System and method for obtaining a uniform ink layer

Abstract

A method for creating a bitmap for a printing plate comprises: defining an area of ​​an image to be printed with a solid color; applying a halftone screen to the defined solid color area; and creating a bitmap of the halftone screen embodied in the defined solid color area. The halftone screen pattern comprises a plurality of dashes having a positive or negative 45-degree orientation, a positive or negative 135-degree orientation, or a combination of two or more positive or negative 45-degree and 135-degree orientations. Each dash or its constituent dashes have two or more adjacent contact pixels of the same length and a certain number of one or more adjacent contact pixels of the same width, or the dashes are arranged orthogonally in rows and columns, or a combination thereof. Masks, printing plates, processes for making them, and printing methods using the bitmap are also described.

Description

Background Art

[0001] In flexographic printing, it is often necessary to ink the substrate with a background ink (e.g., white), such as when inking a transparent substrate or a substrate with a non-neutral color. Important criteria for the background ink layer are its hiding quality and its color uniformity. Relatively good hiding quality results in a relatively small amount of light passing through the background ink layer. Relatively good uniformity allows for relatively accurate color reproduction of the artwork printed on top of the background. Maximizing hiding quality and uniformity can be hampered by specific characteristics of the ink (e.g., low-pigmentation inks) and / or the substrate (e.g., ink-repellent substrates), which result in incomplete or uneven ink transfer.

[0002] Basic methods for increasing the hiding power of the background ink layer include using a large amount of background ink (e.g., by using a large volume anilox roller to ink the printing plate) and / or printing multiple layers of background ink. These methods are inefficient and costly because they consume a large amount of ink and / or require more press time to perform multiple print runs.

[0003] A more economical approach is to improve the ink transfer properties of the ink-bearing raised surface of a flexible relief plate. One way to improve ink transfer properties is by adding "roughness" to the ink-bearing plate surface. Some methods for roughening the surface include applying special coatings or treatments during the manufacture of flexographic polymer plates. The disadvantage of this approach is that the roughness is not fully controllable and is not flexible. Experiments have shown that the optimal roughness comprises an ordered surface pattern with a frequency and shape that matches the inking system (e.g., matching the anilox roller unit properties and frequency). Since the plate roughness is built into the plate by the aforementioned methods, it cannot be optimally matched to the anilox roller properties.

[0004] Another more controlled and flexible method is to apply surface roughness digitally, such as by creating a specific repeating pattern in a digital bitmap file, imaging the bitmap onto a photosensitive mask mounted on top of a polymer plate, and exposing the pattern through the mask onto the polymer plate, such as with UV light. A halftone screen, which is a basic repeating digital pattern similar to those commonly used to represent tones, is one such pattern. To match the anilox roll grid and cell size, a specific halftone dot shape, screen ruling, and grayscale can be selected that more or less matches the anilox roll's properties. Certain specialized and more advanced patterns are known that further improve ink transfer by better matching the anilox roll grid and cell properties, such as, for example, as described in patents and applications from Mark Samworth (e.g., U.S. Patent No. 6,121,301 entitled FLEXOGRAPHIC PRINTING PLATE HAVING IMPROVED SOLIDS RENDITION and patents related thereto or referenced thereto) and from Hans DeWitte (e.g., European Patent No. EP1557279 and patents related thereto or referenced thereto), which are incorporated herein by reference.

[0005] However, one drawback of these digital methods is that the frequency, shape, and size of the pattern are limited by the platemaking properties of the system in which they are used. For example, depending on the type of mask, the pattern may not always be perfectly imaged through the mask (due to thickness and the energy required to perforate the mask). Furthermore, oxygen effects during UV exposure can lead to less-than-accurate reproduction of the pattern on the surface of the polymer plate. Historically, the exposure step has been performed using UV bulbs that do not distribute the UV light energy evenly and uniformly across the entire plate surface. As a result, very small or high-frequency digital surface patterns are not well formed on the surface of the flexographic plate. Moreover, the surface patterns thus created are often unstable over time or are not uniform across the entire surface of the plate.

[0006] Fortunately, recent developments in platemaking technology allow for more precise structures to be applied to flexographic surfaces. One of these developments is a special method for imaging and perforating digital images on a photosensitive mask or laser ablation mask (LAM). According to this method, the pattern in the digital file is defined by a series of set and cleared pixels. A specific sub-pattern of set pixels (2×2 checkerboard) is detected by an imaging system and triggers a high-energy laser pulse. This high-energy laser pulse results in a sharp perforation through the mask. The number of high laser energy pulses is controllable in such a way that the surface pattern formed on the finished printing plate has the appropriate relief and size. A commercial version of the above technology is called ESKO Pixel Boost™ technology. Exemplary methods and systems are discussed in U.S. published application serial number US20190315141A1 ('141 publication) entitled METHOD FOR SMOOTHER TONAL RESPONSE IN FLEXOGRAPHICPRINTING, which is incorporated herein by reference.

[0007] Another development comes from improvements to UV exposure technology. Instead of using UV light bulbs, exposure using UV light-emitting diodes (LEDs) allows for more controlled, uniform, and precise UV exposure of the polymer layer at the mask opening. In addition, the front and back UV exposures can be performed simultaneously, or in a deliberate order, thereby delivering a more accurate and stable relief depth and minimizing oxygen problems. Such improvements in technology are discussed, for example, in U.S. published patent application number US2018 / 0210345A1, entitled PROCESS AND APPARATUS FOR CONTROLLED EXPOSURE OF FLEXOGRAPHIC PRINTING PLATES AND ADJUSTING THE FLOORTHEREOF, and the patents referenced therein, which are incorporated herein by reference.

[0008] With these new developments, finer and higher-frequency surface patterns are now possible on the ink-bearing surfaces of flexographic plates. These higher-frequency patterns allow the use of inking systems with a smaller grid of ink-bearing cells. Consequently, a more uniform printed background ink layer can be achieved using less ink. However, some patterns perform better than others, and there is a need in the art to identify the optimal patterns. Summary of the Invention

[0009] One aspect of the present invention includes a method for creating a bitmap for creating a printing plate for printing ink on a substrate. The method includes: defining an area of ​​an image intended to be printed with ink; applying a halftone screen to the defined area; and creating a bitmap that embodies the application of the halftone screen to the defined area. The defined area can be an area intended to be printed in a solid color reproduction area or printed with halftones. The halftone screen includes a pattern comprising a plurality of dashes having a positive or negative 45 degree orientation, a positive or negative 135 degree orientation, or a combination of two or more positive or negative 45 degree and 135 degree orientations, wherein (i) each dash or its component dashes includes two or more adjacent contact pixels of the same number (M) in length and one or more adjacent contact pixels of the same number (T) in width, (ii) the dashes are arranged orthogonally in rows and columns; or (iii) a combination of (i) and (ii).

[0010] In some embodiments, M is in the range of 2 to 4, and T is in the range of 1 to 3. In some embodiments, each dash comprises: the same number T of pixels in width, where T is an odd number greater than 1; and T constituent single-pixel dashes, where at least one single-pixel dash comprises M+1 adjacent touching pixels in length.

[0011] In one embodiment, the halftone pattern includes alternating columns of dashed lines having a positive or negative 45 degree orientation and columns of dashed lines having a positive or negative 135 degree orientation. In this embodiment, the topmost pixel of a dashed line may have a 45 degree orientation aligned with the bottommost pixel of a dashed line having a 135 degree orientation.

[0012] Embodiments include those in which dashes of M pixels are grouped diagonally, with N pixels between adjacent dashes in the same diagonal, and wherein the dashes are offset from each other by a value of V vertical pixels. In some embodiments, M is in the range of 2 to 4, N is in the range of 2 to 4, and V is in the range of 4 to 8. In a preferred embodiment, M=4, N=2, and V=6.

[0013] Another aspect of the invention includes a computer storage medium product embodying non-transitory machine-readable instructions corresponding to a bitmap produced by any of the methods as disclosed herein.

[0014] Yet another aspect of the present invention includes a process for creating a mask, and a mask created thereby, for creating a printing plate for printing ink on a substrate, the method comprising: providing a bitmap created by any of the methods described herein, and applying the bitmap to the mask by forming a pattern of holes in the mask corresponding to the bitmap. In such a process, where T=1, the step of forming the holes may comprise ablating a portion of the mask with a laser, wherein the laser is applied to features in the bitmap that define a 2×2 checkerboard pattern at a first laser power, and the laser is applied to features in the bitmap that do not define a 2×2 checkerboard pattern at a second laser power, wherein the first power is greater than the second power. In such a process, where T>1, the step of forming the holes may comprise ablating a portion of the mask with a laser, wherein the laser is applied at the same laser power to create each feature defined in the bitmap.

[0015] Another aspect of the invention includes a process for creating a printing plate for printing ink on a substrate, and a printing plate created thereby, the process comprising: providing a printing plate having a mask created by any of the processes described herein; exposing the printing plate to actinic radiation through apertures in the mask, thereby curing the portions of the printing plate that received the actinic radiation; and processing the printing plate to remove uncured areas of the printing plate, thereby creating raised areas in the printing plate, the raised areas corresponding to the halftone screen in portions of the printing plate corresponding to defined areas of the image.

[0016] Another aspect of the present invention includes a method of printing, comprising: providing a printing plate produced by any of the processes described herein, applying a first ink to the printing plate; and transferring the first ink to a substrate as a first ink layer in areas of the substrate corresponding to defined areas of an image. The ink transferred to the substrate in the areas corresponding to the defined areas can be a background color, wherein the method further comprises printing over the first ink layer with at least a second ink. The method can include printing on a transparent or translucent substrate and can particularly include printing with a white ink.

[0017] Another aspect of the present invention includes a system for creating a printing plate, the system comprising a computer processor and digital memory accessible to the computer processor, the digital memory embodying non-transitory machine-readable instructions for performing any of the methods for creating a bitmap as described herein. An imager controllable by the processor is configured to apply the bitmap to a mask by forming a pattern of holes in the mask corresponding to the bitmap. An exposure unit (optionally controlled by the processor) is configured to expose the photopolymer printing plate to actinic radiation through the mask. One or more post-exposure units (such as a washing unit) are configured to remove uncured photopolymer from the printing plate. The imager may include a laser for forming the holes in the mask, in which case the system is configured to apply a first, relatively large laser power to features in the bitmap that define a 2×2 checkerboard pattern and a second, relatively small laser power to features in the bitmap that do not define a 2×2 checkerboard pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1A Depicts a bitmap of an exemplary surface screen having an exemplary 4-pixel-on-one-pixel dash pattern with a 45-degree orientation, referred to herein as "EXP3."

[0019] Figure 1B A bitmap depicting an exemplary surface screen having an "EXP3" pattern oriented at 135 degrees.

[0020] Figure 1C A first exemplary 2x2 checkerboard pattern is depicted.

[0021] Figure 1D A second exemplary 2x2 checkerboard pattern is depicted.

[0022] Figure 2A Microscopic image capture depicting a transparent substrate printed with white ink and placed on a black background reference paper, wherein the printing was performed with a standard printing plate produced without applying a surface screen as described herein.

[0023] As if targeting Figure 2A , Figure 2B Microscopic image capture depicting a similar transparent substrate printed with a similar white ink and placed on a similar black background reference paper, but where the printing was performed with a printing plate created by applying the EXP3 surface screen as described herein.

[0024] Figure 3A Magnified microscopic image capture depicting a transparent substrate printed with white ink and placed on a black background reference paper, wherein the printing was performed with a printing plate created by applying a surface screen comprising a linear pattern 3 pixels thick.

[0025] Figure 3BDepicting magnified microscopic image capture of a transparent substrate printed with white ink and placed on a black background reference paper, all similar to Figure 3A The case where printing is performed by applying Figure 3C This is done by creating a printing plate using a 2-pixel linear pattern depicted in [1].

[0026] Figure 3C Depicts a bitmap of an exemplary surface screen comprising a 2 pixel linear pattern at 943 lpi.

[0027] Figure 4A Depicts a bitmap of an exemplary surface screen comprising a combination of interlaced 4-pixel-on, 2-pixel-off single-pixel dashes at 45 and 135 degree orientations.

[0028] Figure 4B Depicts a bitmap of an exemplary surface screen comprising a combination of interlaced 4 pixel on, 4 pixel off single pixel dashes at 45 and 135 degree orientations.

[0029] Figure 4C Depicts a bitmap of an exemplary surface screen comprising a combination of interlaced 2 pixel on 2 pixel off single pixel dashes at 45 and 135 degree orientations.

[0030] Figure 4D Depicts a bitmap of an exemplary surface screen comprising a combination of interlaced 3 pixel on 3 pixel off single pixel dashes at 45 and 135 degree orientations.

[0031] Figure 4E A bitmap depicting an exemplary surface screen comprising a combination of single-pixel dashes 3 pixels apart at 45 and 135 degree orientations, where dashes of the same orientation are stacked in columns with a 4 pixel offset, where the top-most pixel in alternating columns of different orientations is aligned with the bottom-most pixel of the dash of the opposite orientation.

[0032] Figure 5A Describing the embodiment Figure 4A A magnified microscopic image of the surface of a silk screen printing plate is captured, where the lighter areas represent raised ink-bearing areas, while the darker areas represent non-ink-bearing areas.

[0033] Figure 5B Describing the embodiment Figure 4C A magnified microscopic image of the surface of the screen printing plate is captured.

[0034] Figure 6A Describing the embodiment Figure 4D A magnified microscopic image of the surface of a screen printing plate is captured, where the features on the mask used to create the printing plate are plotted against the Figure 6B The plate depicted in FIG is imaged using relatively small pulse energies.

[0035] Figure 6B Describing the embodiment Figure 4D A magnified microscopic image of the surface of a screen printing plate is captured, where the features on the mask used to create the printing plate are plotted against the Figure 6A The plate depicted in FIG was imaged with a relatively larger pulse energy.

[0036] Figures 7A-7E Depicted are the corresponding surface patterns applied in the experiments used to compile the data in Tables 1-6.

[0037] Figure 8A Depicting a plan view of an exemplary portion of a digital file having a dashed line pattern.

[0038] Figure 8B Describe from Figure 8A Plan view of an exemplary portion of the mask created from the digital file.

[0039] Figure 8C Describe from Figure 8B Cross-sectional view of a portion of an exemplary printing plate created with a mask.

[0040] Figure 8D depiction Figure 8C A cross-sectional view of a portion of an exemplary printing plate that carries ink for transfer to a substrate.

[0041] Figure 9A A bitmap depicting an exemplary surface screen comprising a dashed line pattern comprising lines 2 pixels thick.

[0042] Figure 9B A bitmap depicting an exemplary surface screen comprising a dash pattern comprising 3 pixel thick lines formed from adjacent 4 pixel long, 1 pixel thick constituent dashes.

[0043] Figure 9C depiction Figure 9B A mirror image of a bitmap flipped across the vertical axis.

[0044] Figure 9D depiction Figure 9B A mirror image of a bitmap flipped across the horizontal axis.

[0045] Figure 9E depiction Figure 9B A 180-degree rotation of the bitmap.

[0046] Figure 9F A bitmap depicting an exemplary surface screen comprising another 3 pixel dash pattern formed from adjacent single pixel thick constituent dashes having lengths of 4, 5, and 4 pixels, respectively.

[0047] Figure 10 A bitmap depicting an example halftone area to which the EXP3 surface pattern has been applied.

[0048] Figure 11 is a diagram of an exemplary system according to an aspect of the present invention. DETAILED DESCRIPTION

[0049] Aspects of the present invention include systems and methods for achieving a uniform ink layer, such as for use as a background color in flexographic surface printing. A specific fine 3D structure extending to the raised surface of a flexographic relief plate imparts roughness to the ink-bearing surface of the printing plate, thereby providing better ink transfer from the inking system to the substrate, resulting in a more uniform printed ink layer without uninked spots or pinholes.

[0050] One embodiment includes applying a surface screen to a solid ink area, wherein the surface screen includes a specialized pattern consisting of a repetition of dashes at a 45 or 135 degree orientation, such as at Figure 1A The patterns depicted in Figure 1B As used herein, "45-degree orientation" and "135-degree orientation" refer to the angle formed between a line drawn through the "on" pixels and an axis extending horizontally to the right. It is worth noting that a screen with a 45-degree orientation is a mirror image of the same pattern at a 135-degree angle, and vice versa.

[0051] Figure 1A and 1B Depicts digital files (bitmaps) corresponding to exemplary surface screens as described herein. These surface screens are applied to solid color reproduction areas (areas intended for printing solid colors). Reference is now made to Figure 8A In the context of "surface screen printing" as discussed herein, each black pixel line segment 802 in the digital file 800 results in a microscopic line segment opening 812 in the mask 810 after imaging. These small openings cause the line segments on the printing plate to solidify, leaving small, thin microscopic gaps or "engravings" 824 between the imaged line segment features 822 on the ink-bearing surface area of ​​the printing plate 820 after the uncured portions have been washed away. The close spacing and high resolution of the imaged line segment features means that these gaps between the imaged features do not extend to the plate floor 826, but rather are relative to the raised areas of the plate floor, but at a slightly smaller height than the imaged features. These microscopic engravings 824 allow the ink 828 to adhere much better and more evenly across the raised areas of the printing plate, thereby facilitating a more uniform ink coating transfer to the substrate 830 to which the ink is applied.

[0052] Pattern 100 includes single-pixel dashed lines oriented at a 45-degree angle with four (4) pixels on and two (2) pixels off (this can also be expressed as a 4-pixel dashed line with a horizontal offset H of six (6) pixels between corresponding pixels of horizontally adjacent dashed lines), with adjacent lines (and adjacent vertical dashed lines) having a vertical offset V of six (6) pixels. The six (6) pixel "offset" results in a gap of five (5) "off" pixels between similarly positioned "on" pixels. Pattern 110 includes single-pixel dashed lines oriented at a 135-degree angle with four (4) pixels on and two (2) pixels off, with adjacent lines offset by six (6) pixels. These patterns are referred to herein as "EXP3" patterns. Another way to think of this pattern is that it comprises a series of continuous diagonal lines 102, such as the grooves described in EP1557279, with 2 pixel thick strokes 104 applied in the vertical and horizontal directions closing any on pixels, breaking the continuous lines into dashes.

[0053] For a dash with a thickness of one pixel, an exemplary process includes using Figure 1C A special imaging mode of laser enhancement (i.e., using Esko PixelBoost™ technology, sometimes referred to herein as "P+") is triggered at the locations of the 2×2 pixel checkerboard pattern depicted in Figure 1 or 1D to image the digital pattern onto a photosensitive mask (LAM) on top of the flexographic plate. For dashes having a thickness of two or more pixels, the process involves imaging the digital pattern onto the mask using a standard (non-enhanced) imaging mode. The photopolymer plate is then exposed through the mask using a UV LED exposure system to cure (e.g., cross-link) the photopolymer in the exposed areas. The mask and uncured polymer structure are washed off, leaving the desired roughness pattern on top of the relief.

[0054] The patterns created by the aforementioned imaging and exposure steps are used to evaluate the effect of different surface patterns on the hiding power of white ink. Two metrics are used to evaluate hiding power: print opacity and noisiness. The print opacity metric indicates how much background light is blocked by the printed ink layer and can be measured with a spectrophotometer or densitometer. The noisiness metric is a measure of the uniformity of the ink layer and is measured by digitally scanning the ink layer and processing the scanned data with a digital processor. For example, readings taken with a Flex3Pro plate analyzer and processed using Fleye software (both from Peret GmbH) can provide repeatable measurements using a noisiness function. Opacity is another useful metric for distinguishing and comparing the effectiveness of different types of surface screen printing.

[0055] Although print opacity is commonly used as a measure of the hiding quality of an ink layer, research has shown that this measure does not fully represent the hiding power of the background ink. Figure 2A and 2B Depicted images, Figure 2A and 2B Both are microscopic image captures of substrates printed with white ink and placed on a black background reference paper. Figure 2A Corresponds to an ink layer laid down by a solid color printing plate surface without applying a surface screen (such as one of the screens as discussed herein) to the solid color ink areas. Figure 2B Corresponds to a plate surface having the surface screen printed, using the EXP3 pattern as described herein, imaged with P+ imaging and exposed using Esko XPS™ technology (LED UV). Figure 2A In the example, many black spots from the black background paper are visible through the white ink layer, and the white inked areas surrounding the black pinholes have different color densities. Figure 2B In the , relatively few black spots are visible, and the white ink color is more uniform. However, Figure 2A The measured print opacity is higher than Figure 2B On the other hand, Figure 2B The noise measurement ratio Figure 2A Much lower. Figure 2B The ink coverage shown in is preferred because the background color is uniform and will have less interference with the multi-colored artwork printed on it.

[0056] The results further showed that using a very fine line structure significantly reduced noise. Figure 3A and 3B Shown are microscopic captures of white ink printed using two different line patterns. Figure 3A Printing was performed using a repetition of lines at 943 LPI, each line having a thickness of 3 pixels. Figure 3B Use the same repetition but with a line that is 2 pixels thick (such as Figure 3C The screen is depicted in FIG) for printing. Figure 3B The capture shown in FIG, printed with finer lines, clearly shows less noise and pinholes.

[0057] Further investigation also revealed that the best results were obtained when the frequency of the line pattern matched the frequency of the anilox roll elements. Tables 1-6 provide an overview of the color noise measurements obtained from patches using different surface structures and frequencies. The surface structures on the plates were all obtained using P+ imaging and ESKO XPS UV LED exposure. The patches were all taken at a constant speed (300 M / min (meters per minute)) using different plate types (MacDermid ITP, Asahi AFP-TOP, DuPont TM Cyrel® DPR) and different anilox roller L / cm properties, printed with different white ink types (NC = nitrocellulose ink, PU = polyurethane ink). The rightmost column in the table labeled "solid color" is the noise value from the patch without surface pattern. The remaining columns refer to the pattern as depicted in the figure. For example, in Figure 7A The MCWSI pattern is depicted in Figure 7B The MG34 pattern is depicted in Figure 7C The MG56 pattern is depicted in FIG. The columns labeled 471 to 942 refer to the frequencies of line patterns (e.g., from 471 LPI to 942 LPI) such as Figure 7D The pattern corresponding to 808 LPI and Figure 7E The pattern depicted in corresponds to 942 LPI. The rows labeled 100 to 180 indicate the anilox roll unit frequencies from 100 LPI to 180 LPI. The lowest noise value corresponds to the most uniform ink layer.

[0058] These tables show that patterns with higher line frequencies perform better when used with higher anilox roll unit frequencies. Figure 1A The performance of the pattern shown in ) surprisingly exceeds the other patterns because the noise values ​​are very low for the entire range of anilox roll unit frequencies. Therefore, this pattern shows less dependence on anilox roll unit frequency than the other patterns, making it particularly useful.

[0059] Using the EXP3 pattern, print opacity can be adjusted independently of noise, meaning that changing the inking type or amount (changing the anilox roll grid and cell size) allows the user to adjust opacity or color without adding noise or introducing needle perforations.

[0060] Table 1: Printing plate: MacDermid ITP; ink: NC

[0061] Anilox roller L / cm MCWSI MG34 MG56 EXP3 471 512 565 628 707 808 942 Solid color 100 2.03 2.61 2.45 0.12 4.91 2.38 0.07 0.07 0.21 0.62 0.12 2.67 120 3.91 4.92 2.69 0.12 1.80 0.19 0.13 0.09 1.58 4.49 140 6.11 8.78 3.00 0.38 3.21 0.69 0.06 0.09 0.78 5.66 160 5.77 7.65 3.17 0.26 0.42 0.20 0.19 6.03 180 2.05 9.66 2.49 0.18 4.90 0.98 0.85 7.40

[0062] Table 2: Printing plate: MacDermid ITP; ink: PU

[0063] Anilox roller L / cm MCWSI MG34 MG56 EXP3 471 512 565 628 707 808 942 Solid color 100 0.28 0.27 2.36 0.18 7.86 7.14 0.24 0.06 0.05 0.28 0.25 1.35 120 6.21 5.20 2.84 0.09 2.70 0.05 0.04 0.06 0.34 2.07 140 4.26 5.24 3.90 0.37 3.12 1.48 0.15 0.11 0.74 4.64 160 8.80 7.70 3.93 0.09 0.25 0.07 0.57 3.04 180 1.85 5.59 2.26 0.06 1.26 0.28 0.25 3.42

[0064] Table 3: Printing plate: Asahi AFP-TOP; Ink: NC

[0065] Anilox roller L / cm MCWSI MG34 MG56 EXP3 471 512 565 628 707 808 942 Solid color 100 6.53 4.71 4.83 0.97 8.92 7.26 0.74 0.10 0.06 0.77 2.13 6.88 120 7.86 12.40 4.16 1.32 0.60 0.18 0.05 1.12 1.79 7.02 140 11.83 15.15 8.89 0.56 4.77 3.83 0.11 0.13 2.81 8.22 160 10.73 9.26 11.19 1.06 2.73 1.01 0.55 6.39 180 3.92 9.47 4.62 0.36 13.33 6.58 0.98 9.26

[0066] Table 4: Printing plate: Asahi AFP-TOP; Ink: PU

[0067] Anilox roller L / cm MCWSI MG34 MG56 EXP3 471 512 565 628 707 808 942 Solid color 100 0.81 1.82 0.06 0.03 0.68 0.22 0.02 0.03 0.04 0.05 0.07 0.78 120 0.99 3.28 0.22 0.03 0.07 0.11 0.04 0.03 0.03 1.32 140 1.11 2.24 0.18 0.10 1.01 0.44 0.04 0.03 0.02 3.08 160 0.51 2.19 0.20 0.14 0.24 0.16 0.03 2.34 180 0.55 1.47 0.06 0.06 0.29 0.10 0.04 3.12

[0068] Table 5: Printing plate: DuPont TM Cyrel® DPR; Ink: NC

[0069] Anilox roller L / cm MCWSI MG34 MG56 EXP3 471 512 565 628 707 808 942 Solid color 100 0.40 0.13 0.03 0.02 0.41 0.27 0.02 0.02 0.07 0.02 0.01 0.07 120 0.40 1.62 0.03 0.04 0.03 0.04 0.01 0.03 0.07 0.73 140 1.43 1.93 0.04 0.05 0.06 0.03 0.03 0.04 0.04 1.39 160 0.89 2.30 0.05 0.05 0.05 0.03 0.03 0.97 180 0.30 1.09 0.06 0.09 0.05 0.05 0.03 0.45

[0070] Table 6: Printing Plate: DuPont TM Cyrel® DPR; Ink: PU

[0071] Anilox roller L / cm MCWSI MG34 MG56 EXP3 471 512 565 628 707 808 942 Solid color 100 0.26 0.44 0.10 0.03 0.53 0.13 0.01 0.03 0.02 0.01 0.02 0.05 120 1.18 1.12 0.12 0.01 0.03 0.02 0.02 0.02 0.02 0.34 140 0.71 2.60 0.47 0.03 0.10 0.04 0.04 0.03 0.07 0.44 160 0.50 2.32 0.26 0.03 0.06 0.05 0.02 0.98 180 0.16 1.34 0.23 0.05 0.07 0.06 0.03 0.84

[0072] In use, a digital artwork design (e.g., a PDF file) is first created that identifies one or more solid color areas to be printed with a specific background ink. In a raster image processor (RIP), the design is separated into different two-layer bitmaps. Each separation is intended to be used to image a flexographic plate for printing a specific process color. The separations generated by the RIP for the background ink include the identified solid color areas that are colored with the desired specific digital pattern.

[0073] Exemplary patterns

[0074] Preferred digital patterns are constructed from groups of connected pixels that form multi-pixel line segments (i.e., "dashes") at a 45-degree orientation, a 135-degree orientation, or a combination thereof. Each group of connected pixels can include a series of single pixels, and in some embodiments, the multi-pixel line segments can be aligned to form dashes with a constant repetition between adjacent dashes in the same line and another constant repetition between dashes.

[0075] When using lines with a single pixel thickness, the ESKO CDI Power Boost (P+) technology is able to detect the 2×2 pixel checkerboard pattern inherent in each line. At each position in the dual-layer bitmap that constructs the 2×2 checkerboard, the Laser CDI P+ system triggers a high-energy laser pulse on the LAM layer of the flexographic plate, causing the LAM layer to ablate at that specific position, resulting in a transparent spot at that position. Figure 1A and 1BThe digital pattern depicted in includes multiple such 2×2 pixel checkerboard patterns, so when the dual-layer bitmap used by the CDIP+ technology contains such areas with a specific pattern, these areas automatically result in precise dashed openings on the mask.

[0076] A UV LED system is then used to expose the flexographic plate with UV light at a precise and constant energy level evenly distributed across the plate. The UV light, which passes through the mask openings, hardens the polymer structure in the areas of the plate corresponding to the holes in the mask, thus forming a dashed relief structure that represents the raised portions of the flexographic plate after the plate is treated to wash away the uncured polymer.

[0077] The repeating dashes shown as having a single pixel thickness are not limited to the depicted repeat distances and dash frequencies. Figure 1B The embodiment in which the lines are oriented at 135 degrees is generally equivalent to the embodiment in which the lines are oriented at 135 degrees. Figure 1A The pattern depicted at 45 degrees.

[0078] In other embodiments, imperfections during imaging in the imaging device (optical aberrations, imaging direction and skew, etc.) may result in suboptimal imaging for a single orientation pattern. Therefore, in some embodiments, a pattern that mixes 45 and 135 degree orientations may be used, such as Figure 4A 、 4B , 4C and 4D depict patterns 400, 410, 420 and 430.

[0079] exist Figure 4A In the surface screen pattern depicted in , each dashed line comprises four (4) pixels "on" and two (2) pixels "off," where lines of the same orientation have a vertical offset of 6 pixels, and where lines of opposite orientation are interwoven so that dashes of one orientation are centered in the space between dashes of the opposite orientation. Another way to represent the 4 pixels on, 2 pixels off design is to characterize adjacent dashes in the same orientation aligned along a common line as having a 2x2 pixel square located between them. Figure 5A A magnified microscopic image depicting the surface of the resulting printing plate was captured, with white areas corresponding to raised, ink-bearing areas of the printing plate and black areas corresponding to non-ink-bearing areas of the printing plate.

[0080] exist Figure 4B In the surface screen pattern depicted in , each dash comprises four (4) dashes on and four (4) dashes off (adjacent dashes in the same orientation aligned along a common line have a 4×4 pixel square located between them), with a vertical offset of eight (8) pixels between lines of the same orientation, and lines of opposite orientation are interwoven so that dashes of one orientation are centered in the space between dashes of opposite orientation.

[0081] exist Figure 4C In the surface screen pattern depicted in , the pattern includes two pixels on and two pixels off (adjacent dashed lines in the same orientation aligned along a common line have a 2×2 pixel square located between them), where the lines of the same orientation are offset by 4 vertical pixels (i.e., have a gap of three vertical pixels between them), and the lines of opposite orientation are interwoven so that the dashed lines of one orientation are centered in the space between the dashed lines of the opposite orientation. Figure 5B A magnified microscopic image capture depicting the surface of a portion of the resulting printing plate created after applying a pattern to a bitmap corresponding to solid color reproduction areas, where the white areas correspond to raised, ink-bearing areas of the printing plate and the black areas correspond to non-ink-bearing areas of the printing plate.

[0082] exist Figure 4D In the surface screen pattern depicted in , the pattern includes three pixels on and three pixels off (adjacent dashed lines in the same orientation aligned along a common line have a 3×3 pixel square located between them), where the lines of the same orientation are offset by 6 vertical pixels (i.e., have a gap of 5 vertical pixels between them), and the lines of opposite orientation are interwoven so that the dashed lines of one orientation are centered in the space between the dashed lines of the opposite orientation.

[0083] Although depicted in many of the figures with embodiments in which dashed line segments are aligned with one another to form diagonal lines having angles of 45 or 135 degrees, it will be appreciated that variations may be provided in which the line segments do not form such lines. For example, the dashed lines may be arranged in columns, wherein the dashed lines of adjacent columns of the same orientation are not aligned with one another to form straight lines. Figure 4E Describe this surface screen printing pattern. Figure 4E The pattern depicted in the exemplary embodiment of includes dashes of three pixels each, where adjacent dashes of the same orientation are not aligned along a common line and have a 1×3 pixel group located between them. Another way to express this pattern is to say that the dashes of the same orientation are distributed in columns that are three pixels wide, where the dashes of the same orientation are offset by 4 vertical pixels between corresponding points of the dashes in the same column (thus leaving a gap of 3 vertical pixels). The columns of pixels of different orientations are alternating, where the dashes of opposite orientations are aligned so that the top-most pixel of each dash of one orientation is horizontally aligned with the bottom-most pixel of the adjacent dash of the opposite orientation.

[0084] Figure 6A and 6B Each depiction is applied Figure 4EA magnified microscopic image of the surface of a portion of the resulting printing plate, created after screen printing, is captured, where the white areas correspond to the raised, ink-bearing areas of the printing plate, while the black areas correspond to the non-ink-bearing areas of the printing plate. To illustrate scale, the line shown in both figures corresponds to a distance of 750 microns. Figure 6A The plate portion depicted in is created from a mask imaged using a first pulse amplitude and a first pulse width, while Figure 6B The portion of the plate depicted in FIG is created from a mask imaged using a first pulse amplitude and a second pulse width that is relatively larger than the first pulse width (meaning corresponding to Figure 6B The mask ratio corresponds to Figure 6A The mask receives more laser energy per imaging feature).

[0085] As noted above with respect to Table 1, the match between pattern size and anilox roll line count can optimize printing performance. Thus, screens can be provided in a variety of single and dual orientation designs that vary in size to optimize the match with the anilox roll line count.

[0086] In some embodiments, the repeating dashes may have a thickness of multiple pixels, wherein the repeating distance is increased relative to a single pixel pattern so that the blank space between the dashes is at least greater than the thickness of the dashes. In this embodiment, standard imaging technology may be used instead of CDI P+ technology. Figure 9A A bitmap depicting an exemplary dash pattern having a thickness of 2 pixels, and Figure 9B Depicted is a bitmap of an exemplary dash pattern having a thickness of 3 pixels.

[0087] like Figure 9A , each dash comprises a total of 8 pixels: 4 pixels on the diagonal, 2 pixels wide (e.g., two single-pixel constituent dashes of 4 pixels length substantially side by side). Thus, as used herein, "thickness" refers to the number of single-pixel dashes of the same size grouped side by side. Each of the two side-by-side single-pixel constituent dashes of 4 pixels length has a gap of 2 off pixels between the on pixels in the same line and an offset of 6 horizontal pixels horizontally (creating a gap of 4 off pixels horizontally between each 2-pixel thick dash). The dashes are aligned in columns with a single-pixel space between columns and in rows with a double-pixel space between rows. As used herein, the term "constituent dash" refers to a single-pixel dash that, together with other single-pixel dashes formed by adjacent contact pixels, forms a dash having a multi-pixel thickness. "Adjacent contact pixels," as used herein, refers to pixels that share a common side or have vertices that share a common point at their respective corners. Therefore, each pixel has 8 neighboring touching pixels as the term is used herein.

[0088] like Figure 9B The dashes are arranged in a grid, each comprising a total of 12 pixels: 4 pixels on the diagonal, 3 pixels wide (e.g., three single-pixel dashes of 4 pixels length essentially side by side). The single-pixel dashes are aligned to form an arrow shape, with the topmost pixel of the middle single-pixel dash forming the arrow head, and the bottommost pixel of the outward single-pixel dashes being used for the tail. Each of the two side-by-side single-pixel dashes of 4 pixels length has a gap of 2 off pixels between on pixels in the same line, and is offset horizontally by 6 horizontal pixels (a gap of 3 off pixels is created horizontally between the middle portion of a 3 pixel thick dash, 4 off pixels at the arrow head, and 5 off pixels at the tail). The dashes are aligned in columns with a single-pixel space between columns, and in rows with a single-pixel space between rows.

[0089] Depicted Figure 9A and 9B The pattern is shown with dashed lines at a 45-degree angle, but variations at 135 degrees are also available. Similarly, while depicted in 2-pixel and 3-pixel variations, it should be understood that multi-pixel line thicknesses greater than 3 pixels may also be used. Furthermore, while all multi-pixel variations depicted have a single orientation, it should be understood that mixed orientations at 45- and 135-degree angles may be provided.

[0090] It is worth noting that the reversed Figure 9A and 9B The mirror image will result in a pattern at an angle of 135 degrees, such as Figure 9C As shown in the figure, Figure 9C yes Figure 9B A mirror image of the pattern of 9B inverted on the X (horizontal) axis (or both the X and Y axes) may also be provided. For illustration purposes, a mirror image of the pattern of 9B inverted on the X axis forms Figure 9D, wherein the arrow formed by 3 pixel shapes is pointing downward 45 degrees (i.e., -45 degrees), and the mirror image of the pattern of 9B reversed on the X-axis and Y-axis (or alternatively characterized as a 180 ° rotation of the pattern of 9B) forms a pattern, wherein the arrow formed by 3 pixel shapes is pointing downward 135 degrees (i.e., -135 degrees). Therefore, the modification of any single pattern can be referred to as having a short dash oriented at 45 degrees, 135 degrees, -45 degrees or -135 degrees or a combination thereof. Therefore, when any particular pattern is mentioned in this article, it should be understood that equivalent patterns that are mirror images (reversed on either or both axes), rotations (preferably in multiples of 90 degrees) or result in short dashes oriented at positive or negative 45 or 135 degrees are considered to be their equivalents. It is worth noting that while the single pixel design is identical with orientations of -45 and 135 degrees (or 45 and -135 degrees), the multi-pixel dash design can have variations in these orientations, and thus can provide all combinations of 45, 135, -45, and 135 orientations (e.g., including sequentially Figure 9B 、 9C , 9D and 9E).

[0091] Thus, all patterns depicted herein can be generally described as comprising a plurality of dashed lines, wherein each dashed line or its constituent dashed lines have the same number (M) of two or more adjacent on pixels in length and the same number (T) of one or more pixels in thickness or width, each dashed line having an orientation of plus or minus 45 degrees or 135 degrees, or a combination thereof. In embodiments where pixels of the same orientation are aligned to form diagonal lines, these lines can be characterized as dashed lines comprising M on pixels and N off pixels, with a vertical offset between lines of V pixels. Table 1 shows the corresponding values ​​of M, N, and T for each correlation graph:

[0092] Table 1

[0093] <![CDATA[ Figure No. ]]> <![CDATA[ M ]]> <![CDATA[ N ]]> <![CDATA[ T ]]> <![CDATA[ V ]]> 1A, 1B 4 2 1 6 4A 4 2 1 6 4B 4 4 1 8 4C 2 2 1 4 4D 3 3 1 6 9A, 9C, 9D, 9E 4 2 2 6 9B 4 2 3 6

[0094] All patterns depicted herein include dashed lines where line segments with the same orientation are aligned orthogonally in the same rows and columns. Figure 4E (where columns of dashed lines of the same orientation are spaced from one another such that the dashed lines of the same orientation do not form aligned diagonals), rows and columns having the same orientation are identical, such dashed lines are aligned in ordered rows and columns, although columns of dashed lines of different orientations alternate and rows of dashed lines of the same orientation overlap one another (i.e., some single-pixel rows contain a top pixel for a dashed line in one orientation and a bottom pixel for a dashed line in another orientation).

[0095] In some embodiments, a pattern of multi-pixel thick dashes may have an orthogonal alignment of dashes, but each dash may include a collection of constituent single-pixel dashes, where at least one of the constituent single-pixel dashes has more pixels than one or more of the other dashes. For example, Figure 9F The patterns depicted in Figure 9B The pattern depicted in the example differs in that the middle single-pixel dash is composed of 5 on-pixels instead of 4, thus forming arrows on either side instead of Figures 9B-9E The arrows with different heads and tails are formed in the pattern. It should also be noted that Figures 9B-9E For designs depicted in that include tail pixels that are not adjacent to other pixels on three sides, such pixels may not be completely or reliably formed in the plate because they do not form a 2×2 checkerboard that would result in automatic enhancement, these designs can effectively form shapes on the plate that would be equivalent to features in which these pixels were not present at all, which can still give acceptable performance.

[0096] Finally, check Figure 9F Another way to think about the design is that it defines a pattern of 3 pixel diagonals parallel to line 902, with an orthogonal grid of 1 pixel horizontal and vertical strokes 904 spaced 6 pixels apart being superimposed to close any open pixels in the path of these strokes. The advantage of the orthogonal orientation of the strokes in the grid is that regardless of rotation or mirror inversion of the design, the strokes remain orthogonally aligned.

[0097] However, acceptable patterns are not limited to orthogonally aligned patterns, and it should be understood that variations can be provided in which the positions of the line segments vary within a column or row so that the line segments are not orthogonally aligned, or alternatively, the strokes cutting through the diagonal grooves do not form an orthogonal grid.

[0098] Patterns as depicted herein can be represented in a variety of ways, but it should be understood that the basic principles and properties of the patterns can be widely applied. To the extent that dashes can be represented as having an "amplitude" (the length of the dash) and a "frequency" (the number of dashes per unit length), and lines have a "spacing" (all of which can define a "density" (the number of open pixels per unit area), it should be understood that many permutations and combinations of amplitude, frequency, spacing, and density can be applied.

[0099] Although primarily described herein with respect to the specific utility of applying surface patterns as disclosed herein to solid color reproduction areas, it should be noted that patterns can also be applied to halftone areas (e.g., areas formed by individual dots or solid or semi-solid color areas formed by multiple adjacent dots). Figure 10A bitmap corresponding to an exemplary halftone area including a plurality of halftone dots 1002 is shown. In the depicted embodiment, each dot has a guard ring 1004 corresponding to the outline of the dot. When a surface pattern is applied to a halftone dot having such a guard ring, the pixels within the ring are kept "on" rather than turned off to match the surface screen print pattern. In other embodiments, the surface pattern may be applied without the guard ring. Although in Figure 10 , the guard ring is depicted with a thickness of 4 pixels, but the present invention is not limited to the use of a guard ring of any particular pixel thickness. In fact, in some embodiments, the thickness can be varied from point to point, such as using a relatively large thickness for a relatively low screen percentage and applying a guard ring thickness gradient that varies inversely with the screen percentage. The use of surface screen printing in halftone dots can be phased in at a certain threshold and only used for screen percentages above that threshold (such as, for example, without limitation, at approximately 70% screen percentage). Thus, the thickness of the guard ring can be varied in such a way that the guard ring has such a relatively large thickness below a lower threshold (e.g., 70% screen percentage) that it completely prevents the application of the surface pattern, and has a zero or near-zero thickness above an upper threshold (e.g., 90%) that is close to solid color reproduction, such that no guard ring is applied at all. The application of surface screen to the surface of the halftone dot shape creates similar surface roughness, and its benefits for retaining ink when printing, as provided by applying a surface pattern as disclosed herein to solid color reproduction areas.

[0100] The methods and processes as described herein can be implemented on any printing plate manufacturing system known in the art. Such a system for creating a printing plate comprises at least a computer processor and a digital memory accessible to the computer processor, the digital memory embodying non-transitory machine-readable instructions for performing any method of creating a bitmap as described herein. An imager controllable by the processor is configured to apply the bitmap to a mask by forming a pattern of holes in the mask corresponding to the bitmap. An exposure unit (optionally controlled by the processor) is configured to expose the photopolymer printing plate to actinic radiation through the mask. One or more post-exposure units (such as a washing unit) are configured to remove uncured photopolymer from the printing plate. The imager may include a laser for forming holes in the mask, in which case the system is configured to apply a first, relatively large laser power to features in the bitmap that define a 2×2 checkerboard pattern and a second, relatively small laser power to features in the bitmap that do not define a 2×2 checkerboard pattern.

[0101] like Figure 11As depicted in FIG, an exemplary system 1100 for performing the present invention includes a processor 1102 having access to a computer storage medium 1104 containing non-transitory machine-readable instructions stored on the medium. The computer storage medium may include any type of computer storage medium known in the art or still widely implemented (including magnetic, optical, flash memory, etc.), and may include portable media, media co-located with one or more associated processors, such as in a desktop or laptop computer or mobile device, and media on a server or otherwise accessible via a network (such as, without limitation, via the Internet). The system may also include a display device 1106 configured to present visual information to a human user, and a user interface for receiving input, such as instructions from a human user. The user interface may include visual images rendered on the display device 1106 as part of a graphical user interface (GUI), and any type of user input device 1108 known in the art. Suitable user input devices include, for example, a mouse, trackball or other cursor control and selection device, a keypad for entering alphanumeric instructions, and / or a touch screen for allowing a user to manipulate images on a display device. Touch screen implementation can be configured to allow the user to use stylus or finger or multiple fingers to draw graphic images or otherwise manipulate the screen to select radio buttons or items from a menu such as a drop-down menu or to select alphanumeric characters on a virtual keyboard. The display / user interface can include a mobile device connected to the processor via a wired or wireless network. The processor (which can include multiple processors communicating with each other in multiple locations) can reside locally, remotely reside on a network (including via the Internet) or partially reside on a mobile device. The present invention is not limited to any specific computer system, computer processor, display type, memory type or user input device for performing the present invention.

[0102] The system 1100 may also be integrated with other components of a workflow for creating printing plates, including, but not limited to, an imager 1120 and an exposure unit 1130. The processor may be part of an integrated system that controls multiple aspects of the platemaking workflow, including the exposure unit 1130 (which, in some embodiments, may also receive imagewise information specific to printing or non-printing features on the plate), plate washing (or other plate handling equipment) 1140, and a lithographic system 1150 for applying ink to a web of sheet material using printing plates created according to aspects of the present invention. Although described herein with respect to imaging printing plates using LAM and UV exposure techniques, it should be understood that the present invention is not limited to any particular platemaking method and may include, for example, other masking techniques and additive manufacturing without limitation.

[0103] Although not limited to use with any particular process conditions, the systems and methods as described herein may be particularly well suited for implementation at relatively high resolutions. For example, certain patterns as described herein may be particularly useful at resolutions of 4000 dpi or greater. In general, patterns as described herein may work best when certain relationships between absolute pattern structure dimensions and printing conditions (e.g., anilox roller lines per centimeter as described in more detail above) are optimized. Some of the finer structured patterns (having relatively lower densities - including fewer imaging pixels per pattern element) may also be particularly well suited for relatively coarser document resolutions, while some of the coarser structured patterns (having relatively higher densities - including more imaging pixels per pattern element) may be particularly well suited for relatively finer document resolutions. For example, Figure 4C The patterns depicted in have been shown to show a favorable increase in solid ink density (SID) at a 2540 DPI file resolution, while certain other patterns (e.g., having isolated dots as described in the '141 publication—rather than dashes as described herein) perform less favorably. Typically, densities greater than 1700 dots / cm 2 (17 dots per 10×10 pixels) pattern, including Figure 4C The pattern shown in and other patterns with isolated dots consistent with the disclosure of the '141 publication have more acceptable SIDs for a document resolution of 2540 DPI than patterns composed of isolated dots with a lower density. In general, patterns that begin dot bridging earlier at low pixel enhancements appear better than patterns that still have individual dots at high enhancements when used at relatively finer document resolutions.

[0104] Although the present invention is shown and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

Claims

1. A method of creating a bitmap for creating a printing plate for printing ink on a substrate, the method comprising: (a) defining the area of ​​the image intended to be printed with ink; (b) applying a halftone screen to the defined area, the screen comprising a pattern comprising a plurality of dashes having a plus or minus 45 degree orientation, a plus or minus 135 degree orientation, or a combination of two or more plus or minus 45 degree and 135 degree orientations; as well as (c) creating a bitmap embodying the application of the halftone screen to defined areas; in: (i) each dash or its constituent dashes comprises two or more adjacent contact pixels of the same number M in length and one or more adjacent contact pixels of the same number T in width; and (ii) Dashed lines having line segments with the same orientation are aligned orthogonally in the same rows and columns. The method according to claim 1 , wherein M is in the range of 2 to 4, and T is in the range of 1 to 3.

3. A method according to any one of the preceding claims 1-2, wherein each short dash comprises the same number T of pixels in width, where T is an odd number greater than 1, and each short dash comprises T constituent single-pixel short dashes, wherein at least one single-pixel short dash comprises M+1 adjacent contact pixels in length.

4. The method of any one of the preceding claims 1-2, wherein the pattern comprises alternating columns of dashed lines having a positive or negative 45 degree orientation and columns of dashed lines having a positive or negative 135 degree orientation. The method of claim 4 , wherein a topmost pixel of the dashed line having a 45-degree orientation is aligned with a bottommost pixel of the dashed line having a 135-degree orientation.

6. The method of any one of claims 1-2, wherein the dashes of M pixels are grouped in diagonals, with N pixels between adjacent dashes in the same diagonal, and wherein the dashes are offset from each other by a value of V vertical pixels. The method of claim 6 , wherein M is in the range of 2 to 4, N is in the range of 2 to 4, and V is in the range of 4 to 8. The method of claim 7 , wherein M=4, N=2, and V=6.

9. The method according to any one of the preceding claims 1-2, wherein T=1.

10. The method according to any one of claims 1-2, wherein T>1.

11. The method of any of the preceding claims 1-2, wherein the screen comprises a pattern selected from the group consisting of the patterns depicted in Figures 1A and 1B.

12. The method of any one of claims 1-2, wherein the screen comprises a pattern selected from the group consisting of the patterns depicted in Figures 4A, 4B, 4C, 4D, 4E, 9A, 9B, and mirror images and rotations thereof.

13. The method according to any one of claims 1-2, wherein the defined area is a pure color reproduction area.

14. The method of any one of claims 1-2, wherein the defined area is a halftone area.

15. A computer storage medium product embodying non-transitory machine-readable instructions corresponding to a bitmap generated by the method of any one of claims 1-14.

16. A method for creating a mask for creating a printing plate for printing ink on a substrate, the method comprising: Providing a bitmap created by the method according to any one of claims 1 to 14; as well as The bitmap is applied to the mask by forming a pattern of holes in the mask corresponding to the bitmap.

17. The method of claim 16, wherein the step of forming the hole comprises ablating a portion of the mask with a laser, and wherein when T=1, the laser is applied to features in the bitmap that define a 2×2 checkerboard pattern at a first laser power, and the laser is applied to features in the bitmap that do not define a 2×2 checkerboard pattern at a second laser power, wherein the first laser power is greater than the second laser power; and Wherein when T>1, the laser is applied with the same laser power to create each feature defined in the bitmap.

18. A mask imaged by the method of any one of claims 16-17.

19. A method for creating a printing plate for printing ink on a substrate, the method comprising: providing a printing plate having a mask created by the method of any one of claims 16-17; exposing the printing plate to actinic radiation through the apertures in the mask, thereby curing the portions of the printing plate that received the actinic radiation; as well as The printing plate is processed to remove uncured areas of the printing plate, thereby creating raised areas in the printing plate corresponding to the halftone screen in portions of the printing plate corresponding to defined areas of the image.

20. A printing form produced by the method according to claim 19.

21. A system for creating a printing plate, the system comprising: Computer processors; a digital memory accessible to the computer processor, the digital memory embodying non-transitory machine-readable instructions for execution by the method of creating a bitmap according to any one of claims 1-14; an imager, controllable by the processor, the imager configured to apply the bitmap to the mask by forming a pattern of holes in the mask corresponding to the bitmap; an exposure unit, optionally controlled by said processor, for exposing a photopolymer printing plate to actinic radiation through said mask; as well as Post-exposure unit for removing uncured photopolymer from the printing plate.

22. The system of claim 21 , wherein the imager comprises a laser for forming the apertures in the mask, and the system is configured to apply a first laser power to features in the bitmap that define a 2×2 checkerboard pattern and to apply a second laser power to features in the bitmap that do not define a 2×2 checkerboard pattern, wherein the first laser power is greater than the second laser power.

23. A method of printing, comprising: providing a printing plate produced by the method according to claim 20; applying a first ink to the printing plate; as well as The first ink is transferred to a substrate as a first ink layer in areas of the substrate corresponding to the defined areas of the image.

24. The method of claim 23, wherein the ink transferred to the substrate in the areas corresponding to defined areas is a background color, the method further comprising printing with at least a second ink over the first ink layer.

25. The method of claim 23 or 24, wherein the substrate comprises a transparent or translucent substrate.

26. The method of any one of claims 23-24, wherein the ink is a white ink.

Images