JP2004223850A - Image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processor which applies image-processing to received printing data, outputs the processed data to a printing engine, and performs an effective trapping operation without enlarging the size of the processor and lowering the processing speed. <P>SOLUTION: This image processor 2 comprises a front processor 21 for converting the received printing data 1 to bitmap data to store it to a memory 22 and a rear processor 23 that processes the bitmap data stored in the memory 22 corresponding to the driving of the printing engine 3 and outputs the processed data to the printing engine 3. The rear processor 23 has the trapping operation means 25 for performing the trapping operation according to the bitmap data. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing apparatus that performs image processing on received print data and outputs the data after the image processing to a print engine. In particular, the present invention relates to an effective trapping process that does not cause an increase in apparatus scale and a reduction in processing speed. The present invention relates to an image processing apparatus capable of performing the following.
[0002]
[Prior art]
Generally, printing of a color image is performed by overlapping a plurality of color components. In such color image printing, usually, four colors of C (cyan), M (magenta), Y (yellow), and K (black) are used, and a printing operation is sequentially performed for each of these colors to obtain four colors. Are superimposed. Therefore, in such a color image printing, since the printing operation of each color is different, there is a case where a positional shift occurs between the output images of each color. In particular, in a tandem-type printer or the like that enables high-speed printing by making the printing mechanisms for each color independent, this misalignment tends to be large because the printing mechanisms for each color are independent.
[0003]
If such a displacement occurs, the image quality of the output image is degraded. In particular, if a phenomenon called so-called white spot occurs, in which a white portion that is not originally generated occurs at a boundary where the color changes due to the displacement, the image quality is deteriorated. Is bad. Therefore, conventionally, a trapping process has been proposed to prevent the image quality from being deteriorated due to the displacement.
[0004]
The trapping process is to add an extra color around a boundary (edge) where the color changes, and to prevent image quality deterioration due to white spots and the like even when a positional shift occurs. Specifically, using the image data to be printed before the printing operation, the edge portion where the color changes is detected, it is determined whether or not to perform the trapping process based on the color change status, etc. Changes the image data (color data) around the edge portion so that the image quality is not degraded even if a positional shift occurs. Such trapping processing is particularly necessary for a tandem-type printer having a large displacement.
[0005]
The following patent document (Japanese Patent Application Laid-Open No. 2002-165104) discloses an apparatus and method for such trapping processing, and includes four colors of C (cyan), M (magenta), Y (yellow), and K (black). Is described in which a region to which a color is to be added and a color to be added are determined using the data.
[0006]
[Patent Document 1]
JP-A-2002-165104
[0007]
[Problems to be solved by the invention]
Normally, an image processing apparatus such as a printer that performs color image printing includes a pre-processing portion that interprets print data transmitted from a personal computer and stores it as bitmap data, and an operation of an engine that executes printing. There is a post-processing portion that adds processing to the bitmap data and outputs the processed data to the engine at the time of printing in synchronization with. When the above-described trapping process is performed in the above-described pre-process, it takes time to perform the process, and there is a disadvantage that the printing speed is reduced. In particular, this problem is caused in a tandem-type printer characterized by high speed. .
[0008]
Also, when printing at a resolution higher than the resolution of the original image, if the trapping process is performed in the pre-processing, it is necessary to convert the image data to a high resolution at the pre-processing stage and store the bitmap data. Therefore, a large memory must be prepared, and the printing speed is reduced. On the other hand, in the case where only trapping processing is performed without performing conversion to a high resolution in the pre-processing, since the trapping processing is performed at the original resolution, the width of the trapping is widened and the image is blurred.
[0009]
FIG. 6 is a diagram for explaining such a problem. FIG. 6A shows a case where a trapping process is performed after conversion into a high resolution. C1 in the figure is an originally colored region, which is represented by 4 × 4 pixels by resolution conversion. D in the figure is an edge where the color changes, and a color is added to an area of one pixel outside (T1 in the figure) by trapping processing. On the other hand, FIG. 6B shows a case where trapping processing is performed at the original resolution, and C2 in FIG. 6 is an area corresponding to C1 in FIG. Is expressed. Therefore, when the trapping process is performed in the same manner, a color is added to the area for one pixel shown at T2 in the figure. FIG. 6C shows the result of the subsequent resolution conversion. As is clear from FIGS. 6A and 6C, when the trapping process is performed before the resolution conversion, the same region (C1 and C3) is added with the color (the region of FIG. 6C). T3) is spread, and the problem that the image is blurred occurs as described above.
[0010]
In addition, if a method is used in which all four colors of data are used for the trapping process, it is necessary to read out all four colors of data when processing each color, and the facility scale must be increased for transferring a large amount of data. There is.
[0011]
Furthermore, if the trapping process is performed for all the colors in a common manner, there is a problem that an appropriate process corresponding to the characteristics of each color cannot be performed. Specifically, if the same processing is performed on a black character as that for other colors, there is a problem that the character is blurred, the effect of smoothing is reduced, and the character becomes difficult to read.
[0012]
FIG. 7 is a diagram for explaining such a problem. 7A shows the original image, FIG. 7B shows the image when only edge smoothing is performed, and FIG. 7C shows the image when trapping processing and edge smoothing are performed. Represents an image. E in FIG. 7B indicates a portion added by edge smoothing, and F in FIG. 7C indicates a portion added by trapping processing. As is clear from FIG. 7C, when both the trapping process and the edge smoothing are performed, the portion added by the edge smoothing overlaps with the portion added by the trapping process (G in FIG. 7C). , The effect of smoothing disappears.
[0013]
Further, as another example, Y (yellow) has a characteristic that the white spots can be made more inconspicuous by performing strong trapping due to low visibility. There is a problem that processing that can be utilized cannot be performed.
[0014]
Therefore, an object of the present invention is to provide an image processing apparatus that performs image processing on received print data and outputs the data after the image processing to a print engine without causing an increase in apparatus scale and a reduction in processing speed. An object of the present invention is to provide an image processing apparatus capable of performing an effective trapping process.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, one aspect of the present invention is a preprocessing unit that converts received print data into bitmap data and stores it in a memory, and stores the print data in the memory in response to driving of a print engine. A post-processing unit that performs processing on the bitmap data and outputs the processed data to the print engine, wherein the post-processing unit performs a trapping process based on the bitmap data. The processing means is provided. Therefore, according to the present invention, since the trapping process is not performed until the data is converted into the bitmap data, that is, at the stage of the preprocessing described above, the printing speed is not reduced.
[0016]
Further, in the above-mentioned invention, in a preferred aspect, the bitmap data includes data of a plurality of colors, and when the trapping processing unit performs a process on each color, the bitmap data performs the process out of the bitmap data. The processing is performed without referring to data of a color other than the color to be executed. As a result, the data transfer amount can be reduced, so that the trapping process can be executed without increasing the device scale.
[0017]
Further, in the above invention, in a preferred aspect, the bitmap data includes data of a plurality of colors, and when the trapping processing unit executes a process for each color, a predetermined total of the bitmap data is Processing is performed based on data of two or more specific colors less than the colors. This makes it possible to perform more effective trapping processing than when processing is performed based on one-color data, and can reduce the device scale as compared with the case where all-color data is used.
[0018]
Further, in the above invention, another embodiment is characterized in that the bitmap data includes data of a plurality of colors, and the trapping processing unit performs processing for each color, and the bitmap data includes a plurality of colors of the plurality of colors. The process is performed based on data of all colors. According to this aspect, since the state of all colors is considered in the trapping process, more appropriate trapping process can be performed, and effective image quality degradation can be prevented.
[0019]
In a preferred aspect of the above-mentioned invention, the post-processing unit includes a resolution conversion unit, and the trapping processing unit executes the processing after the resolution conversion processing by the resolution conversion unit.
[0020]
In a preferred aspect of the above invention, the post-processing unit includes a pulse width modulation unit that converts pulse width data into an ON / OFF signal of laser emission, and the trapping processing unit includes the pulse width modulation unit. Is provided before the.
[0021]
Furthermore, in the above invention, in a preferred aspect, the post-processing unit includes a screen processing unit that converts the bitmap data into pulse width data, and the trapping processing unit is provided before the screen processing unit. It is characterized by being able to.
[0022]
Further, in the above-mentioned invention, in a preferred aspect, the printing is printing in a plurality of colors, and the trapping processing means is provided for each of the plurality of colors.
[0023]
In a preferred aspect of the present invention, the processing methods of the plurality of trapping processing means for the plurality of colors are not the same. As a result, trapping processing utilizing the characteristics of each color can be performed, and the deterioration of image quality can be more effectively prevented.
[0024]
In order to achieve the above object, another aspect of the present invention is a preprocessing unit that converts received print data into bitmap data and stores the same in a memory, and the memory corresponding to the drive of a tandem print engine. An image processing apparatus comprising: a plurality of post-processing units provided for each color, wherein the post-processing unit outputs a processed data to the tandem-type print engine, and outputs the processed data to the tandem print engine. The processing unit includes: a resolution conversion unit that converts the resolution of the bitmap data; and a trapping processing unit that performs a trapping process based on the bitmap data whose resolution has been converted by the resolution conversion unit. It is. Therefore, according to the present invention, it is possible to effectively prevent the deterioration of image quality without impairing the high-speed performance of the tandem system.
[0025]
Further, in the above invention, a preferable aspect is that the resolution conversion means includes a buffer for storing a predetermined amount of bitmap data after the resolution conversion, and the trapping processing means includes a buffer for storing the bitmap data stored in the buffer. Processing is performed based on the map data. As a result, it is not necessary to provide a new buffer for the trapping processing means, and the size of the apparatus can be reduced.
[0026]
In order to achieve the above object, another aspect of the present invention is a preprocessing unit that converts received print data into bitmap data and stores the same in a memory, and the memory corresponding to the drive of a tandem print engine. An image processing apparatus comprising: a plurality of post-processing units provided for each color, wherein the post-processing unit outputs a processed data to the tandem-type print engine, and outputs the processed data to the tandem print engine. The processing unit, each based on the bitmap data, without referring to data of a color other than the color to be processed, without having a trapping processing means for performing a trapping process to expand the edge of the color to be processed Features. Therefore, according to the present invention, when the trapping process is performed in the tandem system, the device scale can be reduced.
[0027]
Further objects and features of the present invention will become apparent from the embodiments of the present invention described below.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, such embodiments do not limit the technical scope of the present invention. In the drawings, the same or similar components will be described with the same reference numerals or reference symbols.
[0029]
FIG. 1 is a configuration diagram of an image processing apparatus according to a first embodiment of the present invention. The image processing apparatus 2 shown in FIG. 1 is the image processing apparatus according to the first embodiment, and is provided in a tandem-type printer. As shown in the figure, the image processing apparatus 2 includes a pre-processing unit 21, a page memory 22, and a post-processing unit 23. After receiving the print data 1 transmitted from a personal computer or the like, the image processing device 2 , And outputs the processed data to the print engine 3. The image processing apparatus 2 is characterized in that a trapping processing unit 25 (trapping processing means) is provided in a post-processing unit 23 that executes processing at the time of printing, and that a trapping process of each color is performed only with data of the color. It is intended to perform an effective trapping process without increasing the processing speed and reducing the processing speed. Hereinafter, the configuration and processing contents of each unit of the image processing apparatus 2 will be described, focusing on the trapping processing.
[0030]
First, the pre-processing unit 21 shown in FIG. 1 is the same as the conventional device, receives print data 1 expressed in a page description language, and performs processing such as data interpretation, color conversion, and compression on the data. The processed data is stored in the page memory 22. The stored data is converted into data for each pixel, that is, bitmap data, and each pixel has data of four colors of C, M, Y, and K. Note that the data of each color is expressed in 1 byte.
[0031]
The page memory 22 holds this bitmap data for one page of printing. Therefore, the page memory 22 holds C, M, Y, and K data for one page to be printed.
[0032]
Next, the post-processing unit 23 is a part that operates in synchronization with the print engine 3 during printing by the print engine 3. Since the printer in the present embodiment is of a tandem type, the post-processing unit 23 Is provided. Therefore, as shown in FIG. 1, the image processing apparatus 2 includes four types of post-processing units 23C, 23M, 23Y, and 23K. Since the configuration and function of each post-processing unit 23 are the same, a description will be given below of the post-processing unit 23C that processes the data of C.
[0033]
The post-processing unit 23C executes processing in synchronization with the print engine 3 when printing one page of image data stored in the page memory 22 as described above. After performing the processes such as reading of the C data, resolution conversion, trapping, binarization, and the like to make the data printable, the data is output to the print engine 3. Therefore, as shown in FIG. 1, the post-processing unit 23C includes a resolution conversion unit 24 (resolution conversion unit) for executing each of these processes, a trapping processing unit 25, a screen unit 26 (binarization unit), and a pulse width. A combining unit 27 and a PWM unit 28 (pulse width modulation means) are provided.
[0034]
First, when printing at a resolution higher than the bitmap data stored in the page memory 22, the resolution conversion unit 24 is a part that executes processing for converting the resolution to high and processing for smoothing the edge portion. As shown in FIG. 1, the resolution conversion unit 24 includes a timing control unit 241, a raster buffer 242, and a smoothing processing unit 243. The timing control unit 241 is a part that controls the timing at which the data of C is read from the band memory 22. For example, when the resolution is doubled, the timing control unit 241 applies two read signals in both the vertical and horizontal directions. Control to perform one reading. As a result, the pixel density is quadrupled and the data corresponding to the print engine with twice the resolution is sent to the raster buffer 242.
[0035]
The raster buffer 242 holds the C data read from the page memory 22 for each raster (one horizontal line of one page). For example, data for eight rasters is held. This is because, in the smoothing process described below, data around a pixel (region) to be processed is also required.
[0036]
The smoothing processing unit 243 is a unit that performs correction so that a stair-like expression by pixels is canceled as much as possible and a smooth inclined line is displayed, for example, when an edge portion where the color changes is oblique. Specifically, data in a predetermined range around the pixel of interest, for example, data for 8 rasters × 9 pixels, is read from the raster buffer 242, and an edge serving as a color transition is detected. Then, the detected edge shape is compared with a predetermined edge pattern (template), and the correction content is determined based on the matched pattern. The content of the correction is sent to the pulse width synthesizing unit 27 as correction information.
[0037]
Next, the trapping processing unit 25 (trapping processing means) is a characteristic part of the image processing apparatus 2, and is a part that executes a trapping process in a process during printing synchronized with the print engine 3. The trapping processing unit 25 determines, for each pixel in the print range, whether or not the pixel is an edge based on the C data read from the page memory 22, that is, whether or not to perform the trapping process. The determination and the determination of the trap amount, that is, the determination of the pixel value of the pixel are performed. As described above, the feature of the image processing apparatus 2 is that only the C data is used in the trapping processing of the C data.
[0038]
Hereinafter, specific processing contents will be described. First, the trapping processing unit 25 reads out data of a pixel to be processed and its surrounding pixels from the raster buffer 242. For example, when the pixel to be processed is located in the portion shown in FIG. 1A, the data of the target pixel and the left and right and upper and lower pixels are extracted from the raster and the upper and lower raster data included in the portion. read out. This is because surrounding data is needed to determine whether or not to perform trapping on the target pixel. As described above, the buffer for storing the data of the surrounding pixels can be shared with the buffer for the above-described smoothing processing. Therefore, the configuration of the image processing apparatus 2 has an effect that the apparatus scale can be reduced. Have.
[0039]
Next, the trapping processing unit 25 determines whether or not to perform trapping on the target pixel based on the read data. In other words, it is determined whether or not the target pixel is an edge. Various methods can be used as a specific determination method, and an example is shown below.
[0040]
For example, when the pixel value (data value of C, density of C) of the target pixel (pixel of interest) is smaller than a predetermined threshold value, and there is a pixel whose peripheral pixel value is larger than the threshold value among the surrounding pixels Then, the target pixel is regarded as an edge, and a trapping process is performed.
[0041]
FIG. 2 is a diagram illustrating an example of a process performed by the trapping processing unit 25. FIG. 2A shows an example of a pixel value read from the raster buffer 242. A in the figure is a target pixel, and B1 to B4 in the figure are surrounding pixels. Therefore, the pixel value of the target pixel is “50”, and the pixel value of the surrounding pixels located above it is “200”. Here, the results of performing the above-described edge determination on these data are shown in FIGS. 2B and 2C.
[0042]
FIG. 2B shows a case where the threshold value is set to “70”, for example, where “0” in the figure indicates that the pixel value is smaller than the threshold value, and “1” in the figure indicates that the pixel value is Indicates that the value is greater than the threshold. Since the pixel value of the target pixel (A) is smaller than the threshold value “70”, the result of the determination is “0”, and the pixel value of the surrounding pixel (B1) is larger than the threshold value “70”. Is "1". Therefore, in this case, since the pixel value of the target pixel is smaller than the threshold value and there is a pixel whose pixel value is larger than the threshold value in the surrounding pixels, the target pixel is regarded as an edge and the trapping process is performed. Is determined. On the other hand, FIG. 2C shows a case where the threshold value is set to “45”, for example. Since the pixel value of the target pixel (A) is larger than the threshold value “45”, the determination result is “1”. Therefore, it is determined that the above-described condition is not satisfied and the trapping process is not performed.
[0043]
Next, the trapping processing unit 25 performs a process of determining a trap amount, that is, a process of determining a pixel value of a target pixel. When it is determined that trapping is to be performed by the determination as to whether or not to perform the trapping process, a pixel value larger than the original pixel value determined by a predetermined method is given to the target pixel. On the other hand, when it is determined that trapping is not to be performed, the original pixel value is kept.
[0044]
Various methods can be used to determine a pixel value when it is determined that trapping is performed.For example, a smaller value of a predetermined minimum trap value and a maximum pixel value of surrounding pixels, whichever is smaller, A method can be used in which a larger value of a value obtained by multiplying a predetermined trap rate by a maximum pixel value of surrounding pixels is used as a pixel value of a target pixel. Hereinafter, the case where this method is used for the input shown in FIG. 2A will be described. Assuming that the predetermined minimum trap value is “100” and the predetermined trap rate is “0.4”, the smaller of the predetermined minimum trap value and the maximum pixel value of the surrounding pixels is determined. The value becomes “100” by comparing “100” and “200”. Further, a value obtained by multiplying a predetermined trap rate by the maximum pixel value of the surrounding pixels is “80” by multiplying “0.4” by “200”. Therefore, “100” which is the larger value of “100” and “80” is determined as the pixel value of the target pixel. With this determination, the pixel value of the target pixel (A) is replaced with “100”. FIG. 2D shows the result.
[0045]
As described above, when the pixel value of the target pixel is determined, the trapping processing unit 25 sets the determined value as a new pixel value of the target pixel, and transmits the data to the next screen unit 26. The trapping processing unit 25 sequentially executes the above-described processing on the print range for each pixel.
[0046]
As described above, the other three types of post-processing units 23M, 23Y, and 23K provided in the image processing apparatus 2 have the same trapping processing units, respectively. For each of the colors M, Y, and K, Trapping processing is performed using only the data of each color. For example, the trapping processing unit of the post-processing unit 23M executes a trapping process using only the data of M stored in the page memory 22. As described above, since the image processing apparatus 2 includes the trapping processing unit for each color independently, the content of the trapping processing can be changed for each color, and effective trapping according to the characteristics of each color can be performed. is there.
[0047]
For example, for K (black), no trapping process is performed, or the trapping amount is reduced compared to other colors, so that the above-described adverse effect of black characters and the effect of edge smoothing are reduced. Problems can be prevented. In addition, for Y (yellow), by performing processing to increase the trapping amount as compared with other colors, an effect of making the white spots due to misregistration less noticeable can be obtained.
[0048]
When the trapping process as described above is completed, the screen unit 26, the pulse width synthesizing unit 27, and the PWM unit 28 thereafter execute each process in the same manner as in the conventional device, and finally, the printable The data is output to the print engine 3. The screen unit 26 performs a process of converting the pixel value into a pulse width. The pulse width synthesizing unit 27 corrects the pulse width from the screen unit 26 based on the correction information from the smoothing processing unit 243 described above. In the PWM unit 28, the data of the pulse width is converted into an ON / OFF signal for laser emission.
[0049]
As described above, by using the image processing apparatus 2 according to the first embodiment, the trapping process is performed in the post-process performed at the time of printing, so that the speed of the tandem-type printer is not impaired. In addition, it is possible to prevent the image quality from deteriorating due to the displacement. Further, since the data of only the four colors is used in the trapping process of each color without using the data of all four colors, it is not necessary to transfer a large amount of data, and the apparatus scale can be reduced. Furthermore, since each color has an independent trapping processing unit, the content of the trapping processing can be changed for each color, and more effective trapping processing utilizing the characteristics of each color can be performed.
[0050]
Next, a second embodiment of the image processing apparatus to which the present invention is applied will be described. FIG. 3 is a configuration diagram of an image processing apparatus according to the second embodiment. The image processing apparatus 2 ′ according to the second embodiment is characterized in that when performing the trapping process of each color, both the data of the color and the data of K (black) are used. This is the same as the image processing device 2 according to the first embodiment. Therefore, the device configuration is such that a portion for taking the data of K from the page memory 22 into the trapping processing unit is added to the image processing device 2 according to the first embodiment. Therefore, FIG. 3 also illustrates only the periphery of the changed part in the post-processing unit 23C ′ that processes the data of C. Regarding the processing contents, the other parts than the trapping processing unit 25 'are the same as those in the first embodiment, and therefore, only the processing in the trapping processing unit 25' will be described below.
[0051]
Also in the trapping processing unit 25 ′ of the present embodiment, the processing of fetching data from the page memory 22, determining whether or not the trapping processing can be performed, and determining the pixel value are performed for each pixel in the print range. The trapping processing unit 25 'of the post-processing unit 23C' that performs processing on the C data uses the C data and the K data, but the C data is processed by the resolution conversion unit as in the first embodiment. 24, and K data is fetched from the page memory 22. The raster buffer 242 (not shown in FIG. 3). Similar to the C data, the data of the surrounding pixels are required for the K data, and therefore, although not shown, a raster buffer for the K data is provided between the page memory 22 and the trapping processing unit 25 '. .
[0052]
The process of determining whether or not the trapping process can be performed and the process of determining the pixel value are performed in the same flow as in the first embodiment, but both of the captured C and K data are used in these processes. Therefore, even when the data values of C of the target pixel and the surrounding pixels are the same, different trapping processes can be performed if the data values of K are different.
[0053]
FIG. 4 is a diagram for explaining an example. 4A shows an area a1 in which the value of K is “255” and the value of C is “0”, and the value of K is “0” and the value of C is “255”. The figure shows a case where certain areas a2 are adjacent to each other, and the lower figure shows the pixel values (density) of K and C along the straight line 1 in the upper figure. As described above, at the edge of the region a <b> 1 painted black, when white spots occur due to misalignment, the edge is conspicuous. Therefore, trapping more times is effective in preventing image quality deterioration. Therefore, as shown at t1 in FIG. 4A, trapping processing is performed so as to add more colors to the edges of the areas a1 and a2.
[0054]
On the other hand, the upper diagram of FIG. 4B shows an area a1 in which the value of K is “0” and the value of C is also “0”, the value of K is “0”, and the value of C is “255”. "Indicates that the areas a2 adjacent to each other are adjacent to each other, and the lower diagram shows the pixel values (densities) of K and C along the straight line 1 in the upper diagram. In such a case, even if white spots occur, they are less noticeable than in the case of FIG. 4A, so that the trap amount is set to a small value and a color is added as shown at t2 in FIG. 4B. . As described above, even when the state of the data of C is the same, different trapping processes are executed due to the different data of K.
[0055]
As described above, in the image processing device 2 ′ according to the second embodiment, since the data of K is also used for the trapping process of each color, a more appropriate and effective trapping process can be performed. It is possible to further prevent the image quality from deteriorating as compared with the embodiment. In the present embodiment, the data of K is used in the trapping process of each color in addition to the data of the color. However, data other than K may be used. Color data may be used. For example, the data of M and K may be used in the trapping process of C in addition to the data of C.
[0056]
Next, a third embodiment of the image processing apparatus to which the present invention is applied will be described. FIG. 5 is a configuration diagram of an image processing apparatus according to the third embodiment. The image processing apparatus 2 ″ according to the third embodiment is characterized in that data of all four colors is used when performing the trapping processing of each color. This is the same as the image processing device according to the embodiment. Therefore, as shown in FIG. 5, the image processing apparatus 2 according to the first embodiment also has a configuration in which the three-color data other than the color to be processed is loaded from the page memory 22 into the trapping processing unit. It has been added. Regarding the processing contents, parts other than the trapping processing unit 25 '' are the same as those in the first embodiment.
[0057]
The same applies to the post-processing units of other colors, but the trapping processing unit 25 '' of the post-processing unit 23C '' for C shown in FIG. The color (M, Y, K) data is fetched from the page memory 22. As with the C data, the data of the surrounding pixels is required for the three colors of data. Therefore, although not shown, a raster buffer for this is provided between the page memory 22 and the trapping processing unit 25 ''. Can be After capturing the data, the trapping processing unit 25 ″ performs the determination of whether or not to perform the trapping process and the determination of the pixel value in the same flow as in the first embodiment. Color data is used.
[0058]
As described above, in the image processing apparatus 2 ″ according to the third embodiment, since data of all four colors is used for the trapping process of each color, the data transfer amount is large and is larger than that of the first embodiment. Although the scale of the apparatus is increased, more accurate and effective trapping can be performed, and the deterioration of the image quality due to the displacement can be further prevented.
[0059]
In the first to third embodiments described above, the image processing apparatus is a tandem-type printer that performs four-color processing in parallel. However, the present invention performs the processing in order for each color. The present invention can also be applied to an image processing apparatus in a four-cycle printer. In such a case, a post-processing unit similar to the post-processing unit 23 illustrated in FIGS. 1, 3, and 5 is provided, and the trapping process is performed on the C, M, Y, and K data in order. Each process including the above is executed with the same contents as those of the above-described embodiment.
[0060]
The protection scope of the present invention is not limited to the above embodiments, but extends to the inventions described in the claims and their equivalents.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an image processing apparatus according to a first embodiment.
FIG. 2 is a diagram illustrating an example of a process performed by a trapping processing unit 25;
FIG. 3 is a configuration diagram of an image processing apparatus according to a second embodiment.
FIG. 4 is a diagram illustrating an example of a trapping process according to a second embodiment;
FIG. 5 is a configuration diagram of an image processing apparatus according to a third embodiment.
FIG. 6 is a diagram for explaining a problem of a trapping process.
FIG. 7 is a diagram for explaining a problem of a trapping process.
[Explanation of symbols]
1 print data, 2 image processing device, 3 print engine, 21 pre-processing unit, 22 page memory, 23C, 23M, 23Y, 23K post-processing unit, 24 resolution conversion unit, 25 trapping processing unit, 26 screen unit, 27 pulse width Synthesis unit, 28 PWM unit, 241 timing control unit, 242 raster buffer, 243 smoothing processing unit

Claims (12)

A preprocessing unit that converts received print data into bitmap data and stores the bitmap data in a memory; and performs processing on the bitmap data stored in the memory in response to driving of the print engine, and stores the processed data in the print engine. An image processing apparatus having a post-processing unit that outputs
The image processing apparatus according to claim 1, wherein the post-processing unit includes a trapping unit that performs a trapping process based on the bitmap data. In claim 1,
The bitmap data includes data of a plurality of colors,
An image processing apparatus wherein, when the trapping processing unit performs a process for each color, the trapping processing unit performs the process without referring to data of a color other than the color to be processed in the bitmap data. . In claim 1,
The bitmap data includes data of a plurality of colors,
When the trapping processing means executes processing for each color, the trapping processing means executes processing based on data of two or more specific colors smaller than all predetermined colors in the bitmap data. Image processing device. In claim 1,
The bitmap data includes data of a plurality of colors,
The image processing apparatus according to claim 1, wherein the trapping processing unit executes processing based on data of all of the plurality of colors in the bitmap data when executing processing for each color. In any one of claims 1 to 4,
The post-processing unit includes a resolution conversion unit,
An image processing apparatus, wherein the trapping processing means executes processing after the resolution conversion processing by the resolution conversion means. In any one of claims 1 to 5,
The post-processing unit includes a pulse width modulation unit that converts pulse width data into an ON / OFF signal of laser emission;
An image processing apparatus according to claim 1, wherein said trapping processing means is provided before said pulse width modulation means. In any one of claims 1 to 6,
The post-processing unit includes a screen processing unit that converts the bitmap data into pulse width data,
An image processing apparatus, wherein the trapping processing means is provided before the screen processing means. In any one of claims 1 to 7,
The printing is printing by a plurality of colors,
An image processing apparatus, wherein the trapping processing means is provided for each of the plurality of colors. In claim 8,
An image processing apparatus, wherein processing methods of the plurality of trapping processing units for the plurality of colors are not the same. A preprocessing unit that converts the received print data into bitmap data and stores it in a memory, and performs processing on the bitmap data stored in the memory in response to the driving of the tandem print engine, and processes the processed data. An image processing apparatus that outputs to a tandem print engine and has a plurality of post-processing units provided for each color,
The post-processing units of the respective colors are respectively
Resolution conversion means for converting the resolution of the bitmap data,
An image processing apparatus comprising: a trapping processing unit that performs a trapping process based on bitmap data whose resolution has been converted by the resolution conversion unit. In claim 10,
The resolution conversion means, after the resolution conversion, comprises a buffer for holding a predetermined amount of bitmap data,
An image processing apparatus, wherein the trapping processing means executes a process based on the bitmap data held in the buffer. A preprocessing unit that converts the received print data into bitmap data and stores it in a memory, and performs processing on the bitmap data stored in the memory in response to the driving of the tandem print engine, and processes the processed data. An image processing apparatus that outputs to a tandem print engine and has a plurality of post-processing units provided for each color,
An image characterized in that each of the post-processing units of the respective colors includes a trapping processing unit that executes the trapping process based on the bitmap data without referring to data of a color other than the color to be processed. Processing equipment.

Images