JP2006076017A - Image forming apparatus - Google Patents

Abstract

An object of the present invention is to provide a method that does not add attribute information to white pixels or consecutive pixels of the same attribute, so that memory can be used efficiently and optimal image processing can be executed for each object even in the case of complex data. And
Attribute information adding means for adding a plurality of attribute signals representing data attributes for each pixel of bitmap data generated by a raster image generating means, and a logical sum for generating a logical sum signal from the bitmap data Signal synthesizing means and means for storing the logical sum signal in a storage device, and whether to add an attribute signal to each pixel constituting the raster image based on the logical sum signal generated by the logical sum signal synthesizing means. Means for selecting, means for selecting whether or not to store the attribute signal of each pixel in the storage device, and means for storing the attribute signal of each pixel determined to be stored in the storage device by the selection means in the storage device And have.
[Selection] Figure 1

Description

  The present invention relates to an image forming apparatus such as a printing apparatus controlled by a printer controller connected to a host computer or another device, and more particularly to each object of raster data generated according to a drawing command for each object. The present invention relates to an image forming apparatus that adds attribute information for performing optimum image processing and enables improvement in print image quality.

In a conventional attribute information addition method in an image forming apparatus, attribute information for performing optimum image processing for each object is added to all pixels of raster data generated according to a drawing command. If drawing data is complicated, the amount of memory consumption will increase. Therefore, if the memory usage is limited to a certain amount or if a common memory area is used for other processing, other processing will be performed. In order to secure a usable memory area, a method is adopted in which attribute information is deleted and the same attribute value is added to the entire surface (Patent Document 1).
JP 2003-259140 A

  In the attribute information addition method in the image forming apparatus of the conventional example described above, the memory consumption increases when the drawing processing is complicated data. Therefore, the memory usage is limited to a certain amount or common with other processing. If you are using one memory area, the image information is deleted and the same attribute value is added to the entire surface to secure a memory area that can be used by other processes. There was a problem that sometimes could not be executed.

  The present invention has been made in view of the above problems, and by providing a method that does not add attribute information to white pixels or consecutive pixels of the same attribute in an image, the memory can be used efficiently and complicated data can be used. Even in this case, optimal image processing for each object can be executed.

  The image forming apparatus of the present invention that achieves the above object has the following configuration.

  According to a first aspect of the present invention, there is provided an image forming apparatus for generating a drawing object by analyzing print data based on a plurality of page description languages, a means for generating a raster image based on a drawing command, and the raster image generation Attribute information adding means for adding a plurality of attribute signals representing data attributes for each pixel of bitmap data generated by the means, and a logical sum signal for generating a logical sum signal from the bitmap data obtained by the raster image generating means Synthesizing means, and means for storing the logical sum signal obtained by the logical sum signal synthesizing means in a storage device, and attributes each pixel constituting the raster image based on the logical sum signal generated by the logical sum signal synthesizing means. A means for selecting whether or not to add a signal, and a logical sum signal generated by the logical sum signal synthesis means. And a means for selecting whether or not to store the attribute signal of each pixel in the storage device, and a means for storing the attribute signal of each pixel determined to be stored in the storage device by the selection means in the storage device. It is.

  According to a second aspect of the present invention, the total amount of the attribute signal which is determined by the storage means based on the logical sum signal stored in the storage device and the logical sum signal is described in the first aspect. A storage amount determination unit that determines whether or not the total amount of attribute signals added to all the pixels by the attribute information addition unit exceeds the total amount of the logical sum signal and the attribute signal of each pixel by the storage amount determination unit. When it is determined that the total amount of attribute signals added by the attribute information adding means according to the first invention is exceeded, the logical sum signal stored by the storage means and the attribute signal of each pixel are stored in the storage means. A restoring means for restoring the attribute signal that has not been performed, a storage means for storing the attribute signal restored by the restoring means in a storage device, and a theory for deleting the logical sum signal from the storage means. Is that in which a sum signal deleting means.

  According to a third aspect of the present invention, there is provided an image forming apparatus for generating a drawing object by analyzing print data based on a plurality of page description languages, a means for generating a raster image based on a drawing command, and the raster image generation Attribute information adding means for adding a plurality of attribute signals representing data attributes to each pixel of bitmap data generated by the means, and changes for extracting change points of the bitmap data and attribute information obtained by the raster image generating means Means for storing a change point signal obtained by the point signal extraction means in a storage device, and adding the same attribute signal to a plurality of pixels constituting the raster image based on the change point signal generated by the change point signal extraction means Based on a change point signal generated by the change point signal extraction means and the change point signal extraction means. Means for selecting whether or not the attribute signal determined to be valid for the pixel is stored in the storage device; and means for storing in the storage device the attribute signal determined to be stored in the storage device by the selection means. It is to have established.

  According to a fourth aspect of the present invention, there is provided the change point signal stored in the storage device by the storage means and the total amount of attribute signals determined whether or not to hold based on the change point signal. A storage amount determination unit for determining whether or not the total amount of attribute signals added to all pixels by the attribute information addition unit is larger than the total amount of the change point signal and the attribute signal of each pixel by the storage amount determination unit. When it is determined that the total amount of attribute signals added by the attribute information adding means according to the third invention is exceeded, the change point signal stored by the storage means and the attribute signal of each pixel are stored in the storage means. A restoring means for restoring the attribute signal that has not been restored, a storage means for storing the attribute signal restored by the restoring means in a storage device, and a variable for deleting the change point signal from the storage means. Is that provided the point signal deleting means.

  According to a fifth aspect of the present invention, there is provided means for measuring a white pixel occurrence rate of bitmap data generated by the raster image generation means, means for measuring a pixel occurrence rate to which no change point signal is added, Based on the logical sum signal and the logical sum signal based on the occurrence rate obtained by the white pixel occurrence rate measuring means and the change point signal occurrence rate measuring means and the number of bits of attribute information added to each pixel as an attribute signal. Whether or not the total amount of attribute signals that have been determined whether or not the total amount of attribute signals that have been determined based on the change point signal and the change point signal is greater than the total amount of attribute signals that are added to all pixels Means for selecting the means for generating the least amount of memory according to the determined result, the attribute signal generation method selecting means for selecting the means with the smallest memory usage, and the attribute selected by the selecting means. It is providing the means for storing generated in the storage device attribute signal by the signal generating method.

[Action]
In such a configuration, it is possible to add a plurality of attribute signals, generate a logical sum signal of each attribute signal, and select whether to store the attribute signal in the storage device according to the presence or absence of the logical sum signal. As a result, the memory usage of the attribute signal can be suppressed as compared with the conventional method.

  Furthermore, it is possible to generate a change point signal for each attribute signal and select whether to store the attribute signal in a storage device according to the presence or absence of the change point signal, thereby reducing the memory usage of the attribute signal in the past. It becomes possible to suppress rather than the method.

  According to the present invention, it is possible to add a plurality of attribute signals, generate a logical sum signal of each attribute signal, and select whether to store the attribute signal in a storage device according to the presence or absence of the logical sum signal. By doing so, an effect of suppressing the memory usage of the attribute signal as compared with the conventional method is obtained.

  Furthermore, according to the present invention, it is possible to add a plurality of attribute signals, generate a change point signal of each attribute signal, and select whether to store the attribute signal in the storage device according to the presence or absence of the change point signal By doing so, an effect of suppressing the memory usage of the attribute signal as compared with the conventional method can be obtained.

  First, a configuration example of a laser beam printer will be described as an example of an output device to which the embodiment of the present invention can be applied. The present embodiment is applicable not only to laser beam printers but also to other types of output devices such as inkjet printers and MFPs (Multi Function Printers).

  FIG. 1 is a block diagram showing the configuration of a laser beam printer as a first embodiment of the printing apparatus of the present invention, FIG. 2 is a diagram schematically showing the mechanism of the laser beam printer of FIG. 1, and FIG. It is a block diagram which shows the structure of the printer controller mounted in the laser beam printer of FIG.

  In FIG. 1, a data processing apparatus 101 is a computer, for example, and functions as a source of image information or a printer control apparatus. In this embodiment, a laser beam printer (printer) is used as the image recording apparatus 102.

  The printer controller 103 generates bitmap data for each page based on image information (for example, ESC code, page description language, etc.) supplied from the data processing apparatus 101, and sends it to the printer engine 105.

  The printer engine 105 forms a latent image on the photosensitive drum based on the bitmap data supplied from the printer controller 103, and transfers and fixes the latent image on the recording medium (electrophotographic method). Record.

  The panel unit 104 is used as a user interface. The user can instruct a desired operation by operating the panel unit 104. The panel unit 104 displays processing contents of the printer 102 and warning contents to the user.

  Next, the configuration of the laser beam printer taken up as an example of the embodiment in this embodiment will be described with reference to FIG.

  FIG. 2 is a cross-sectional view illustrating the configuration of the tandem color printer 102.

  In the figure, 201 is a printer housing. Reference numeral 202 denotes an operation panel on which a switch for giving various instructions by the user, an LED display, an LCD display, and the like for displaying messages, printer settings, and the like are arranged. It is one mode. Reference numeral 203 denotes a board housing unit that houses boards constituting the electronic circuit portions of the printer controller 103 and the printer engine 105.

  A paper cassette 220 holds the paper (recording medium) S and has a mechanism for electrically detecting the paper size by a partition plate (not shown). Reference numeral 221 denotes a cassette clutch which takes out the uppermost sheet S of the paper S placed on the paper cassette 220 and feeds the taken paper S by a driving force transmitted from a driving means (not shown). It has a cam that conveys up to The cam rotates intermittently each time a sheet is fed, and feeds one sheet S corresponding to one rotation. Reference numeral 223 denotes a paper detection sensor that detects the amount of paper S held in each paper cassette 220.

  The paper feed roller 222 is a roller that conveys the leading edge of the paper S to the registration shutter 224. Reference numeral 224 denotes a registration shutter that can stop paper feeding by pressing the paper S.

  230 is a manual feed tray, and 231 is a manual paper feed clutch. The manual paper feed clutch 231 is used for conveying the leading edge of the paper S to the manual paper feeding roller 232, and the manual paper feeding roller 232 is used for conveying the leading edge of the paper S to the registration shutter 224. The sheet S to be used for image recording is fed by selecting one of the sheet cassette 220 and the manual feed tray 230.

  The printer engine 105 communicates with the printer controller 103 according to a predetermined communication protocol, selects one of the paper feeding means from the paper cassette 220 manual feed tray 230 according to an instruction from the printer controller unit 103, and starts printing. In response to the instruction, the sheet S is conveyed from the corresponding sheet feeding means to the registration shutter 224. The printer engine 105 includes a sheet feeding unit, a mechanism relating to an electrophotographic process such as formation, transfer, and fixing of a latent image, a sheet discharge unit, and a control unit thereof.

  204a, 204b, 204c, and 204d are image recording units having photosensitive drums 205a, 205b, 205c, and 205d, a toner holding unit, and the like, and form a toner image on the sheet S by an electrophotographic process. On the other hand, 206a, 206b, 206c, and 206d are laser scanner units that supply image information by a laser beam to the image recording unit.

  In the image recording units 204a, 204b, 204c, and 204d, a sheet conveying belt 250 that conveys the sheet S is flattened in a sheet conveying direction (from the bottom to the top in the figure) by a plurality of rotating rollers 251 to 254. In the most upstream area, the sheet is electrostatically attracted to the sheet conveying belt 250 by the attracting roller 225 to which a bias is applied. Further, four photosensitive drums 205a, 205b, 205c, and 205d are arranged in a straight line so as to face the belt conveyance surface, and constitute an image forming unit. In each of the image recording units 204a, 204b, 204c, and 204d, a charger and a developing device are disposed so as to sequentially surround the vicinity of the periphery of the photosensitive drum.

  In the laser scanner units 206a, 206b, 206c, and 206d, reference numerals 207a, 207b, 207c, and 207d are laser units that drive a built-in semiconductor laser in accordance with an image signal (/ VIDEO signal) sent from the printer controller 103. And fire a laser beam. Laser beams emitted from the laser units 207a, 207b, 207c, and 207d are scanned by polygon mirrors (rotating polygon mirrors) 208a, 208b, 208c, and 208d to form latent images on the photosensitive drums 205a, 205b, 205c, and 205d. To do.

  A fixing unit 260 heat-fixes the toner image formed on the sheet S by the image recording units 204a, 204b, 204c, and 204d on the recording sheet S. Reference numeral 261 denotes a conveyance roller that discharges and conveys the paper S. A paper discharge sensor 262 detects a paper discharge state of the paper S. Reference numeral 263 denotes a paper discharge roller / double-sided printing transport path switching roller that transports the paper S in the paper discharge direction. If the transport instruction of the paper S is a paper discharge, the paper S is discharged to the paper discharge tray 264 as it is. In the case of double-sided conveyance, immediately after the trailing edge of the paper S passes the paper discharge sensor 262, the rotation direction is changed to the reverse direction, and the paper S is conveyed to the double-sided printing conveyance path 270 by switching back. Reference numeral 265 denotes a discharge stack amount detection sensor that detects the stack amount of the sheets S stacked on the discharge tray 264.

  Reference numeral 270 denotes a duplex printing conveyance path. The sheet S conveyed for duplex printing by the paper discharge roller / double-sided printing conveyance path switching roller 263 is conveyed again to the registration shutter 224 by the duplex conveyance rollers 271 to 274. Waiting for a conveyance instruction to the image recording units 204a, 204b, 204c, and 204d.

  The printer 102 can be further equipped with optional units such as an optional cassette and an envelope feeder.

  Next, the configuration of the printer controller 103 will be described with reference to FIG.

  The printer controller 103 includes an input buffer (not shown) for inputting print data sent from the data processing apparatus 101 and settings for instructing the operation of the apparatus, and an output including a signal sent to the data processing apparatus 101 and device information data. The host I / F unit 302 is provided with an output buffer (not shown) that temporarily stores data. The host I / F unit 302 includes signals exchanged with the data processing apparatus 101, The communication packet input / output unit is configured, and communication control with the data processing apparatus 101 is performed.

  The print data input via the host I / F unit 302 is given to the image data generation unit 303. An image data generation unit 303 analyzes input print data (for example, PDL analysis processing) based on a predetermined analysis unit, generates a drawing object as an intermediate language from the analysis result, and can be further processed by the printer engine 105. Bitmap data generation is performed. Specifically, print data is analyzed and object information is created by the analysis, and rasterization processing is performed in parallel with the creation of the object information. In this rasterizing process, the display color RGB (additive color mixture) included in the print data is converted to YMCK (subtractive color mixture) that can be processed by the printer engine, the bit pattern and outline stored in advance from the character code included in the print data Performs conversion to font data such as fonts, creates bitmap data in page units or band units, applies pseudo-gradation processing using a dither pattern to the bitmap data, and allows printing processing in the printer engine Generate bitmap data.

  The created bitmap data is stored in the image memory 305. Reading of the bitmap data stored in the image memory 305 is controlled by the DMA control unit 308, and the control for reading the bitmap data from the image memory 305 by the DMA control unit 308 is performed based on an instruction from the CPU 309.

  The bitmap data read from the image memory 305 is transferred to the printer engine 105 as a video signal via the engine I / F unit 306. The engine I / F unit 306 includes an output buffer (not shown) that temporarily holds a video signal to be transferred to the printer engine 105 and an input buffer (not shown) that temporarily holds a signal sent from the printer engine 105. The engine I / F unit 306 constitutes an input / output unit for signals exchanged with the printer engine 105 and controls communication with the printer engine 105.

  Instructions relating to mode setting and the like issued by operation input from the panel unit 104 (shown in FIG. 1) are input via the panel I / F unit 301, and the panel I / F unit 301 is connected between the panel unit 104 and the CPU 309. (The instruction to the printing apparatus such as the mode setting issued by the operation input can also be instructed via the host I / F unit 302 that performs bidirectional communication with the external connection device).

  The CPU 309 controls each block described above according to the mode instructed from the panel unit 104 or the data processing apparatus 101, and this control is executed based on a control program stored in the ROM 304. The control program stored in the ROM 304 includes an OS (operating system) for performing time-sharing control in units of load modules called tasks according to a system clock, and a plurality of load modules that are executed and controlled in units of functions by the OS. It consists of. A control program including the load module is stored in an EEPROM (nonvolatile memory) 310 as necessary.

  A RAM 307 is used as a work area for arithmetic processing by the CPU 309. Each block including the above-described CPU 309 is connected to the system bus 320. The system bus 320 includes an address bus and a system bus.

  Next, the processing path of input data in the printer controller of FIG. 3 is shown for each functional block with reference to FIG.

  The print data input from the external connection device through the host interface unit (302) is command-analyzed by the PDL analysis unit (303a), and then generated as a drawing object (intermediate language) by the drawing object generation unit (303b). It is temporarily recorded in the upper working memory (307).

  The drawing memory is read from the working memory on the RAM as needed and rasterized (303c). The image data finally recorded on the recording medium is developed into a bitmap image and stored in the image memory (305). 306) and recording on a recording medium is performed.

  FIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, and FIG. 10 are flowcharts showing programs stored in the program ROM indicated by 304 in FIG.

  First, as a conventional example, attribute information adding means in a conventional image forming apparatus will be described with reference to FIG.

(Conventional example)
The print data input through the host interface and analyzed by the PDL analysis unit is developed in a DL (display list) (501), and the type of the object whose pixel fill is determined while performing the rendering process for generating the raster image is “ Attribute information indicating any of “character”, “figure”, and “image” is generated / added and stored in the storage device (502). The processing of 502 is repeatedly executed up to the final pixel constituting the raster image (503).

  If it is determined in step 503 that the last pixel has been processed, image processing for executing color processing or dither matrix processing is performed on the raster image (504). At this time, in image processing, a raster image and attribute table generated and stored in 502, and further, a bitmap that performs optimal image processing on the input print data with reference to a LUT or dither matrix stored in advance. An image is generated.

  Next, the bitmap image generated in 504 is stored in the image memory area (505), and the process is terminated.

  In the attribute information addition method in the conventional image forming apparatus, attribute information is added to each pixel of raster data generated according to the drawing command as attribute information addition means for improving the print image quality. There is a problem that the amount of memory required increases depending on the size.

  What improved this point is the program shown in the flowcharts of FIGS. 6, 7, 8, 9, and 10, which is a method of adding a plurality of attribute signals and reducing the storage capacity of each attribute signal. .

  Embodiments will be described below with reference to FIGS. 6, 7, 8, 9, and 10. FIG.

  Note that the processing inside the printing apparatus in this case is given as an example, and it is not always necessary to perform these operations.

  The print data input via the host interface and analyzed by the PDL analysis unit is expanded into a DL (display list) (601), and the type of the object whose pixel fill is determined while performing the rendering process for generating the raster image is “ Attribute information indicating whether it is any one of “character”, “figure”, and “image”, and OR signal data indicating whether attribute information is generated for each pixel are generated, and a logical sum signal and the logical sum are generated. Only attribute information generated for pixels for which the signal is valid is stored in the storage device (602). The process 602 is repeatedly executed up to the last pixel constituting the raster image (603).

  If it is determined in step 603 that the last pixel has been processed, image processing for performing color processing or dither matrix processing is performed on the raster image (604). In the image processing, the raster image generated and stored in 602, the logical sum signal, the attribute table, and the print data input by referring to the LUT and dither matrix stored in advance are processed. A bitmap image is generated.

  Next, the bitmap image generated in 504 is stored in the image memory area (505), and the process is terminated.

  As a specific example of this embodiment, FIG. 11 shows an example in which a method for reducing the amount of data to be generated and held as attribute information is used.

  As described above, it is possible to generate a logical sum signal of each attribute signal and select whether or not to store the attribute signal in a storage device according to the presence or absence of the logical sum signal. Is more effective than the conventional method.

  In the first embodiment, a method of suppressing the memory usage of an attribute signal by generating a logical sum signal of each attribute signal and selecting whether to store the attribute signal in a storage device according to the presence or absence of the logical sum signal In this embodiment, either the method for selecting whether or not to store the attribute signal in the storage device according to the presence or absence of the logical sum signal, or the conventional method for adding attribute information to all the pixels is used. A method that makes it possible to more effectively suppress the memory usage by determining whether the memory usage can be suppressed will be described.

  FIG. 7 is a flowchart showing an image processing method in this embodiment.

  Print data input via the host interface and analyzed by the PDL analysis unit is developed in a DL (display list) (701), pre-rendering processing is executed, and whether or not the pixel is filled is determined and logically ORed. A signal is generated and stored in a storage device (702).

  Next, the memory usage when the logical sum signal is used is calculated from the logical sum signal generated in 702 and the number of bits of the attribute information added to the pixel (703).

For example, when the number of logical sum signals is L, the total number of pixels of an image is M, and the number of bits of attribute information is k, the required memory amount is (L × k + M) bits.
On the other hand, the amount of memory required for the conventional processing method is M × k bit.
It is expressed.

  Next, the amount of memory used when the logical sum signal calculated in 703 is used is compared with the amount of memory used when attribute information is added to all pixels (704), and the memory when the logical sum signal is used is compared. When the usage amount decreases, attribute information indicating whether the type of the object for which the pixel fill is determined while performing the rendering process is “character”, “figure”, or “image” is generated, and the logical sum signal and the above-mentioned Only attribute information generated for pixels for which the logical sum signal is valid is stored in the storage device (705). The processing of 705 is repeatedly executed up to the last pixel constituting the raster image (706).

  On the other hand, if it is determined in 704 that the memory usage is reduced when attribute information is added to all the pixels, the attribute information is added to all the pixels while performing rendering processing and saved in the storage device (709). ). The processing of 709 is repeatedly executed up to the last pixel constituting the raster image (710), as in 705.

  Further, if it is determined in 706 or 710 that the last pixel has been processed, image processing for executing color processing or dither matrix processing is executed on the raster image (707). In the above image processing, the raster image and logical sum signal and attribute table generated and stored in 702, 705, and 709, and the print data input by referring to and using the pre-stored LUT and dither matrix are used. A bitmap image is generated by performing optimum image processing.

  Next, the bitmap image generated in 707 is stored in the image memory area (708), and the process ends.

  As described above, according to this embodiment, either the method of selecting whether or not to store the attribute signal in the storage device according to the presence or absence of the logical sum signal or the conventional method of adding the attribute information to all the pixels is the memory. It is possible to more effectively suppress the memory usage by determining whether the usage can be suppressed.

  In the first and second embodiments, a method of suppressing the memory usage by generating a logical sum signal that holds whether or not a pixel is filled and retaining attribute information in the attribute table only for the pixel for which the logical sum signal is ON. As described above, in the present embodiment, a method for generating and using a change point signal of a filled area will be described.

  FIG. 8 is a flowchart showing an image processing method in this embodiment.

  The print data input via the host interface and analyzed by the PDL analysis unit is expanded to a DL (display list) (801), and the type of the object whose pixel fill is determined while performing the rendering process for generating the raster image is “ A change point signal for generating an ON bit is generated when the attribute information indicating whether the character, the figure, or the image is different from the attribute information of the (N−1) th pixel, and the change point signal and the change point are generated. Only the attribute information generated for the pixels for which the signal is valid is stored in the storage device (802). The process 802 is repeatedly executed up to the last pixel constituting the raster image (803).

  If it is determined in step 803 that the last pixel has been processed, image processing for executing color processing or dither matrix processing is performed on the raster image (804). In image processing, optimum image processing is performed on the input print data by referring to the raster image generated and stored in 802, the change point signal, the attribute table, and the LUT and dither matrix stored in advance. A bitmap image is generated.

  Next, the bitmap image generated in 804 is stored in the image memory area (805), and the process ends.

  As a specific example in the present embodiment, an example in which a method for reducing the amount of data to be generated and held as attribute information is shown in FIG.

  As described above, it is possible to generate a change point signal that turns on a pixel in which each attribute signal changes, and to select whether or not to store the attribute signal in a storage device according to the presence or absence of the change point signal. Thus, an effect of suppressing the memory usage of the attribute signal as compared with the conventional method can be obtained.

  In the third embodiment, a method of suppressing the memory usage of attribute information by generating a change point signal of each attribute signal and selecting whether or not to store the attribute signal in a storage device according to the presence or absence of the change point signal In this embodiment, either the method for selecting whether or not to store the attribute signal in the storage device according to the presence or absence of the change point signal or the conventional method for adding the attribute information to all the pixels is used. A method that makes it possible to more effectively suppress the memory usage by determining whether the memory usage can be suppressed will be described.

  FIG. 9 is a flowchart showing an image processing method in this embodiment.

  Print data input via the host interface and analyzed by the PDL analysis unit is expanded into a DL (display list) (901), and pre-rendering processing is executed to fill the Nth pixel and the N + 1th pixel. If they are different, a change point signal is generated as a change point of the attribute and stored in the storage device (902).

  Next, the memory usage when the change point signal is used is calculated from the change point signal generated in 902 and the number of bits of attribute information added to the pixel (903).

For example, when the number of change point signals is H, the total number of pixels of the image is M, and the number of bits of attribute information is k, the required memory amount is (H × k + M) bits.
On the other hand, the amount of memory required for the conventional processing method is M × k bit.
It is expressed.

  Next, the amount of memory used when the change point signal calculated in 903 is used is compared with the amount of memory used when attribute information is added to all pixels (904), and the memory when the change point signal is used is compared. When the usage amount decreases, attribute information indicating whether the type of the object for which the pixel painting is determined while performing the rendering process is “character”, “figure”, or “image” is generated, Only the attribute information generated for the pixels for which the change point signal is valid is stored in the storage device (905). The process 905 is repeatedly executed up to the last pixel constituting the raster image (906).

  On the other hand, if it is determined in 904 that the memory usage is reduced when the attribute information is added to all the pixels, the attribute information is added to all the pixels while performing the rendering process and stored in the storage device (909). ). The processing of 909 is repeatedly executed up to the last pixel constituting the raster image as in 905 (910).

  Further, if it is determined in 906 or 910 that the final pixel has been processed, image processing for executing color processing or dither matrix processing is executed on the raster image (907). In the above image processing, the raster image generated at 902, 905, and 909, the change point signal, the attribute table, and the print data input by referring to and using the LUT or dither matrix stored in advance are used. A bitmap image is generated by performing optimum image processing.

  Next, the bitmap image generated in 907 is stored in the image memory area (908), and the process ends.

  As described above, according to this embodiment, either the method of selecting whether or not to store the attribute signal in the storage device according to the presence or absence of the change point signal or the conventional method of adding the attribute information to all the pixels is the memory. It is possible to more effectively suppress the memory usage by determining whether the usage can be suppressed.

  In this embodiment, in order to further improve the memory use efficiency, when an OR signal is used according to input data and when a change point signal is used, an attribute signal is added to all the conventional pixels. In this case, the memory usage amount is calculated by pre-rendering and an optimum attribute table creation method is selected.

  Although details are omitted because they are developed versions of the second and fourth embodiments, the image processing method in this embodiment is shown in the flowchart of FIG.

1 is a block diagram showing a configuration of a laser beam printer as a first embodiment of a printing apparatus according to the present invention. 1 schematically shows the mechanism of the laser beam printer of FIG. 1 is a block diagram showing a configuration of a printer controller mounted on the laser beam printer of FIG. The figure which shows the input data processing in the printer controller of FIG. 3 according to a functional block A flowchart showing image processing in a conventional example 7 is a flowchart showing image processing in Embodiment 1 of the present invention. Flowchart showing image processing in Embodiment 2 of the present invention Flowchart showing image processing in Embodiment 3 of the present invention Flowchart showing image processing in Embodiment 4 of the present invention Flowchart showing image processing in Embodiment 5 of the present invention The figure which showed the relationship between the logical sum signal and attribute information table which are used in Examples 1-2 of this invention The figure which showed the relationship between the logical sum signal used in Example 3-4 of this invention, and an attribute information table

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Data processing apparatus 102 Image recording apparatus 103 Printer controller 104 Panel part 105 Printer engine 201 Printer housing 202 Operation panel 203 Board storage part 204a, 204b, 204c, 204d Image recording part 205a, 205b, 205c, 205d Photosensitive drum 206a, 206b , 206c, 206d Laser scanner units 207a, 207b, 207c, 207d Laser units 208a, 208b, 208c, 208d Polygon mirrors (rotating polygon mirrors)
220 Paper cassette 221 Cassette clutch 222 Paper feed roller 223 Paper detection sensor 224 Registration shutter 225 Adsorption roller 230 Manual feed tray 231 Manual paper feed clutch 232 Manual paper feed roller 250 Paper transport belt 251 to 254 Rotating roller 260 Fixing device 261 Transport roller 262 Ejection Paper sensor 263 Paper discharge roller / double-sided printing conveyance path switching roller 264 Paper discharge tray 265 Paper discharge stack amount detection sensor 270 Double-sided printing conveyance path 271 to 274 Double-sided conveyance roller 301 Panel I / F unit 302 Host I / F unit 303 Image data generator 304 ROM
305 Image memory 306 Engine I / F unit 307 RAM
308 DMA control unit 309 CPU
310 EEPROM
311 hard disk 320 system bus

Claims (5)

  An image forming apparatus for generating a drawing object by analyzing print data based on a plurality of page description languages, a means for generating a raster image based on a drawing command, and a bitmap data generated by the raster image generating means Attribute information adding means for adding a plurality of attribute signals representing data attributes for each pixel, OR signal synthesizing means for generating an OR signal from bitmap data obtained by the raster image generating means, and the OR signal synthesis Means for storing a logical sum signal obtained by the means in a storage device, and selects whether to add an attribute signal to each pixel constituting the raster image based on the logical sum signal generated by the logical sum signal synthesis means And an attribute of each pixel based on the logical sum signal generated by the logical sum signal synthesis means. An image forming apparatus comprising: means for selecting whether or not to store a signal in a storage device; and means for storing in the storage device an attribute signal of each pixel determined to be stored in the storage device by the selection means. apparatus.   2. The image forming apparatus according to claim 1, wherein the total amount of attribute signals determined by the storage unit based on the logical sum signal stored in the storage device and whether or not to hold based on the logical sum signal is the attribute according to claim 1. A storage amount determination unit that determines whether or not the total amount of attribute signals added to all pixels by the information addition unit exceeds the total amount of the logical sum signal and the attribute signal of each pixel by the storage amount determination unit. When it is determined that the total amount of attribute signals added by the attribute information adding means described in 1 is exceeded, the logical sum signal stored by the storage means and the attribute signal of each pixel are not stored in the storage means. A restoring means for restoring the attribute signal; a storage means for storing the attribute signal restored by the restoring means in a storage device; and a logic for deleting the logical sum signal from the storage means. An image forming apparatus, comprising a signal deleting means.   An image forming apparatus for generating a drawing object by analyzing print data based on a plurality of page description languages, a means for generating a raster image based on a drawing command, and a bitmap data generated by the raster image generating means Change point obtained by attribute information addition means for adding a plurality of attribute signals representing data attributes for each pixel, and change point signal extraction means for extracting change points of bitmap data and attribute information obtained by raster image generation means Means for storing a signal in a storage device, and means for selecting whether or not to add the same attribute signal to a plurality of pixels constituting the raster image based on the change point signal generated by the change point signal extraction means; Effective for multiple pixels based on the change point signal generated by the change point signal extraction means. A means for selecting whether or not the attribute signal determined to be stored in the storage device; and a means for storing the attribute signal determined to be stored in the storage device by the selection means in the storage device. Image forming apparatus.   4. The image forming apparatus according to claim 3, wherein the total amount of attribute signals determined by the storage unit based on the change point signal stored in the storage device and whether or not to hold based on the change point signal is the attribute according to claim 3. A storage amount determination unit that determines whether or not the total amount of attribute signals added to all pixels by the information addition unit exceeds the total amount of change point signals and attribute signals of each pixel by the storage amount determination unit. When it is judged that the total amount of attribute signals added by the attribute information adding means described in 3 is exceeded, the change point signal stored by the storage means and the attribute signal of each pixel were not stored in the storage means Restoration means for restoring the attribute signal, storage means for storing the attribute signal restored by the restoration means in the storage device, and change for deleting the change point signal from the storage means An image forming apparatus, comprising a signal deleting means.   5. The image forming apparatus according to claim 1, wherein means for measuring an occurrence rate of white pixels in the bitmap data generated by the raster image generating means and pixels to which no change point signal is added. OR means based on the number of bits of attribute information added to each pixel as an attribute signal and the generation rate obtained by the white pixel occurrence rate measuring means and the change point signal occurrence rate measuring means. The total amount of attribute signals determined whether to hold based on the signal and the logical sum signal or the total amount of attribute signals determined whether to hold based on the change point signal and the change point signal is added to all pixels. Means for determining whether or not the total amount of attribute signals is exceeded, attribute signal generation method selection means for selecting a means with the smallest memory usage according to the determined result, Image forming apparatus characterized by the attribute signal generation method selected by the selecting means and a means for storing generated in the storage device attribute signal.