JP2006103045A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of attempting speedup of a processing without lowering quality of an image to image data with a large amount of data and a high resolution. <P>SOLUTION: The image forming apparatus which develops the image data of an object unit to drawing data of a pixel unit, and performs image forming based on the drawing data, has a developing means which develops the image data to the drawing data with a first resolution or the drawing data with a second resolution and holds them, and a synthesizing means which synthesizes the drawing data with the first resolution and the drawing data with the second resolution held. The drawing data with the first resolution contains discriminating information for indicating whether the drawing data with the first resolution or the drawing data with the second resolution are preferentially used when the synthetic processing is performed, and the synthesizing means performs the synthetic processing based on the discriminating information. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a printer, and more particularly to an image forming apparatus capable of performing processing for generating pixel-unit image data from input object-unit image data at high speed.

  2. Description of the Related Art Conventionally, an image forming apparatus such as a printer that performs image processing on input image data to generate predetermined image data and forms an image based on the generated image data has been used. In recent years, in order to obtain an output image with higher quality, the resolution of the image data and the gradation of the color density have been increased, and the amount of data processed by the image forming apparatus has increased. For example, compared to handling 600 dpi (dot per inch) image data, when handling 1200 dpi image data, the amount of data to be processed simply becomes four times.

  If the amount of data to be processed increases in this way, it is necessary to increase the memory capacity for storing the data, and the number of accesses to the memory also increases, so that the processing speed naturally decreases. Become.

Therefore, in the following Patent Document 1, as a method for reducing the data amount, when input image data is a multi-value image and logical drawing processing is required, RGB (red, green, blue) 24-bit data is reduced to 8 bits. Then, it is introduced that high-speed processing can be performed in a small memory space by expanding into an 8-bit memory and then performing color conversion and the like.
Japanese Patent Laid-Open No. 11-179968

  However, in the method of Patent Document 1, since the number of bits (the number of gradations) of image data is reduced and color conversion or the like is performed thereafter, the processing speed can be increased, but complete color information is stored. There is a drawback that faithful color reproduction is not possible because it does not have.

  If processing is performed with high resolution and high gradation data, high quality output can be obtained. However, unless the scale of the apparatus is increased and the performance is improved, the processing speed is reduced. In particular, in the process of developing object-unit image data into pixel-by-pixel data, the number of accesses to the memory increases, which is a major factor in reducing the processing speed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of increasing the processing speed of high-resolution image data having a large amount of data without degrading image quality.

  In order to achieve the above object, according to one aspect of the present invention, there is provided an image forming apparatus that develops image data in object units into drawing data in pixel units and forms an image based on the drawing data. Depending on the type, the image data is expanded into the drawing data of the first resolution or the drawing data of the second resolution and held, and the held drawing data of the first resolution and drawing of the second resolution Discriminating information indicating which drawing data of the first resolution or the second resolution is to be used preferentially when performing the combining process on the drawing data of the first resolution. And the synthesizing means performs the synthesizing process based on the discrimination information.

  Furthermore, in the above-described invention, a preferable aspect thereof is that the first resolution is a resolution requested by a request source that requests the image forming apparatus to form an image, and the second resolution is greater than the first resolution. It is characterized by low resolution.

  Further, in the above invention, a preferred aspect is that the expansion means expands the drawing data of the first resolution when the type of the object is a character, and the second resolution when the type of the object is not a character. It develops into drawing data.

  In the above invention, a preferred aspect is characterized in that the synthesizing means performs the synthesizing process at the first resolution.

  Furthermore, in the above invention, a preferred aspect is that, when the expansion means expands and holds the drawing data of the first resolution, the discrimination information of the drawing data is converted into the first information during the combining process. The drawing data of the resolution is preferentially used, and when the drawing data of the second resolution is expanded and held, the determination information of the drawing data of the first resolution in the same area as the drawing data is It is characterized in that the drawing data of the second resolution is preferentially used in the synthesis process.

  Further objects and features of the present invention will become apparent from the embodiments of the invention described below.

  Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention. In the drawings, the same or similar elements are denoted by the same reference numerals or reference symbols.

  FIG. 1 is a configuration diagram according to an embodiment of an image forming apparatus to which the present invention is applied. A printer 2 shown in FIG. 1 is an image forming apparatus according to this embodiment, and executes printing on a print medium such as paper based on a print request from the host computer 1. When such a printer 2 expands data from an object unit to data for each pixel, it executes processing at a low resolution for a predetermined type of image, and speeds up the processing without degrading the image quality for high resolution data. It is what.

  A host computer 1 shown in FIG. 1 is a host device that makes a print request to the printer 2 and transmits print data to be printed to the printer 2 based on a user operation or the like. The host computer 1 can be configured by a so-called personal computer. Although not shown, the host computer 1 includes an application that is a print request source and a printer driver that generates the print data to be transmitted to the printer 2 based on a print request from the application. The print data that is generated and transmitted is expressed in a page description language such as PDL that expresses an image in object units, and resolution information to be printed by the printer 2 is also sent from the printer driver to the printer 2. For example, it is assumed here that printing is required at 1200 dpi.

  The printer 2 is a so-called 4-cycle laser printer that receives print data transmitted from the host computer 1 and executes printing in units of pages, and includes a controller 3 and an engine 4 as shown in FIG. ing. The controller 3 includes an I / F 31, a CPU 32, a ROM 33, an SDRAM 34, and a video I / F 35.

  The I / F 31 is a part that receives the print data transmitted from the host computer 1, and the ROM 33 is a part that stores various programs for controlling the printer 2.

  The SDRAM 34 is a Synchronous Dynamic Random Access Memory, which stores the received PDL format print data, intermediate codes obtained by dividing the print data into bands, rendering data expanded into data for each pixel, and data after color conversion processing. To do.

  FIG. 2 is a diagram for explaining each area for the drawing data and the data after color conversion processing stored in the SDRAM 34. 2A and 2B are areas for storing drawing data. In this printer 2, a character drawing area 341 for storing drawing data generated for a character image object, and an image The image drawing area 342 for storing drawing data generated for the image object is provided. This is one characteristic of the printer 2.

  As described above, the drawing data is data obtained by developing image data expressed in units of objects into data in units of pixels, and each pixel has a density value and attribute information. FIG. 2A illustrates an area for holding the drawing data for characters for one band obtained by dividing the area for one page of printing at a predetermined height. In the character drawing area 341, In this example, the high resolution required by the host computer 1 is maintained, and in this example, the drawing data of each pixel at 1200 dpi is held.

  For example, the hatched portion shown in FIG. 2A shows a case where the data of the character “−” is expanded and stored in the character drawing area 341, and each density value of RGB is set for each pixel. (For example, 8 bits × 3) and attribute information represented by X (for example, 8 bits) are stored. Therefore, for example, 32-bit data is stored for each pixel. The attribute information includes information indicating what kind of processing is to be performed in the color conversion processing and screen processing performed thereafter. Further, in the printer 2, as shown in the figure, the attribute information X stores what is a discriminator. This discriminator is a 1 bit for determining whether to use data stored in the character drawing area 341 or data stored in the image drawing area 342 when performing drawing data combining processing described later. Information. Having such a discriminator is also one of the features of the printer 2.

  As described above, the image drawing area 342 shown in FIG. 2B is an area for storing drawing data about the image. Unlike the character drawing area 341, the image drawing area 342 has a lower resolution than the requested resolution. The drawing data obtained as a result of the expansion process is stored. In this example, the data is developed at 600 dpi, and the data of each pixel at the resolution is stored. The data stored for each pixel is 32 bits of each color information and attribute information (RGBX) as in the case of the character drawing area 341, but the above-described discriminator is not included in the attribute information X. As described above, since the image drawing area 342 stores data having a lower resolution than the character drawing area 341, the area for storing drawing data for the same band is small. For example, in FIG. 2B, data for 4 pixels is stored, but this print area corresponds to data of an area for 16 pixels in the character drawing area 341.

  FIG. 2C illustrates an area for storing data after color conversion processing from RGB to CMYK (cyan, magenta, yellow, black) performed after development into drawing data. In the printer 2, during the color conversion process described later, since the data stored separately in the character drawing area 341 and the image drawing area 342 are combined into one, the area is combined. This is referred to as a region 343.

  This post-combination area 343 is prepared to contain the requested high resolution data, that is, data in this example at 1200 dpi. The stored drawing data illustrated in FIGS. 2A and 2B are combined and stored as shown in FIG. 2C, for example, as a result of the color conversion process.

  The CPU 32 is a part that controls various processes performed in the printer 2, and is particularly characterized by a development process for generating drawing data from the intermediate code. The specific contents will be described later. The processing executed by the CPU 32 is mainly performed according to a program stored in the ROM 33.

  Next, the video I / F 35 is a part that executes the color conversion process, the screen process, and the like, and the processed video data is delivered to the engine 4 from here. The video I / F 35 is specifically composed of an ASIC.

  Each part of the controller 3 described above is connected to be able to exchange data with each other as shown in FIG.

  Next, the engine 4 is a part that executes print processing based on data output from the video I / F 35 and forms an image on a print medium such as paper. The engine 4 includes a charging unit, an exposure unit, a developing device, a transfer unit, and the like (not shown) as in a normal laser printer.

  In the printer 2 according to this embodiment having the configuration described above, processing is performed in the following procedure when printing is performed. First, when print data by the above-described PDL is transmitted from the host computer 1, the I / F 31 receives the data and stores it in the SDRAM 34. Thereafter, the received data is divided into bands and converted into intermediate codes, and the intermediate codes are stored again in a predetermined area of the SDRAM 34. Next, expansion processing is executed on the stored intermediate code, and the above-described drawing data is generated. The generated drawing data is divided into two areas and stored as described above, and then the drawing data is subjected to color conversion processing and compression processing to be combined and stored again in the SDRAM 34. Thereafter, the generated data is taken out at a timing synchronized with the operation of the engine 4 and is output to the engine 4 after performing screen processing or the like. The engine 4 executes printing on a print medium based on the data.

  The printer 2 that executes the processing as described above has features in the above-described development processing and color conversion processing, and the specific contents thereof will be described below. FIG. 3 is a flowchart illustrating an example of a processing procedure during the development process and the color conversion process. Hereinafter, with reference to FIG. 3, the procedure of the expansion process from the intermediate code and the subsequent color conversion process for one band of data will be described.

  First, the CPU 32 reads data of one object from the intermediate code of the band to be processed (step S1). Then, when the object of the read data is a character (text) (Yes in step S2), the CPU 32 executes the expansion process with the requested high resolution (1200 dpi) (step S3), and reads the read data. Is not a character (No in step S2), the expansion process is executed at a low resolution (600 dpi) (step S5).

  Then, when the development process is performed at a high resolution and drawing data for each pixel is generated, the CPU 32 sets the value of the discriminator described above in the drawing data of each pixel to “1”, and sets the data to the character drawing area. The data is stored at a predetermined position 341 (step S4).

  On the other hand, when the development process is performed at a low resolution, the drawing data after the development process is stored at a predetermined position in the image drawing area 342 (step S6). Then, the CPU 32 sets the value of the discriminator included in the attribute information X to “0” for the pixels in the range of the character drawing area 341 corresponding to the range of the image drawing area 342 storing the data (step S7). .

  In this way, when the development processing and drawing data storage processing for one object are completed, the processing from step S1 to step S8 is repeated until the processing for all objects is completed for the target band. Do it.

  4 to 7 are diagrams for explaining specific examples of the above-described processing at the time of expansion. (A) and (b) in each of the drawings are respectively performed for one object. The drawing shows the state of the character drawing area 341 and the state of the image drawing area 342 when the drawing data is stored in the SDRAM 34. In addition, symbols such as “A” and “B” shown in each pixel in the drawing mean rendering data after development for the objects A and B of the same symbol, and each of the above-described RGBX It consists of data.

  In this specific example, it is assumed that processing is sequentially performed on four objects (A, B, C, and D). First, data of the first object A is read. Since the object A is an image, the process proceeds to the above-described step S5, and the expansion process is performed at 600 dpi. Thereafter, the generated drawing data “A” is stored in a state as shown in FIG. Then, the value of the discriminator is set to “0” for the drawing data of the hatched portion shown in FIG. 4A corresponding to the range in which “A” is stored, by the process of step S7 described above.

  Thereafter, the processing shifts to the second object B, and the data is read out. However, since the object B is a character, the processing shifts to step S3. Then, the expansion process is performed at 1200 dpi, and the drawing data “B” is stored in a state as shown in FIG. Note that the value of the discriminator in each stored data of “B” is set to “1”. At this time, the state of the image drawing area 342 is not changed.

  Next, the data of the object C is read, and since the object is an image, development processing is performed at 600 dpi, and drawing data “C” is stored as shown in FIG. 6B. As in the case of the object A, the value of the discriminator in the shaded area shown in FIG. 6A is set to “0”. Here, the drawing data “B0” in the hatched portion in FIG. 6A means that the value of the discriminator of the drawing data “B” based on the object B described above is set to “0”.

  Finally, since the fourth object D is processed and the object D is a character, the expansion process is performed at 1200 dpi, and the drawing data “D” is stored in a state as shown in FIG. Is done. Note that the value of the discriminator in each stored data of “D” is set to “1”. At this time, the state of the image drawing area 342 is not changed.

  As described above, the expansion and storage processing in the specific example is performed.

  Returning to FIG. 3, as described above, when the expansion and storage processing for the band to be processed is completed (Yes in step S8), the processing shifts to color conversion processing. Here, the drawing data stored separately in the two types is processed together, and the two types of drawing data are combined together with the color conversion processing.

  First, data for one pixel is read from the character drawing area 341 of the SDRAM 34 to the video I / F 35 (step S9). The order of the pixels to be read out is the direction from the upper left to the right of the band to be processed. Next, the video I / F 35 checks the value of the discriminator included in the read pixel data, and if the value is “1” (Yes in step S10), the drawing data of the read pixel is used. The color conversion process is executed, and the processed data is stored in the post-combination area 343 (step S11). Specifically, color conversion processing is performed based on the RGB data of the pixel stored in the character drawing area 341, and the generated CMYK data is stored at the same position as the pixel in the post-synthesis area 343.

  On the other hand, when the value of the discriminator is not “1”, that is, when it is “0” (No in step S10), the data of the pixel in the image drawing area 342 corresponding to the same position as the pixel from which the data has been read out. The data is read out and color conversion processing is executed based on the RGB values of the data. The processed CMYK data is stored in the post-combination area 343 (step S12). The storage position is a position corresponding to the position of the pixel from which data was read out in step S9.

  As described above, in the video I / F 35 of the printer 2, if the value of the discriminator included in the drawing data stored in the character drawing area 341 is “1”, the data in the character drawing area 341 is used to perform color conversion processing. If the discriminator value is “0”, color conversion processing is performed using data in the image drawing area 342. That is, based on the value of the discriminator, it is determined which of the drawing data divided into two locations is used during the expansion process in the process after the expansion process. In other words, the drawing data divided and stored in two places are synthesized based on the priority according to the value of the discriminator. Note that the video I / F 35 may store data in the post-combination area 343 after performing color conversion processing and then performing data compression processing to reduce the data capacity.

  As described above, the color conversion process and the synthesis process are performed on the data for one pixel, but the above-described steps S9 to S13 are performed until the process is executed for all the pixels in the processing target band. This process is repeated. If the processing is completed for all the pixels (Yes in step S13), the color conversion and synthesis processing for the band to be processed is completed.

  FIG. 8 is a diagram for explaining color conversion and synthesis processing for the specific examples shown in FIGS. FIGS. 8A and 8B show drawing data stored in two places, a character drawing area 341 and an image drawing area 342, after the expansion process is completed. That is, it is the same as the state shown in FIG. Further, FIG. 8C shows a state in which data obtained as a result of the color conversion and synthesis processing on the drawing data is stored in the post-synthesis area 343.

  The color conversion and composition processing is sequentially performed as described above in the order of the arrows shown in FIG. For example, for the upper left pixel in FIG. 8A, as described with reference to FIG. 4, the discriminator value is “0”, so the same position stored in the image drawing area 342. The drawing data “A” is used for the color conversion process, and the resulting data “A” is stored in the pixel at the same position in the combined region 343. Note that the processed data “A”, “B”, and the like shown in FIG. 8C are data obtained as a result of color conversion processing based on the drawing data “A”, “B”, and the like, respectively. It means that.

  Further, for example, for the pixel having the drawing data “B” in FIG. 8A, as described above, the discriminator value is “1”, and therefore the drawing data “B” stored therein is stored. Is used for color conversion processing, and the resulting data “B” is stored in the pixel at the same position in the post-combination area 343.

  Further, in the pixel having the drawing data “B0” in FIG. 8A, the discriminator value is “0” as described above, so that the same position stored in the image drawing area 342 is stored. The drawing data “C” is used for the color conversion process, and the resulting data “C” is stored in the pixel at the same position in the combined region 343.

  In this way, when the processing is performed for all the pixels in one band, the state shown in FIG. 8C is obtained, and the color conversion processing is completed and the drawing that has been stored separately in two places is drawn. Data synthesis is also completed. The data stored here is used for subsequent screen processing and the like.

  As described above with reference to FIG. 3 and the like, the expansion processing and color conversion processing for one band in the printer 2 are performed.

  As described above, in the printer 2 according to the present embodiment, the character object is processed at the requested high resolution when the data for each object is developed into the data for each pixel, and the image data is processed. The object is processed at a resolution lower than the requested resolution to generate two types of drawing data. In the drawing data attribute information, a discriminator indicating which of the two types of drawing data is used in the subsequent processing is incorporated. Then, at the time of the color conversion process, a combination process of two types of drawing data is also performed based on this discriminator.

  Therefore, in the printer 2, in the development process in which the CPU 32 repeatedly accesses the memory (SDRAM 34), the number of accesses can be reduced as compared with the case where all objects are processed at a high resolution. It can be performed at high speed. In addition, with respect to an image that is developed at a low resolution, deterioration in image quality due to this is not conspicuous, and the quality of the entire image output from the printer 2 is not greatly deteriorated. Further, the process of combining the drawing data divided into the high resolution and the low resolution can be easily performed by a discriminator included in the drawing data, and the composition is performed by the video I / F 35 configured by the ASIC. Since it is performed together with hardware processing during the conversion processing, processing time is not increased. Further, the discriminator is incorporated in the attribute information area of the drawing data and does not increase the amount of drawing data as compared with the prior art.

  In the above-described embodiment, the process of combining the two pieces of drawing data is performed at the time of the color conversion process. However, the color conversion process is performed on each of these two types of drawing data, and the process is performed. The later data may be stored separately in the SDRAM 34. In this case, processing that is synchronized with the engine 4 described later, that is, processing that sequentially reads out the data after color conversion in accordance with the operation of the engine 4 and outputs screen processing and the like to the engine 4 after execution. In this case, data divided into two types of resolutions are synthesized. Even in such a case, the information of the discriminator is used in the same manner, and the same effect as that described above can be obtained.

  In the above embodiment, the host computer 1 requests to print at a high resolution (1200 dpi). When the host computer 1 issues a print request, the resolution is designated for each object. You may do it. For example, a print request is made by designating that characters are printed at a high resolution (1200 dpi) and images are printed at a low resolution (600 dpi). On the printer 2 side, processing is performed in the same manner as in the above embodiment. The resolution for each object is specified by the printer driver described above.

  In the above embodiment, the printer 2 performs processing by dividing into two types of resolutions during the development processing, but it is also possible to perform processing by dividing into three or more types of resolutions. For example, when dividing into three types of resolutions, the objects to be expanded are classified into three types according to a predetermined index such as the type of object, and the processed drawing data is one of three drawing regions with different resolutions. Stored in For subsequent synthesis, a discriminator composed of 2-bit data is incorporated into any one type of drawing data, and one of the three types of drawing data is used with priority according to the discriminator value. Try to determine what to do.

  In the above embodiment, the resolution is 1200 dpi when the object is a character and 600 dpi when the object is an image. However, this is only an example, and other types of objects are appropriately used as indices. Or other resolutions may be used.

  The protection scope of the present invention is not limited to the above-described embodiment, but covers the invention described in the claims and equivalents thereof.

1 is a configuration diagram according to an embodiment of an image forming apparatus to which the present invention is applied. FIG. 4 is a diagram for explaining each area of the SDRAM 34; It is the flowchart which illustrated the process sequence at the time of an expansion | deployment process and a color conversion process. It is a figure for demonstrating the specific example at the time of an expansion | deployment process. It is a figure for demonstrating the specific example at the time of an expansion | deployment process. It is a figure for demonstrating the specific example at the time of an expansion | deployment process. It is a figure for demonstrating the specific example at the time of an expansion | deployment process. It is a figure for demonstrating the specific example at the time of color conversion and a synthetic | combination process.

Explanation of symbols

  1 host computer, 2 printer, 3 controller, 4 engine, 31 I / F, 32 CPU (developing means), 33 ROM, 34 SDRAM (developing means), 35 video I / F (compositing means), 341 character drawing area, 342 Image drawing area, 343 Post-combination area

Claims (5)

An image forming apparatus that develops image data in object units into drawing data in pixel units and forms an image based on the drawing data.
Expanding means for expanding and holding the image data in the drawing data of the first resolution or the drawing data of the second resolution according to the type of the object;
A synthesis means for synthesizing the held first resolution drawing data and second resolution drawing data;
The first resolution drawing data includes discrimination information indicating which drawing data of the first resolution or the second resolution is preferentially used when performing the synthesis processing, and the synthesis means An image forming apparatus that performs the composition processing based on information. In claim 1,
The first resolution is a resolution requested from a request source that makes an image formation request to the image forming apparatus,
The image forming apparatus, wherein the second resolution is lower than the first resolution. In claim 1 or claim 2,
The expansion means expands the drawing data of the first resolution when the type of the object is a character, and expands the drawing data of the second resolution when the type of the object is not a character. Image forming apparatus. In any one of Claim 1 thru | or 3,
The image forming apparatus, wherein the combining unit performs the combining process at the first resolution. In any one of Claims 1 thru | or 4,
When the expansion means expands and holds the drawing data of the first resolution, the drawing information of the first resolution is preferentially used for the determination information of the drawing data during the combining process. When the drawing data of the second resolution is expanded and held, the determination information of the drawing data of the first resolution in the same area as the drawing data is used to draw the drawing of the second resolution. An image forming apparatus characterized in that data is used preferentially.

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