080] Thus, a gradation curve can be used for color correction, which sets the strength of the correction depending on the color density. For example, the gradation curve can stipulate that areas with lower color density are corrected proportionally less than areas with higher color density, or vice versa.

[0081] This makes it possible to adjust the finer details of the color correction particularly quickly and easily.

[0082] Preferably, it can be provided that the correction value depends on the print width of the digital printer.

[0083] This advantageously makes it possible to correct errors that occur, in particular, due to fluctuations in the print head of the digital printer along the print width, i.e. transversely to a print feed direction.

[0084] Preferably, it can be provided that the provision of the correction data for digital printing in step a) comprises printing the color-separated digital image and / or a digital test image with the digital printer and detecting color values ​​of the printed color-separated digital image and / or digital test image with an optical color measuring device, wherein the correction values ​​are created based on deviations of the color value measured for a printing position from the color value expected for the specified digital image and / or the digital test image at this printing position.

[0085] A digital test image is a predefined digital image that is designed in such a way that correction data can be obtained particularly efficiently from the print of the test image.

[0086] By capturing the color values ​​as described above, the correction data can be made particularly reliable.

[0087] In particular, it can be provided that printing takes place on the same substrate on which the specified digital image is to be printed.

[0088] This has the advantage that substrate effects can also be easily taken into account during color correction.

[0089] Preferably, steps a) and b) can be performed iteratively several times in succession. In particular, the provision of the correction data in a step a) following step b) can include printing the color-corrected, color-separated digital image, with the correction data being applied to the already color-corrected, color-separated digital image in the subsequent step b), resulting in a further color-corrected, color-separated digital image.

[0090] This ensures that the color correction achieves a particularly homogeneous print result.

[0091] Particularly preferably, steps a) and b) can be performed iteratively until the correction result is sufficiently good. In particular, steps a) and b) can be performed until the correction values ​​provided in step a) are sufficiently small.

[0092] Optionally, the success of the process can be checked by printing the specified digital image with the appropriate correction data applied.

[0093] Preferably, it can be provided that the optical color measuring device is selected from the group consisting of a color sensor, a colorimeter, a spectrophotometer, a digital camera or a spectrodensitometer, wherein the optical color measuring device is preferably based on the same color model as the digital printer.

[0094] Preferably, it can be provided that the color values ​​are optionally recorded several times in succession with different settings of the optical color measuring device, in particular under different lighting conditions and / or exposure times.

[0095] This makes it possible to detect even very small color deviations.

[0096] Preferably, it can be provided that the predetermined digital image has a color model selected from RGB, CMY and CMYK, wherein the color model is in particular CMYK.

[0097] Preferably, it can be provided that the method comprises creating the information about the printing points to be set by the printer, wherein step b) takes place when creating the information about the printing points to be set by the printer, in particular each time after a printing point has been created.

[0098] This means that during the RIP process of the given digital image, the correction data are applied according to the invention, whereby the correction data are not taken into account before a printing point is created but are only applied to a printing point once it has been created, as described above.

[0099] This makes it possible to achieve the same correction results directly when creating the digital image to be printed as with a correction after the RIP process.

[0100] Preferably, it can be provided that printing the color-corrected, color-separated digital image with the digital printer comprises printing decorations, in particular printing decorations for decorative panels.

[0101] The invention further proposes a device comprising a data memory, a computing unit, a digital printer for outputting a predetermined digital image and optionally an optical color measuring device, wherein the device is configured to carry out the method described above.

[0102] Furthermore, a use of the above-described method or the above-described device for color correction for the printing of decorations is proposed, in particular for the printing of decorations for decorative panels.

[0103] Surprisingly, it was shown that the above-described method is particularly well suited for color correction in such applications. Especially when printing decorative panels, it is important to ensure that the color does not vary between different batches, as these can also be laid side by side, making color deviations particularly noticeable. Furthermore, such applications require high throughput, so particularly fast color correction, as achievable with the present invention, is particularly advantageous.

Claims

1. A method for color correcting a digital print, wherein, in a first step, a specified digital image is provided to a digital printer as a color-separate digital image with at least one color channel pattern, wherein each color channel pattern is associated with a print color channel of the digital printer and has information relating to the printing position and printing size of the printing points to be placed by the printer of the corresponding print color channel, and a printing point is defined by the printing position and size thereof, wherein the method additionally comprises the steps of: a) providing correction data for the digital print, wherein the correction data at least comprises a correction value for at least one color channel pattern, b) using the correction data on the color-separate digital image, wherein a color-corrected color-separate digital image is obtained, c) printing the color-corrected color-separate digital image using the digital printer, wherein the correction value is used on the printing points intended for the color channel pattern by adjusting the printing point sizes of at least a part of the printing points of the color channel pattern depending on the correction value.

2. The method according to claim 1, wherein the correction value is not used on the size of printing points, whose size is 0.

3. The method according to any of claims 1 or 2, wherein the sizes of the printing points of the color channel patterns can assume a limited number of discrete printing point size values, in particular a number limited by the digital printer.

4. The method according to any of claims 1 to 3, wherein the correction value is used in such a way that the correction value is distributed over the printing points intended for the color channel pattern, wherein the distribution of the correction value is performed such that the color difference achieved over all of the printing points in total corresponds to the correction value.

5. The method according to any of claims 3 or 4, wherein, in the case that the printing point size value of a printing point should become smaller than the smallest possible printing point size value when using the correction data, the size of the printing point is set to 0.

6. The method according to any of claims 3 to 5, wherein, in the case that the printing point size value of a printing point should become larger than the largest possible printing point size value when using the correction data, the size of the printing point is set to the largest possible printing point size value.

7. The method according to any of claims 3 to 6, wherein, when changing the printing point size value of the printing points of the color channel pattern while using the correction data, an error distribution algorithm (dithering) is used, for example a Floyd-Steinberg algorithm.

8. The method according to any of claims 1 to 7, wherein the use of the correction data on the color-separate digital image is performed depending on a density map generated from at least one color channel pattern, wherein the density map includes information relating to the color density of the color channel pattern depending on the printing position.

9. The method according to claim 8, wherein the density map was created from the color channel pattern of the color-separate digital image, wherein the color density depending on the printing position of the color channel pattern is preferably obtained using a blurring tool.

10. Method according to any of claims 8 or 9, wherein the correction data is used on the color channel pattern of the color-separate digital image depending on a gradation curve.

11. The method according to any of claims 1 to 10, wherein the correction value depends on the printing width of the digital printer.

12. The method according to any of claims 1 to 11, wherein providing the correction data for the digital print in step a) includes printing the color-separate digital image and / or a digital test image using the digital printer and acquiring color values of the printed color-separate digital image and / or digital test image using an optical color measuring apparatus, wherein the correction values are created based on deviations of the color value measured for a printing position from the color value expected for the specified digital image and / or the digital test image at this printing position.

13. A device comprising a data storage, a computing unit, a digital printer for outputting a specified digital image, and optionally an optical color measuring apparatus, wherein the device is configured to perform the method according to any of claims 1 to 12.