JP2017103563A - Image processing apparatus and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To output data capable of efficiently executing a synthesis processing of a pixel in a region where a plurality of objects is overlapped in a simple structure.SOLUTION: An image processing apparatus that converts data indicating an image of a print target into raster image data, includes: first holding means of holding at least a part of image information of an object drawn in a continuous pixel in a processing target line in the image; second holding means of holding pixel information of the object formed by a single pixel value in the continuous pixel; input means of inputting the pixel information of the continuous pixel to the first or second holding means in each layer corresponding to the object; and output means of specifying a region that can be commonly processed on the basis of the pixel information in the continuous pixel, and outputting the pixel information from the first or second holding means as one pair of the pixel information of a whole layer in the region.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for generating image data from data described in a page description language (PDL).

  When printing an image on a recording medium, print target data described in a page description language (PDL) is received via a communication medium such as a network. For output by an image forming apparatus such as a printer, data described in PDL is converted into raster image data by executing RIP (Raster Image Processor) processing on the data described in PDL. Specifically, first, an interpreter dedicated to the image forming apparatus (printer) to print interprets the data described by the received PDL, and creates intermediate data based on whether or not the interpretation is performed. Further, a rendering process is executed based on the intermediate data to generate a raster image wp. The raster image generated by the RIP processing as described above is subjected to predetermined image processing, converted into print data that can be printed by the sub-g image forming apparatus, and the printer prints on the recording medium based on the print data. .

  Furthermore, a scan line algorithm is known for rendering processing. In the scan line algorithm, the intersection between the boundary (edge) of the object to be drawn and the scan line is calculated, and the pixel value of the continuous pixel (span) between two adjacent edges is calculated from the object information. If opaque objects overlap, the final result can be obtained by drawing only the foreground object by determining the overlap of the objects in span units.

  On the other hand, when transparent objects overlap, in order to calculate the final pixel value, it is necessary to combine the pixel values of all the transparent objects in the overlapping order. However, in the scan line algorithm, it is necessary to determine the overlap of objects for each span and perform a process of combining them. Therefore, in the case of data in which many transparent objects are overlapped, the processing becomes complicated and takes time.

  Therefore, in Patent Document 1, the resolution information of two overlapping objects is acquired, and a low-resolution object is converted and combined with a high-resolution object at the time of image composition, thereby compositing at a resolution lower than the output resolution as much as possible. .

JP 2009-130465 A

  In the method disclosed in Patent Document 1, complicated control is required to synthesize pixels in a region where three or more objects overlap. Furthermore, in order to synthesize pixels, it is necessary to wait for the pixel information in each layer to be output in the order in which the objects overlap.

  Accordingly, an object of the present invention is to output data that can efficiently combine pixels in a region where a plurality of objects overlap with a simple configuration.

  In order to solve the above-described problem, an image processing apparatus that converts data representing an image to be printed into raster image data, and is continuous based on the number of objects to be drawn overlapped on the processing target line in the image. Acquisition means for acquiring pixel position information; first holding means for holding pixel information indicating at least a part of pixel data of the drawn object in the continuous pixels; and Among the continuous pixels, a second holding unit that holds pixel information indicating pixel data of an object having a single pixel value in the continuous pixels and the continuous pixels for each layer corresponding to the object. The first holding means or the second holding means using pixel data of pixels as pixel information in the overlapping order of the objects Based on the pixel information in the continuous pixels held in the first holding means or the second holding means, the common processing area is specified based on the input means that inputs to the stage, and in the area It has an output means for taking out and outputting the pixel information of all layers as one set from the first holding means or the second holding means.

  According to the present invention, it is possible to output data that can efficiently combine pixels in a region where a plurality of objects overlap with a simple configuration.

1 is a block diagram illustrating an example of the overall configuration of an image forming apparatus according to a first embodiment. The block diagram which shows the structural example of the renderer process part 106 of a conventional structure. The figure which shows an example of the printing data with which the object overlapped over several layers. The figure which shows the pixel information command example and generation order of the several layers of the span 4 of FIG. FIG. 4 is a diagram illustrating an example of a span and a pixel information command when a plurality of layers of the span 4 in FIG. 3 are divided into spans in units of pixels. The block diagram which shows the structural example of the renderer process part 106 in 1st Embodiment. FIG. 3 is a block diagram illustrating a configuration example of a pixel buffer 601. FIG. 6 is a processing flowchart of the output control unit 703 in the pixel buffer 601. FIG. 3 is a block diagram illustrating a configuration example of a pixel buffer 601 according to the first embodiment. The processing flowchart of the output control part 904 in 1st Embodiment. The figure which shows the process example of the pixel buffer 601 in 1st Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

<First Embodiment>
FIG. 1 is a block diagram illustrating an example of the overall configuration of an image forming apparatus 100 applicable to the first embodiment. The image forming apparatus 100 includes a CPU 101, a ROM 102, a RAM 103, an input unit 104, a PDL processing unit 105, a renderer processing unit 106, an image processing unit 107, and an output unit 108, which are connected via a shared bus 109.

  The CPU 101 reads and executes a control program stored in the ROM 102 to comprehensively control arithmetic processing and operations of each unit of the image forming apparatus 100. The RAM 103 is a readable / writable memory and is a storage medium for temporarily storing various data such as image data. The input unit 104 receives data to be printed (hereinafter referred to as PDL data) described in a page description language transferred from a host PC or server (not shown), and stores it in the RAM 103. The PDL processing unit 105 analyzes the PDL data received by the input unit 104 and converts it into intermediate data in a format that can be interpreted by the renderer processing unit 106. The renderer processing unit 106 generates raster image data from the intermediate data generated by the PDL processing unit 105. The image processing unit 107 performs predetermined image processing on the raster image data generated by the renderer processing unit 106 to generate print data. The output unit 108 is an inkjet head or a laser beam type printer engine, and executes print processing according to print data generated via the image processing unit 107.

  FIG. 2 is a block diagram showing a conventional renderer processing unit 106. Problems in the conventional renderer processing unit 106 will be described. The renderer processing unit 106 includes an instruction execution unit 201, an edge processing unit 202, a pixel generation unit 203, a pixel synthesis unit 204, a pixel synthesis stack 205, and a pixel output unit 206, and executes pipeline processing. The instruction execution unit 201 reads and processes the processing instruction 208 from the intermediate data 207, and transfers the read instruction as a command to each processing unit. The edge processing unit 202 reads edge information 209 from the intermediate data 207, and generates position information of continuous pixels (spans) between two intersections where the scan line and the object outline intersect. Each span is a line segment composed of a group of pixels having the same layer overlap corresponding to the object. Further, the edge generation unit 202 transfers span position information for generating pixels to the pixel generation unit 203 as a span information command. The span information command generated here is also transferred to each processing unit of the pipeline. The pixel generation unit 203 refers to the pixel data table 210 of the intermediate data 207 and generates pixel information in the span from the span information command. When it is necessary to synthesize the overlap of multiple objects in order to determine the final output pixel value in the received span, the pixel synthesizer 204 uses the pixel synthesize stack 205 to synthesize the pixel halfway. Hold intermediate results. The pixel output unit 206 outputs the final pixel value calculated by the pixel composition unit 204 to an output buffer (not shown) as a rendering result.

  Next, processing when a plurality of objects overlap in the same span will be described. FIG. 3 shows an example of a page in which three objects of the image object 301 and the single color fill objects 302 and 303 overlap. The image object 301 is an opaque object drawn on the backmost layer 1 and invisible on the back. Objects 302 and 303 are drawn on layer 2 and layer 3, respectively, and overlap the front surface of the image object 301. It is assumed that layers 1, 2, and 3 overlap from the back to the front. Further, the objects 302 and 303 are transparent objects that can be seen through the back. Therefore, for the region where the objects 302 and 303 overlap, in order to generate the final output value of the pixels included in the region, it is necessary to synthesize the pixel values of the respective objects.

  The generation of the span of the scan line 304 that crosses the position where the three objects overlap as described above and the rendering of the span will be described. A scan line 304 that is a processing target line is processed by being divided into a plurality of spans according to intersections with the outlines of the objects. As shown in FIG. 3, the scan line 304 is divided into seven spans, span 1 to span 7. The start position and end position of each span are set in advance by the PDL processing unit 105, and are encoded and stored as edge information 209 of the intermediate data 207. The edge information 209 is decoded by the edge processing unit 202 of the renderer processing unit 105, whereby the start position and end position of each span are calculated. In the edge information 209, a reference destination of pixel information drawn in each span is registered. When a plurality of objects are drawn with overlapping on the same span, a plurality of reference destinations are registered in order from the backmost layer. For example, in span 4, since three objects overlap, the reference destinations of the pixel information of the image object 301 and the objects 302 and 303 are registered in order from the back. In the pipeline processing in the renderer processing unit 105, the reference destination information is transmitted from the edge processing unit 202 to the pixel generation unit 203 as a span information command including the position information of the span 4.

  In this way, since the span information command has the information of the reference destination, one span information command is generated for each layer having the object to be drawn. That is, a plurality of span information commands are generated in a span where a plurality of objects overlap. The span information command has a flag indicating whether or not the corresponding layer is the highest layer. The pixel generation unit 203 generates pixel data of each object by referring to the intermediate data 207 from the received span position information and pixel information reference destination information, and transmits the generated pixel data to the pixel synthesis unit 204 as a pixel information command. At this time, the pixel generation unit 203 sends a plurality of pixels having the same pixel value to the pixel composition unit 204 as one pixel information command. The pixel information command includes information on the generated pixel value and its start pixel position and end pixel position. Since the pixel generation unit 203 sends the same pixel sequence as one message, pixel information as shown in FIG. 4 is sent to the pixel synthesis unit 204 in the example of span 4 in FIG. FIG. 4 shows an example of pixel information commands sent as the pixel information of span 4 in FIG. 3 and the generation order thereof. The pixel generation unit 203 refers to the intermediate data, and generates pixels from the start position to the end position of the specified object in the overlapping order. Therefore, the pixel information of the upper layer is not generated until all the pixel information of the lower layer is generated as in the generation order shown in FIG.

  The pixel synthesizing unit 204 receives the pixel information commands sent in the order as described above, appropriately synthesizes the pixel data of each object located in the overlap of a plurality of layers, and determines the final output value of each pixel To do. For example, in the example of FIG. 4, unless all the four pixel information of layer 1 is saved, it cannot be appropriately combined with the pixel of layer 2. Further, depending on the object drawing method, the pixel information of layer 1 is temporarily stored, the pixels of layer 2 and layer 3 are combined, and the combined pixel is combined with layer 1. In order to temporarily store the pixel information, the pixel composition stack 206 is used. Thus, in the conventional configuration, since the pixel information is sent in the order as described above, it is necessary to buffer the pixel information of all objects drawn in the span, which requires a lot of resources. . Further, since the pixel synthesis unit 204 needs to process pixel information with different pixel ranges in which the same number of pixels continues for each layer as shown in FIG. 4, complicated control is required.

  On the other hand, as a conventional technique for reducing the resources required for the pixel composition stack 206, there is known a technique of processing by dividing into spans of pixel units as shown in FIG. Yes. In this way, if the span, which is a unit for generating pixel information, is further divided and pixels are generated in accordance with the order of pixel composition, it is not necessary to buffer all the pixels of the span for pixel composition. However, there has been a problem that the number of span information and pixel information commands that convey the pipeline and the number of times of synthesis increase.

  FIG. 6 shows a configuration of the renderer processing unit 106 applicable to the first embodiment. In contrast to the conventional renderer processing unit 106 shown in FIG. 2, in the renderer processing unit 106 in the first embodiment, a pixel buffer 601 is provided between the pixel generation unit 203 and the pixel synthesis unit 204. The pixel buffer 601 holds the pixel information generated by the pixel generation unit 203 and regenerates the pixel information in a processing flow described later so that the pixel combining unit 204 can efficiently combine the pixel information. Since the first to third layer buffers are configured here, up to three overlaps can be handled. Hereinafter, a configuration example and operation of the pixel buffer 601 will be described. The capacity of each layer buffer 702 is set based on the span length and the number of bits that the object can hold. For example, it is assumed that the maximum number of pixels constituting a span is set to 64 pixels, and image data of up to 8 bits for each of RGB is drawn as an object. In this case, a maximum of 24 bits × 64 pixels of data is stored in one layer buffer 702. Therefore, it is desirable that the layer buffer 702 has a capacity capable of storing data of up to 24 bits × 64 pixels.

  FIG. 7 is a block diagram showing a detailed configuration of the pixel buffer 601 in FIG. The pixel buffer 601 includes an input control unit 701, a layer buffer 702 for buffering pixel information for each layer in the scan direction, and an output control unit 703. When receiving a span information command from the pixel generation unit 203, the input control unit 701 acquires a start pixel position STARTX and an end pixel position ENDX of the span. In addition, by counting the number of span information commands received before receiving a layer having a flag indicating the highest layer included in the span information command, the total number of layers N (in this embodiment, N is 1 to 3). ) To get. The received span information command is transferred to the output control unit. When the pixel information of the span is received from the pixel generation unit 203 following the span information command, the pixel information of the layer sent first is stored in the buffer of the first layer. When all the pixel information of the first layer is stored in the buffer, the number of layers already stored and the total number N of layers are compared, and it is determined whether there are still layers remaining. If there are still layers remaining, the pixel information sent subsequently is stored in the buffer for the second and subsequent layers, and the processing is repeated until the storage for the N layers is completed. When all layers have been saved, the next span information command is received and the same processing is repeated.

  The output control unit 703 extracts pixel information from each layer buffer and regenerates the pixel information so that the pixel combining unit 204 can efficiently combine the pixel information. Hereinafter, the operation of the output control unit 703 will be described with reference to FIG. FIG. 8 is a flowchart of processing executed by the output control unit 703.

  In step S <b> 802, when the output control unit 703 receives a plurality of span information commands from the input control unit 701, the output control unit 703 acquires a start pixel position STARTX and an end pixel position ENDX of the span from the command. Similarly to the input control unit 701, the total number N of layers is obtained by counting the number of span information commands received until a layer having a flag indicating the highest layer included in the span information command is received.

  In step S <b> 802, the output control unit 703 extracts a total of N pieces of pixel information one by one from each of the N layer buffers, and specifies pixel sections that can be extracted in common. The pixel section that can be extracted in common here can be said to be an area (section) that can be processed in common by the pixel synthesis unit 204 in the subsequent stage. The start pixel position of the pixel section to be extracted first is always STARTX, and the end pixel position of the pixel section is obtained by detecting the minimum end pixel position NEXTEND from the consecutive pixel sections of N identical pixels. The start pixel position from the second section is NEXTEND + 1 one section before.

  In step S803, partial pixel information from the start pixel position STARTX to the end pixel position NEXTTX is generated in the order from the first layer to the Nth layer among the N pieces of pixel information extracted in step S801. The generated partial pixel information is output to the pixel composition unit 204 as a set of pixel information. If the NEXTTX pixel position that has already been output up to step S803 has reached the span end position ENDX (NEXTX == ENDX), the current span output processing is terminated, and the next span information command is sent from the input control unit 701. Accept and repeat the same process. If NEXTTX has not yet reached ENDX (NEXTTX <ENDX), the process proceeds to step S804, and the pixel range already transmitted to the pixel composition unit 204 in S803 is deleted from the pixel information of the N layers. As a result of deleting the pixel range in step S804, if there is a layer from which all the pixel ranges are deleted, the process proceeds to step S805. The pixel information of the next pixel range is extracted from the layer buffer of the layer deleted in step S805, the pixel information of the N layers is newly updated, and the processing from S802 is repeated.

  As described above, the pixel information at the position where the object overlaps over a plurality of layers created by the pixel generation unit 203 is buffered. Furthermore, the pixel information of each layer is rearranged and regenerated while aligning the region where the same pixels are continuous between the plurality of layers. As a result, the pixel composition unit 204 can perform composition processing by combining pixel information from layer 1 to layer N as a set in a pixel range in which the composition result of a plurality of pixels is the same across a plurality of layers. Therefore, the pixel synthesizing unit 204 can efficiently execute the pixel synthesizing process without waiting for all pixel information to be transferred in the overlapping order in the span determined by the number of layers. Note that FIG. 6 shows an example in which buffers for three layers are provided, but it is possible to easily cope with four or more arbitrary N layers by changing the number of layer buffers.

<Modification>
In the first implementation expectation, as described with reference to the flowcharts of FIGS. 7 and 8, the pixel information of the overlapped objects is stored in different pixel buffers for each layer. However, in the configuration shown in the first embodiment, it is not possible to process a span where the number of layers overlaps more than the number of layer buffers provided. Therefore, as a modification, a method of providing a single pixel value layer buffer 903 as shown in FIG. 9 will be described. Hereinafter, the operation of the processing in the modification will be described with reference to FIG. 9 and FIG. 10 showing a processing flowchart executed by the output control unit 904. The single pixel value layer buffer 903 is used as a buffer for storing a layer in which the entire area from the start pixel position to the end pixel position of the span is a single pixel value. For example, since the objects 302 and 303 illustrated in FIG. 3 are drawn with a single pixel value regardless of the pixel position, the span generated from these objects is stored in the single pixel value layer buffer 903. To do. Therefore, pixel information of some layers among the pixel information of all layers is input to the layer buffer 902. In the case of an object consisting of a single pixel value, it is not necessary to hold pixel information for each pixel, and it is sufficient to hold pixel information for one pixel. Therefore, for example, similarly to the layer buffer 702 described above, when the same pixel value layer buffer 903 is provided with a capacity capable of storing data of 24 bits × 64 pixels, pixel information of 64 objects can be held. Accordingly, in the case of the buffer shown in FIG. 9, two overlapping image objects that are not single pixel values and up to 64 overlapping object objects consisting of single pixel values can be handled.

  When the input control unit 901 receives a span information command from the pixel generation unit 203, the input control unit 901 acquires the start pixel position STARTX, the end pixel position ENDX, and the total number N of layers of the span, and transfers them to the output control unit. When the pixel information of the span is received from the pixel generation unit 203 following the span information command, it is determined whether or not the processing target layer is a layer composed of an object having a single pixel value. The start pixel position obtained from the pixel information and STARTX, and the end pixel position and ENDX are compared, and the layer of pixel information that coincides with each other is determined as a single pixel layer. If it is a single pixel value layer, the pixel information is stored in the single pixel value layer buffer 903, and the process proceeds to input processing of the next layer. If it is not a single pixel value layer, all the pixel information of this layer is stored in the nth layer buffer [n = 1, 2,..., N: n is a layer that is not the nth single pixel value in the span. To the next layer input processing. The number of layers already stored and the total number N of layers are compared, and if there are still layers, the above process is repeated for the pixel information sent subsequently. When all layers have been saved, the next span information command is accepted and the same processing is repeated.

  The output control unit 904 extracts pixel information from each layer buffer according to the processing flow of FIG. 10 and regenerates the pixel information so that the pixel combining unit 204 can efficiently combine them. Hereinafter, the operation of the output control unit 904 will be described with reference to FIG.

  In step S1001, when the output control unit 904 receives a span information command from the input control unit 901, the output control unit 904 acquires the start pixel position STARTX and the end pixel position ENDX of the span from the command. Further, the total number N of layers is obtained by counting the number of span information commands received until a layer having a flag indicating the highest layer included in the span information command is received.

  In step S1002, the output control unit 904 determines whether each layer is a layer buffer or a single pixel value layer buffer based on the reference destination information used by the pixel generation unit 203 during pixel generation, which is included in the span information command. Detect if it is included. As a result, it is possible to determine from which buffer the pixel information of the Nth layer from the lowest layer should be extracted. In step S1003, when N pieces of pixel information are extracted from the respective buffers based on the determination result in step 1002, pixel sections that can be extracted in common are specified as in the first embodiment. The start pixel position of the pixel section to be extracted first is always STARTX, and the end pixel position of the pixel section is obtained by examining the minimum end pixel position NEXTEND from consecutive pixel sections of N identical pixels. The start pixel position from the second section is NEXTEND + 1 one section before.

  In step S1004, partial pixel information of the start pixel position STARTX and the end pixel position NEXTTX is generated in the order from the first layer to the Nth layer from the N pieces of pixel information extracted in step S1003. The generated partial pixel information is output to the pixel composition unit 204 as a set of pixel information. If the NEXTTX pixel position that has already been output up to step S1004 has reached the span end position ENDX (NEXTX == ENDX), the current span output processing is terminated, and the next span information command is sent from the input control unit 901. Accept and repeat the same process. If NEXTTX has not yet reached ENDX (NEXTTX <ENDX), the process proceeds to step S1005. In step S1005, the pixel range already transmitted to the pixel composition unit 204 in S1004 is deleted from the pixel information of the N layers. As a result of deleting the pixel range in step S1004, when there is a layer from which all the pixel ranges are deleted, the process proceeds to step S1006. The pixel information of the next pixel range is extracted from the layer buffer of the layer deleted in step S1006, the pixel information of N layers is newly updated, and the processing from S1003 is repeated.

  FIG. 11 shows an example of processing a span in which five layers overlap each other with respect to the three kinds of layer buffers of FIG. The main operation of the pixel buffer 601 will be described in detail. The input control unit 901 buffers layer 1 pixel information in the first layer buffer, layer 4 pixel information in the second layer buffer, and layer 2, 3, and 5 pixel information in the single pixel value layer buffer 903. Is done. The output control unit 904 extracts the top pixel information of all five layers from each buffer, and detects the minimum end pixel position. The partial pixel information is transmitted to the pixel synthesizing unit 204 in the overlapping order based on the detected pixel range common to all five layers. Of the extracted pixel information, the transmitted pixel range is deleted. If there is a layer from which all pixel ranges are deleted, new pixel information is extracted from the layer buffer in which the deleted layer is stored. The above processing is repeated until the end pixel position ENDX of the span is reached.

  As described above, according to the modification, the pixel information overlapped over a plurality of layers created by the pixel generation unit 203 is buffered by the pixel buffer 601. Furthermore, the pixel information is rearranged and regenerated while aligning regions where the same pixels are continuous between the plurality of layers. Accordingly, the pixel composition unit 204 can complete the pixel range in which the composition result of the plurality of pixels is the same across the plurality of layers by one set of composition processing from the layer 1 to the layer N, and efficiently perform the pixel composition processing. I can do it. In addition, by providing the single pixel value layer buffer 903 in the pixel buffer 601, it is possible to buffer more layers with less resources. In one page of data, a large number of images such as the object 301 are rarely drawn. On the other hand, there may be a case where a plurality of graphics and layouts having a single pixel value such as the objects 302 and 303 are drawn. Further, as described above, an object composed of a single pixel value may store pixel information for one pixel of an image object, and therefore an object composed of a single pixel value is stored in one buffer. As a result, it is possible to realize a configuration that can handle a larger number of overlaps in one page. In FIG. 9, the configuration has been described with two layer buffers 902 and one single pixel value layer buffer 903, but the number of each buffer can be changed.

Second Embodiment
In the modification of the first embodiment, the input control unit 901 controls whether to buffer in the layer buffer 902 or the single pixel value layer buffer 903 based on the pixel information generated by the pixel generation unit 203. did. In the second embodiment, a description will be given of a method in which the buffer to be buffered is controlled by the edge processing unit 202 and the pixel generation unit 203 that are positioned upstream of the pixel buffer 601 in the pipeline.

  A case where control is performed by the edge processing unit 202 will be described. As described in the first embodiment, the edge processing unit 202 generates a span information command for each layer and transmits the span information command to a module in the subsequent stage of the pipeline. The span information command includes reference destination information for the pixel generation unit 203 to generate pixel information. When the reference destination is a single pixel value, the edge processing unit 202 assigns a flag for notifying that it is a single pixel value to the span information command. When the input control unit 901 detects the flag added to the span information command, the input control unit 901 buffers the pixel information of the corresponding layer in the single pixel value layer buffer. The pixel generation unit 203 may perform the process of providing a flag for notifying that the pixel value is a single pixel value. According to the present embodiment, the input control unit 901 can control the buffer only by detecting the flag of the span information command without analyzing the contents of the pixel information. Similarly, the input control unit 901 may be configured to determine whether the pixel value is a single pixel value from the reference destination information included in the span information command.

<Other embodiments>
In the first embodiment, the operation flow of the output control unit 904 has been described based on the control flow of the pixel buffer 601 before optimization. However, in the present embodiment, it is known in advance that all pixel sections have the same pixel value for the pixel information of the layer stored in the single pixel value layer buffer. Therefore, an optimal mounting form such as excluding the pixel information of the same pixel value layer from the processing target in steps S1003 and S1006 may be adopted.

  Further, the layer buffer 902 and the single pixel value layer buffer 903 may be configured as buffers having the same configuration, and the functions may be switched. That is, a single pixel value layer buffer may be used as a layer buffer in a span where no single pixel value layer exists. In this case, it is determined whether or not there is a single pixel value layer, and the first embodiment and the prejudice example are switched according to the determination result.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 106 Renderer processing part 601 Pixel buffer 701 Input control part 702 1-N layer buffer 703 Output control part

Claims (8)

An image processing apparatus that converts data representing an image to be printed into raster image data,
Acquisition means for acquiring position information of successive pixels based on the number of objects to be drawn overlapping in the processing target line in the image;
First holding means for holding pixel information indicating at least some pixel data of the drawn object in the continuous pixels;
Second holding means for holding pixel information indicating pixel data of an object having a single pixel value in the continuous pixels among the drawn objects;
An input unit that inputs pixel data of the continuous pixels as pixel information to the first holding unit or the second holding unit in the overlapping order of the objects for each layer corresponding to the object among the continuous pixels. ,
Based on the pixel information in the continuous pixels held in the first holding means or the second holding means, a region that can be processed in common is specified, and pixel information of all layers in the region is set to 1 An image processing apparatus comprising output means for taking out and outputting from the first holding means or the second holding means as a set.   When the input unit determines that the layer to which the pixel information belongs is a layer having a single pixel value, the input unit inputs the pixel information to the second holding unit, and the layer to which the pixel information belongs is single. The image processing apparatus according to claim 1, wherein the pixel information is input to the first holding unit when it is determined that the layer does not have a pixel value.   The image processing apparatus according to claim 1, wherein the output unit specifies a plurality of the regions in the continuous pixels. Furthermore, based on pixel information obtained from the output means, there is a determination means for determining a pixel value of each pixel in the processing target line,
The image processing apparatus according to claim 1, wherein the determination unit sequentially determines pixel values with reference to the pixel information for each region.   5. The image processing apparatus according to claim 1, wherein the output unit outputs pixel information in the region in an overlapping order of the layers. 6.   The output means detects the number of layers for each successive pixel in the processing target line and a holding means for holding the pixel information based on a span information command generated for each layer. The image processing apparatus according to any one of claims 1 to 5.   The said 2nd holding | maintenance means functions as said 1st holding | maintenance means, when the layer which has a single pixel value in the said continuous pixel does not exist. The image processing apparatus according to item. An image processing method for converting data representing an image to be printed into raster image data,
In the processing target line in the image, based on the number of overlapping objects to be drawn, obtain the position information of consecutive pixels,
Among the continuous pixels, for each layer corresponding to the object, at least some of the drawn objects in the continuous pixels in the overlapping order of the objects using pixel data of the continuous pixels as pixel information. A first holding unit for holding pixel information indicating data, and a second holding for holding pixel information indicating pixel data of an object having a single pixel value in the consecutive pixels among the drawn objects. Enter into any of the means,
Based on the pixel information in the continuous pixels held in the first holding means or the second holding means, a region that can be processed in common is specified, and pixel information of all layers in the region is set to 1 An image processing method comprising: taking out and outputting from the first holding unit or the second holding unit as a set.

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