JP2006013688A - Color proof generating apparatus, color proof generating system, and dot image data output apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color proof generating apparatus, a color proof generating system, and a dot image data output apparatus, and program simply correcting a difference from color tones of ink printed matters in color proofing by exposure of a silver salt color photosensitive material. <P>SOLUTION: The color proof generating apparatus 1 includes: an edge detection circuit 81 for detecting a dot edge part in dot image data in the case of generating the color proof by exposing the silver salt color photosensitive materials by means of a plurality of light sources with different wavelengths on the basis of dot image data; a random number generator 82 for generating a random number; and a comparator 84 for deciding whether or not the detected edge part is effective on the basis of the generated random number. The color proof generating apparatus 1 executes the exposure by inverting the dot image data of the effective edge part to correct the dot gain. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color proof creation device that creates a color proof by exposing a recording medium based on halftone dot image data, a halftone image data output device that outputs halftone dot image data, and a color proof creation device. The present invention relates to a color proof creation system, a halftone image data output device, and a program.

  Conventionally, a proof material (color proof) is separately prepared for proofreading a color printed material, and the finished product is confirmed in advance before a production printing plate is prepared. For this reason, multi-valued image data is halftoned by a front system such as a halftone image data generating device to generate binary image data, and a color proof creating device based on the halftone image data by a plurality of light sources having different wavelengths. A silver salt color light-sensitive material is exposed to create a color proof (calibration product). In such a color proof creating apparatus, exposure is performed by setting a look-up table (LUT) corresponding to a combination of colors separated into Y, M, C, and K plates (for example, the following patents) Reference 1).

  However, color printing performed using ink has its own phenomenon such as dot gain (dot thickening). Therefore, color proof created by color proofing by exposure to silver salt color photosensitive material with a color proofing device. The image may have a color tone different from that of the actual printed material, and the image of the printed material may not be sufficiently reproduced.

For this reason, for example, Patent Document 2 below proposes an image conversion method in which binary image data is once converted into a multi-valued image and then converted into binary image data, but such image processing is complicated. Therefore, the calculation load becomes high and the cost of the apparatus increases.
JP-A-11-205622 JP 2002-290722 A Japanese Patent Laid-Open No. 10-264463

  In view of the above-described problems of the prior art, the present invention provides a color proof that can be easily corrected for a difference in color tone with respect to an ink print in a color proof created by exposing a recording medium based on halftone dot image data. An object is to provide a proof creation device, a color proof creation system, a halftone image data output device, and a program.

  In order to achieve the above object, a color proof creating apparatus according to the present invention is a color proof creating apparatus for creating a color proof by exposing a recording medium based on binary halftone image data, wherein the halftone dot is created. Means for detecting edge portions of halftone dots in image data, random number generating means for generating random numbers, threshold setting means for setting thresholds, and the detected random number value by comparison with the set threshold value. Determining means for determining whether or not the edge portion is valid, and performing the exposure after reversing the halftone image data of the edge portion validated by the determining means.

  According to this color proof creation device, the edge portion of a halftone dot is detected, and the halftone dot image data of the edge portion that is validated based on a random number is inverted, so that the pixel position is determined relative to the random position of the edge portion. Since the inversion is performed, the dot gain of the halftone dot can be adjusted without generating an unnatural image such as moiré or tone jump, and the gradation density of the halftone image can be corrected. For this reason, the difference in color tone with respect to the ink print can be easily corrected in the color proof. For example, the gradation density of a halftone image is obtained by performing a thickening process that thickens a halftone dot at the outer edge of the edge portion that has been validated by reversing the halftone image data or a process that thins the halftone dot at the inner edge. Can be corrected.

  Another color proof creating apparatus according to the present invention is a color proof creating apparatus that creates a color proof by exposing a recording medium based on binary halftone dot image data, and sets an exposure amount at the time of the exposure. A plurality of exposure amount setting means, a means for detecting a halftone dot edge portion in the halftone image data, a random number generating means for generating a random number, a threshold setting means for setting a threshold, and the generated random value Determination means for determining whether or not the detected edge portion is effective by comparison with the set threshold value, and an edge portion that is enabled by the determination means when executing the exposure, and The exposure amount setting means is switched between other portions.

  According to this color proof creation device, the edge portion of the halftone dot is detected, and the exposure amount setting means is switched between the edge portion that is made effective based on the random number and the other portion, so that the random edge portion is changed. Since the exposure amount is switched with respect to the position, the density can be adjusted, and the dot gain of the halftone dot can be adjusted without generating unnatural images such as moiré or tone jump. Thus, the gradation density of the halftone image can be corrected. For this reason, the difference in color tone with respect to the ink print can be easily corrected in the color proof. For example, there is a look-up table as the exposure amount setting means, and the density adjustment can be performed in the boundary region of the halftone dot of the effective edge portion by switching the look-up table.

  According to the color proof creating system of the present invention, a halftone dot image data output device that outputs binary halftone dot image data, and a recording medium is exposed based on the halftone dot image data from the halftone dot image data output device. A color proof creation system connected to a color proof creation device for creating a color proof, wherein the halftone image data output device includes means for detecting an edge portion of a halftone dot in the halftone image data, and a random number Random number generation means for generating a threshold value, threshold value setting means for setting a threshold value, determination means for determining whether the detected edge portion is valid by comparing the generated random number value and the set threshold value, The halftone dot image data of the edge portion validated by the determination means is inverted and output to the color proof creating apparatus.

  According to this color proof creation system, the halftone dot edge portion is detected by the halftone dot image data output device, and the halftone dot image data made effective based on the random number is inverted, and then the halftone dot image data is converted. By outputting, pixel inversion is performed at random positions in the edge portion, so that dot gain of halftone dots can be adjusted without generating unnatural images such as moire and tone jump, for example. This makes it possible to correct the gradation density of the halftone image. For this reason, the difference in color tone with respect to the ink print can be easily corrected in the color proof. It should be noted that, for example, a halftone image is obtained by performing thickening processing for thickening halftone dots at the outer edge of the edge portion that has been validated by inversion of the halftone image data or thinning halftone dots at the inner edge. Tonal density can be corrected.

  A halftone dot image data output device according to the present invention is a halftone dot image data output device for outputting a halftone dot image data to a color proof producing device for producing a color proof by exposing a recording medium based on binary halftone dot image data. A dot image data output device comprising: means for detecting an edge portion of a halftone dot in the halftone dot image data; random number generating means for generating a random number; threshold setting means for setting a threshold; and the generated random value Determination means for determining whether the detected edge portion is valid by comparison with the set threshold value, and after reversing the halftone image data of the edge portion validated by the determination means It is characterized by outputting.

  According to this halftone image data output device, by detecting the edge portion of the halftone dot and inverting the halftone image data of the edge portion that is validated based on the random number, the halftone image data is output, Since pixel inversion is performed at random positions in the edge portion, it is possible to adjust the dot gain of halftone dots without generating unnatural images such as moire or tone jump. The gradation density of the image can be corrected. For this reason, the difference in color tone with respect to the ink print can be easily corrected in the color proof. It should be noted that, for example, a halftone image is obtained by performing thickening processing for thickening halftone dots at the outer edge of the edge portion that has been validated by inversion of the halftone image data or thinning halftone dots at the inner edge. Tonal density can be corrected.

  The program according to the present invention includes a halftone dot image data output device that is connected to a color proof creation device that creates a color proof by exposing a recording medium based on binary halftone image data and outputs the halftone image data. A program for a computer comprising: a step of setting a threshold; a step of detecting an edge portion of a halftone dot in the halftone dot image data; a step of generating a random number; and the generated random number value is set. A step of determining whether or not the detected edge portion is valid by comparing with a threshold value, and a step of inverting the halftone image data of the validated edge portion and outputting to the computer It is characterized by making it.

  According to this program, the halftone dot edge portion is detected in the halftone dot image data output device, and the halftone dot image data at the edge portion made effective based on the random number is inverted, and then the halftone dot image data is output. Thus, since the pixels are inverted with respect to the random position of the edge portion, it becomes possible to adjust the dot gain of the halftone dots without generating an unnatural image such as moiré or tone jump, for example. The gradation density of the halftone image can be corrected. For this reason, the difference in color tone with respect to the ink print can be easily corrected in the color proof. It should be noted that, for example, a halftone image is obtained by performing thickening processing for thickening halftone dots at the outer edge of the edge portion that has been validated by inversion of the halftone image data or thinning halftone dots at the inner edge. Tonal density can be corrected.

  According to the color proof creation device, the color proof creation system, the halftone image data output device, and the program of the present invention, the edge portion of the halftone dot is detected, and whether or not the edge portion detected based on the random number is valid. Therefore, the tone density of the halftone dot image can be corrected, so that the difference in color tone with respect to the ink print can be easily corrected in color proofing.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically illustrating a configuration example of a printing system including a color proof creation system according to the present embodiment. FIG. 2 is a view of the inside of the color proof producing apparatus of FIG. 1 as viewed from the front side. FIG. 3 is a plan view of the main part of the color proof producing apparatus shown in FIG. 2 as viewed from above.

  As shown in FIG. 1, the printing system inputs image data such as PS (PostScript) data from a client terminal 1A of a printing factory to an RIP (Raster Image Processor) 2 that is an image processing apparatus, and the RIP 2 rasterizes PS data. Data converted to image and raster / image converted by RIP2 is sent to CTP (Computer Tow Plate) 3 which is a device for creating a digital original directly for printing, while creating a color proof Configured to generate binary halftone dot image data and to create a color group by the color proof creation device 1 based on the halftone dot image data. Has been.

  The halftone image data output device 100 and the color proof creation device 1 shown in FIG. 1 constitute a color proof creation system, and this color proof creation system uses a pattern, color tone, text, characters, etc. to be printed out when printing at a printing factory. Create and output a color proof (calibration sample) to confirm the above. The color proof, moire, unevenness, etc. are confirmed by this color proof, an original plate is created by CTP3 in FIG.

  As shown in FIG. 2, the color proof producing apparatus 1 according to this embodiment exposes a silver salt color photosensitive material (hereinafter also simply referred to as “photosensitive material” or “photosensitive paper”) in order to create a color proof. And an exposure unit 11 for forming an image and a developing unit 21 for developing the exposed photosensitive material.

  As shown in FIG. 2, the exposure unit 11 of the color proof producing apparatus 1 is loaded with a loading unit 12 for loading and storing a dedicated cartridge 13 containing a photosensitive paper, which is a sheet-like photosensitive material wound inside a roll. 12 ', a feeding unit 14 including a pair of transport rollers 40, 41, and 42 for feeding photosensitive paper from the cartridge 13 loaded in the loading units 12 and 12', and a photosensitive unit fed from the feeding unit 14. A drum 10 that rotates in the rotation direction R for main scanning while vacuum sucking and holding the paper S on the outer peripheral surface, an optical unit 16 that exposes a light beam such as LED light to the photosensitive paper on the drum 10, and an optical A sub-scanning unit 17 that transports the unit 16 in the sub-scanning direction (vertical direction in FIG. 1) H (FIG. 3) for sub-scanning, and a peeling member 15 that peels off the photosensitive paper on the drum 10 after image recording. . The exposed photosensitive paper is conveyed to the developing unit 21 through the outlet 19 and the connecting portion 19a.

  The color proof producing apparatus 1 shown in FIG. 2 further includes a driven roller 31 that is arranged on the downstream side of the pair of conveying rollers 42 and is driven to rotate in accordance with the conveyance of the photosensitive paper that is fed toward the drum 10. The driven roller 31 transported by the drum 10, the accumulating guide member 18 that guides the photosensitive paper when the photosensitive paper peeled from the drum 10 by the peeling member 15 is transported by the drum 10 and the driven roller 31, and the accumulating guide member 18. A pair of conveying rollers 32 further conveys the fed photosensitive paper to the outlet 19, and a part of the accumulating guide member 18 is opened to accumulate the photosensitive paper that has reached the conveying roller pair 32. The accumulator 30 and a detection sensor 33 for detecting the leading edge of the photosensitive paper disposed in the vicinity of the downstream side of the conveying roller pair 32 are provided.

  A relatively narrow driven roller 43 disposed in the vicinity of the downstream side of the conveying roller pair 42 is driven to rotate along with the movement of the recording paper, and a rotary encoder (not shown) is connected coaxially with the driven roller 43. . By rotating the rotary encoder together with the driven roller 43 and measuring the rotation amount, the length of the photosensitive paper wound around the rotary drum 10 through the pair of conveying rollers 42 can be obtained. The downstream conveying roller pair 32 has a one-way clutch structure and can freely rotate in the direction of feeding the photosensitive paper downstream.

  A cut portion 10a for cutting the photosensitive paper is disposed in the vicinity of the downstream side of the pair of conveyance rollers 40 and 41 in FIG. 2, and each cut portion 10a has a rotary cutter that is rotationally driven by a motor (not shown). The photosensitive paper is cut into a predetermined length based on the above-described measurement of the length of the photosensitive paper.

  The developing unit 21 in FIG. 2 performs wet development on the exposed photosensitive paper sent from the exposure unit 11, and includes a developing unit 23 that performs development processing of the photosensitive paper, a fixing unit 24 that performs fixing processing, and a stable unit. A stabilization unit 25 that performs processing, a drying unit 26 that performs drying processing, and a discharge unit 27 that discharges the dried photosensitive paper to the outside by a pair of conveyance rollers 27a and the like.

  As shown in FIG. 3, in the drum 10 of the color proof producing apparatus 1, the rotating shaft 14a of the rotating shaft portion 14 ′ and the rotating shaft 15a of the rotating shaft portion 18a can rotate to the support bases 34a and 34b via the bearings 33a and 33b. Is pivotally supported. One rotating shaft 15a of the drum 10 is provided with a driving pulley 35a. The driving pulley 35a is connected to an output pulley 35b of a drum driving pulse motor M6 by a belt 36, and is driven by the drum driving pulse motor M6. 10 rotates. The rotary shaft 15a of the drum 10 is provided with a rotary encoder 37, which outputs a pulse signal for rotation and is used for pixel clock control synchronized with the rotation of the drum.

  The other rotating shaft 14a of the drum 10 is connected to the suction blower P1. A large number of suction holes 31c are formed on the surface of the drum 10 so as to extend linearly in the direction of the rotation axis. The inside of the drum 10 is depressurized by driving the suction blower P1, and the photosensitive paper is sucked onto the surface of the drum 10. .

  The optical unit 16 is configured to be movable in parallel with the drum axis by the sub-scanning unit 17, and performs image writing by exposing the photosensitive paper adsorbed to the drum 10 with a light beam. As shown in FIG. 3, the optical unit 16 includes an LED unit 320, an LED unit 321, and an LED unit 322 as light sources having different three wavelengths. Each LED unit 320, 321, 322 includes a light emitting diode (LED) disposed on a substrate for a plurality of channels, and the light beam from each LED unit 320, 321, 322 passes through mirrors 325, 326, 327. Thus, the image is exposed from the condenser lens 331 onto the photosensitive paper on the drum 10. The exposure shutter 332 is opened / closed by an exposure solenoid 333 to open / close the optical path at the start / end of exposure.

  Further, the plurality of LED units 320, 321, and 322 are configured to emit light of, for example, B (blue) having a wavelength of about 450 nm, G (green) having a wavelength of about 540 nm, and R (red) having a wavelength of about 650 nm. When a silver salt color photosensitive material is exposed by each LED unit, Y (yellow) is developed by B, M (magenta) is produced by R, and C (cyan) is produced by G.

  The optical unit 16 is fixed to a moving belt 340 and guided by a pair of guide rails 341 and 342 so as to be movable in the sub-scanning direction H parallel to the drum axis and in the opposite direction H ′. The moving belt 340 is stretched over a pair of pulleys 343 and 344. One pulley 344 is connected to the output shaft 345 of the sub-scanning motor M7, and the optical unit 16 is sub-scanned in parallel with the drum axis by driving the sub-scanning motor M7. Move in the direction H and in the opposite direction H ′.

  Further, as shown in FIG. 3, a photometric unit 57 composed of a light receiving element such as a photodiode is disposed at an extended position parallel to the drum axis of the outer peripheral surface of the rotary drum 10, and the position of the home position in FIG. The optical unit 16 moves slightly in the direction H ′, and the light beams from the LED units 320 to 322 enter the photometry unit 57, whereby the light amount of the light beam of each LED of each channel can be measured.

  As shown in FIG. 3, the suction blower P1 sucks the inside of the drum 10 through the suction connecting pipe 51 'by an air suction pump, and negatively pressurizes the inside of the drum 10 before the exposure unit 11 starts the exposure, thereby adsorbing the photosensitive paper to the outer peripheral surface. To do.

  <First Embodiment>

  Next, a color proof creating apparatus according to the first embodiment will be described with reference to FIGS. In the present embodiment, the halftone dot edge portion is detected based on the halftone dot image data input from the halftone dot image data output device 100 of FIG. 1, and the halftone dot image data that is validated based on the random number is inverted. This adjusts the dot gain of the halftone dots.

  FIG. 4 is a block diagram showing a flow of image data and a control system in the color proof producing apparatus of FIGS. FIG. 5 is a diagram schematically showing halftone dots in order to explain halftone edge detection performed by the edge detection circuit of FIG. FIG. 6 is a flowchart for explaining the operation of the color proof producing apparatus shown in FIGS.

  As shown in FIG. 4, the color proof creating apparatus 1 includes a halftone dot image data input unit 80 to which halftone dot image data generated by the halftone dot image data output apparatus 100 in FIG. An image data memory 88 for temporarily storing the halftone dot image data input from the halftone dot image data input unit 80, and an edge detection circuit 81 for detecting an edge portion of the halftone dot for the halftone dot image data output from the image data memory 88; The random number generator 82 for generating a random number, the threshold value setting unit 83 for setting a threshold value used for determining whether or not the detected edge is valid, and the set threshold value and the generated random number value are compared. For example, a comparator 84 that outputs a comparison result signal when the random value is large is provided.

  Note that the halftone image data generated and output by the halftone image data output device 100 is binary data of each version such as Y, M, C, K, and spot color. The image data memory 88 is a memory for storing at least three lines of image data including lines before and after the line for edge detection for 3 × 3 mask processing as shown in FIG. 5 described later.

  Further, the color proof creation device 1 determines whether or not the detected edge portion is valid by determining whether or not the detected edge portion data is output based on the comparison result signal from the comparator 84. AND circuit 85, the edge portion data validated from AND circuit 85 and the halftone dot image data output from image data memory 88 are inputted, and the halftone dot image data obtained by inverting the valid edge portion. An OR circuit 86 that outputs a light source, and a look-up table (LUT) 87 that creates light source driving values for driving the LED units 320 to 322 as exposure data based on the halftone image data from the OR circuit 86; Is provided.

  The color proof creating apparatus 1 further includes a plurality of D / A converters 55a, 55b, and 55c corresponding to the B, G, and R LED units 320 to 322 that convert the digital signal of the exposure data from the LUT 87 into an analog signal. And a plurality of drivers 56a, 56b, and 56c for directly analog-modulating and driving the LEDs of the LED units 320 to 322 by the analog signals from the D / A converters 55a to 55c.

  The edge detection circuit 81 in FIG. 4 detects a halftone dot edge portion in binary halftone image data using, for example, a 3 × 3 mask as shown in FIG. As shown in FIG. 5, “0” (no color) or “1” (colored) is detected for the target pixel g1 and the surrounding eight pixels g2 to g9, and the target pixel g1 has no color, and each pixel g2 For example, when at least one pixel out of g9 to g9, for example, the pixel g8 is colored as shown in FIG. 5, it is detected as an edge portion. The detection of the edge portion is performed for all pixels of the halftone dots in the halftone image data by sequentially changing the target pixel.

  In FIG. 4, when the edge portion detected by the AND circuit 85 is validated, the OR circuit 86, for example, inverts the pixel of interest g1 to “1” so that the pixels in the edge portion are colored. Point image data is output.

  Next, the operation of the color proof producing apparatus 1 of FIGS. 1 to 5 will be described with reference to the flowchart of FIG.

  The halftone image data output device 100 in FIG. 1 generates and outputs halftone image data based on the PS data, and this halftone image data is input to the color proof creation device 1 (S01). On the other hand, a threshold value is set by the threshold value setting unit 83 of FIG. 4 (S02).

  Next, halftone dot edge detection is performed on the input halftone image data (S03). Then, a random number is generated from the random number generator 82 of FIG. 4 (S04), and the random number value is compared with the set threshold value by the comparator 84 (S05).

  Next, it is determined whether or not the detected edge portion is valid based on the comparison result signal generated from the comparator 84 when the random number value is larger than the threshold value in the comparison, and the detected edge portion is detected and validated. Are reversed (S06). The halftone image data in which the pixels of the edge portion are inverted is output from the OR circuit 86 (S07), and is input to the LUT 87 for exposure (S08).

  For example, when a mask is used as shown in FIG. 5 and the pixel of interest g1 has no color and one of the pixels g2 to g9 is colored, the edge portion is detected, and the pixel of interest g1 is inverted with the color, and the inversion is performed. When the image data is valid, exposure is performed with image data in which the pixels at the edge portions are colored. When the image data is not valid, exposure is performed with the original image data.

  The photosensitive material that has been exposed as described above is transported and developed by the developing unit 21 (S09), and the photosensitive material on which an image has been formed is output as a color proof (S10).

  As described above, according to the color proof creation device of FIGS. 1 to 6, when creating a color proof, when an edge portion of a halftone dot is detected and the detected edge portion is validated based on a random number By reversing the pixel of interest, which has no color, and coloring the pixels at the edge portion, the pixels are inverted at random positions at the edge portions of the halftone dots. For this reason, for example, the dot gain (halftone dot thickness) of the proofreading ink print can be adjusted without generating an unnatural image such as moire or tone jump, and the tone density of the halftone image can be adjusted. The tone density of the halftone image can be corrected. For this reason, the difference in color tone with respect to the ink print can be easily corrected in the color proof.

  Further, the image processing of the present embodiment is simple in the apparatus because it only compares the random number value generated from the random number generator with the comparator and determines whether or not the detected edge portion is valid. It is only necessary to add a simple configuration, the calculation load is not high, and the cost of the apparatus is not increased.

  In addition, when the detected edge part is validated based on random numbers, the dot gain of the halftone dot is adjusted by inverting the pixel of interest that has no color and fattening the pixels adjacent to the edge part. An example of correction will be described. For example, as shown in FIG. 10, a pixel g20 corresponding to 20% is randomly added to the outside of each edge at a plurality of halftone dots G having an area gradation of 20% based on random numbers. Thereby, the gradation density can be increased, and the dot gain can be more effectively corrected as shown by the broken line in FIG. Note that the pixel g20 may be added inside each edge.

  In addition, when the detected edge portion is validated based on a random number, a modification is performed in which a pixel of interest that is colored is inverted, the inner pixel adjacent to the edge portion is made colorless, and is thinned This will be described with reference to FIGS.

  As shown in FIG. 12, when the OR circuit 86 in FIG. 4 is changed to an AND circuit 86a, the inner edge is detected by the edge detection circuit 81, and the edge portion detected by the AND circuit 85 is validated, the AND circuit 86a. Thus, for example, by reversing the pixel of interest to “0”, halftone dot image data in which the inner edge pixel has no color is output. Thus, for example, as shown in FIG. 13, the pixels gg indicated by the broken lines inside each edge at a plurality of halftone dots G are randomly rendered based on random numbers. Thereby, by reducing the gradation density, the dot gain of the halftone dot can be adjusted and corrected.

  <Second Embodiment>

  Next, the dot gain of the halftone dot is adjusted by detecting the edge portion of the halftone dot and switching the lookup table between the edge portion where the edge portion is detected and validated and the other portion. A color proof creating apparatus according to the second embodiment will be described with reference to FIG.

  FIG. 7 is a block diagram showing a flow of image data and a control system in the color proof producing apparatus according to the second embodiment.

  The color proof producing apparatus of FIG. 7 has substantially the same configuration as that of FIG. 4 except that the OR circuit is omitted and exposure is performed by switching a plurality of LUTs as compared to FIG.

  In the LUT 87, a first look-up table for each color plane data and another second look-up table of the same color for adjusting the density of each color plane data are set. The LUT 87 receives halftone dot image data, The LED units 320 to 322 are driven to output exposure data for exposing the photosensitive paper.

  7, when the edge detection circuit 81 detects the edge portion of the halftone dot and the comparator 84 compares the random value with the threshold value, the comparison result signal is input to the AND circuit. When the image data from the edge detection circuit 81 is input to the LUT 87, the edge portion detected and validated is exposed by the second lookup table.

  For example, in the edge detection circuit 81, when the pixel of interest g1 has no color as shown in FIG. 5 and one of the edge portions g2 to g9 is colored, the edge portion is detected, and the halftone dot of FIG. A pixel is added to a portion adjacent to the layer and exposed. Thereby, the dot gain can be adjusted and corrected as shown in FIGS.

  The color proof creating apparatus of FIG. 7 operates in the same manner as the flowchart of FIG. 6, detects the edge portion of the halftone dot in the halftone dot image data, and when it is validated based on the random number, the second look-up table If exposure is not performed, the exposure is performed using the first look-up table. As a result, the exposure amount is switched with respect to the random position of the edge portion of the halftone dot, so that the dot gain of the halftone dot is adjusted without generating an unnatural image such as moire or tone jump, for example. Therefore, the gradation density of the halftone image can be corrected. For this reason, the difference in color tone with respect to the ink print can be easily corrected in the color proof.

  Further, in the present embodiment, when each halftone dot G is thickened as shown in FIG. 14 as shown in FIG. 14, the look-up table is further set so that colored pixels are randomly high in density. The dot gain can be adjusted and corrected by using the pixel gh and the low pixel gl.

  Further, in the present embodiment, when the process of thinning each halftone dot G as shown in FIG. 13 is performed as shown in FIG. 15, pixels that are made colorless by setting a look-up table are randomly high in density. By making the pixel gh and the low pixel gl, the dot gain can be adjusted and corrected.

  <Third Embodiment>

  Next, an example in which the halftone dot edge portion is detected on the front system side such as a halftone dot image data output device to correct the tone density of the halftone dot image will be described. That is, FIG. 8 and FIG. 8 show the halftone image data generation apparatus of the color proof creation system of FIG. 1 in which another version is generated for the edge part in which the edge part is detected and validated in the halftone image data generation apparatus. This will be described with reference to FIG.

  FIG. 8 is a block diagram showing a flow of image data and a control system in the halftone image data generation device according to the third embodiment. FIG. 9 is a flowchart for explaining the operation of the color proof creation system shown in FIGS.

  As shown in FIG. 8, the halftone image data output device 100 generates a halftone dot image data based on multivalued image data such as PS data input from a client terminal via Ethernet or the like. A data generation unit 90; an image data memory 98 for temporarily storing the halftone image data generated by the halftone image data generation unit 90; and an edge portion of the halftone dot in the halftone image data output from the image data memory 98 is detected. An edge detection circuit 91 for generating a random number, a random number generator 92 for generating a random number, a threshold value setting unit 93 for setting a threshold value used for determining whether or not the detected edge part is valid, and a set threshold value and generation And a comparator 94 that outputs a comparison result signal when the random number value is large, for example.

  The halftone dot image data generated by the halftone dot image data generation unit 90 is binary data of each version such as Y, M, C, K, and spot color. The image data memory 98 is a memory for storing at least three lines of image data including lines before and after the line on which edge detection is performed for the 3 × 3 mask processing as shown in FIG.

  Further, the halftone image data output device 100 determines whether the detected edge portion is effective by determining whether or not the halftone image data from which the edge portion is detected is output based on the comparison result signal from the comparator 84. An AND circuit 95 for determining whether or not, the edge data validated from the AND circuit 95 and the halftone dot image data output from the image data memory 98 are inputted, and the halftone dot data validated is inputted. An OR circuit 96 that inverts and outputs the dot image data, and an image data output unit 97 that outputs the halftone image data from the OR circuit 96 to the color proof creation device 1 of FIGS. .

  The edge detection circuit 91 in FIG. 8 detects a halftone dot edge portion in the halftone image data in the same manner as described with reference to FIG.

  Next, the operation of the color proof creation system of FIGS. 1 to 3 and 8 will be described with reference to the flowchart of FIG.

  When image data such as PS data is input (S11), the halftone image data output device 100 in FIG. 1 generates halftone image data based on this image data (S12). On the other hand, a threshold value is set by the threshold value setting unit 93 of FIG. 8 (S13).

  Next, halftone dot edge detection is performed on the input halftone image data (S14). Then, a random number is generated from the random number generator 92 of FIG. 8 (S15), and the random number value is compared with the set threshold by the comparator 94 (S16).

  Next, it is determined whether or not the edge portion detected by the comparison result signal generated from the comparator 94 is valid when the random number value is larger than the threshold value in the comparison, and the detected and validated edge portion. The halftone dot image data in which the edge pixel is colored is input to the image data output unit 97 (S17).

  For example, when a mask is used as shown in FIG. 5 and the pixel of interest g1 has no color and one of the pixels g2 to g9 is colored, the edge portion is detected, and the pixel of interest g1 is inverted with the color, and the inversion is performed. When the image data is valid, image data in which the pixel at the edge is colored is output, and when the image data is not valid, the original image data is output.

  Next, the above-described halftone dot image data for each color is output from the image data output unit 97 to, for example, the color proof creating apparatus shown in FIGS. 1 to 3 (S18). 1 to 3, the silver salt color photosensitive material is exposed based on the above-described halftone dot image data (S19), and the exposed photosensitive material is conveyed and developed in the developing unit 21 ( S20), the photosensitive material on which the image has been formed is output as a color proof (S21).

  As described above, according to the color proof creation system of FIGS. 1 to 3, 8, and 9, the edge portion of a halftone dot is detected in a front system such as a halftone dot image data generation device, and based on a random number. The image data of the edge portion that has been validated is inverted, and the halftone dot image data in which the pixel of interest without color at the edge portion is colored is output to the color proof creation device to create a color proof. Pixel inversion is performed at random positions in the edge portion. For this reason, for example, the dot gain (halftone dot thickness) of the proofreading ink print can be adjusted without generating an unnatural image such as moire or tone jump, and the tone density of the halftone image can be adjusted. Can be corrected. For this reason, the difference in color tone with respect to the ink print can be easily corrected in the color proof. Thus, the dot gain can be adjusted and corrected as shown in FIGS.

  In the first to third embodiments as described above, each step when the color proof creating apparatus or the halftone image data generating apparatus operates as shown in FIG. 6 or FIG. The program stored in the storage unit can be read out, executed, and executed according to the program. Further, the halftone image data generation device of the third embodiment may be configured to be executed while being controlled by a computer in accordance with a program that performs the same processing as in FIG.

  As described above, the best mode for carrying out the present invention has been described. However, the present invention is not limited to these, and various modifications are possible within the scope of the technical idea of the present invention. For example, the color proof producing apparatus is not limited to an image recording apparatus in which a silver salt color photosensitive material is exposed and exposed to light beams of RGB with a plurality of light sources having different wavelengths as described above, for example, sequentially. The donor sheet is superimposed on the image receiving sheet, and the ink from the donor sheet is transferred to the image receiving sheet by irradiating a light beam for each of the C, M, Y, and K color plate image data. Then, it may be configured to perform surface sequential exposure so as to discharge the donor sheet irradiated with the light beam and to form an image on the image receiving sheet. For example, the above-mentioned Patent Document 3 (Japanese Patent Laid-Open No. 10-264463) may be used. The image recording apparatus proposed by the present applicant in Japanese Patent Publication No. When this image recording apparatus is used as the color proof creating apparatus 1 in FIG. 1, a halftone image data output apparatus or the like is configured correspondingly.

  The degree of dot gain adjustment and gradation density correction in FIGS. 4 and 8 can be changed by appropriately changing and setting the threshold value by the threshold setting unit 83 or 93.

  Further, the edge detection mask in FIG. 5 may be, for example, 5 × 5, and an edgeless detection is performed when a non-colored pixel is detected for the target pixel and a colored pixel is detected in an arbitrary detection mask. The number of colored peripheral pixels can be changed as appropriate.

  In the present embodiment, the halftone image data output apparatus according to the present invention has been described as an apparatus that generates halftone image data. However, the present invention is not limited to this, and is based on halftone image data generated by another apparatus. Of course, output may be performed to the color proof producing apparatus.

It is a figure showing roughly the whole color proof creation system by this embodiment. It is the figure which looked at the inside of the color proof production apparatus of FIG. 1 from the front side. It is the principal part top view which looked at the drum and optical unit of the color proof production apparatus of FIG. 2 from the upper part. It is a block diagram which shows the flow of the image data in the color proof production apparatus by 1st Embodiment, and a control system. FIG. 5 is a diagram schematically showing halftone dots in order to explain halftone dot edge detection performed by the edge detection circuit of FIG. 4. It is a flowchart for demonstrating operation | movement of the color proof production apparatus 1 of FIG. 1 thru | or FIG. It is a block diagram which shows the flow of the image data in the color proof production apparatus by 2nd Embodiment, and a control system. It is a block diagram which shows the flow of the image data in the halftone image data generation device by 3rd Embodiment, and a control system. It is a flowchart for demonstrating operation | movement of the color proof production system of FIGS. 1-3, FIG. It is a figure which shows a halftone dot typically in order to demonstrate the fattening process in each embodiment. It is a graph which shows notionally the relationship between a halftone dot area and a density for explaining adjustment of dot gain. It is the same block diagram as FIG. 4 which shows the modification of FIG. It is a figure which shows a halftone dot typically in order to demonstrate the process which makes a halftone dot thin in FIG. FIG. 8 is a diagram schematically showing halftone dots in order to explain pixel fattening processing of each halftone dot G in FIG. 7. FIG. 8 is a diagram schematically showing halftone dots in order to explain the process of thinning the pixels of each halftone dot G in FIG. 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color proof production apparatus 11 Exposure unit 21 Development unit 80 Halftone image data input part 81 Edge detection circuit 82 Random number generator 83 Threshold setting part 84 Comparator 85 AND circuit 86 OR circuit 87 Look-up table (LUT)
100 Halftone dot image data generation device (halftone dot image data output device)
90 halftone dot image data generation unit 91 edge detection circuit 92 random number generator 93 threshold value setting unit 94 comparator 95 AND circuit 96 OR circuit 97 image data output unit 320, 321, 322 LED unit (plural light sources)
S photosensitive paper g1 pixel of interest g2 to g9 pixels around pixel of interest g1

Claims (5)

A color proof creation device for creating a color proof by exposing a recording medium based on binary halftone image data,
Means for detecting an edge portion of a halftone dot in the halftone dot image data;
Random number generating means for generating a random number;
Threshold setting means for setting a threshold;
Determination means for determining whether or not the detected edge portion is valid by comparing the generated random number value and the set threshold value,
A color proof producing apparatus, wherein the exposure is executed after reversing the halftone image data of the edge portion validated by the judging means. A color proof creation device for creating a color proof by exposing a recording medium based on binary halftone image data,
A plurality of exposure amount setting means for setting an exposure amount at the time of the exposure;
Means for detecting an edge portion of a halftone dot in the halftone dot image data;
Random number generating means for generating a random number;
Threshold setting means for setting a threshold;
Determination means for determining whether or not the detected edge portion is valid by comparing the generated random number value and the set threshold value,
A color proof creating apparatus, wherein the exposure amount setting means is switched between an edge portion validated by the determination means and the other portion when executing the exposure. A halftone image data output device that outputs binary halftone image data, and a color proof creation device that creates a color proof by exposing a recording medium based on the halftone image data from the halftone image data output device And a color proof creation system to which
The halftone image data output device,
Means for detecting an edge portion of a halftone dot in the halftone dot image data;
Random number generating means for generating a random number;
Threshold setting means for setting a threshold;
Determination means for determining whether or not the detected edge portion is valid by comparing the generated random number value and the set threshold value,
A color proof creation system, wherein the halftone image data of the edge portion validated by the determination means is inverted and then output to the color proof creation device. A halftone dot image data output device for outputting the halftone dot image data to a color proof creation device that creates a color proof by exposing a recording medium based on binary halftone dot image data,
Means for detecting an edge portion of a halftone dot in the halftone dot image data;
Random number generating means for generating a random number;
Threshold setting means for setting a threshold;
Determination means for determining whether or not the detected edge portion is valid by comparing the generated random number value and the set threshold value,
A halftone dot image data output device which outputs after reversing halftone dot image data of an edge portion validated by the judging means. A program for a computer provided in a halftone image data output device connected to a color proof creation device for creating a color proof by exposing a recording medium based on binary halftone image data and outputting the halftone image data Because
Setting a threshold;
Detecting a halftone dot edge in the halftone image data;
Generating a random number;
Determining whether the detected edge portion is valid by comparing the generated random number value with the set threshold value;
Inverting the halftone dot image data of the validated edge portion and outputting the inverted image data, the program causing the computer to execute.

Images