JP2001246794A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus in which an image can be formed at high speed even in color mode so long as a monochromatic image is formed and charged correctly. SOLUTION: In a printer function, a CPU 11 performs decomposition based on the data of PDL received through a communication interface 14 to generate data of intermediate language. Based on the value of image data, a decision is made whether an image only of K is formed or other colors are included. In case of an image only of K, rendering from intermediate language to image data, compression of data at a compressing section 16, decompression of encoded data at a decomposing section 17, and imaging at an imaging section 18 are performed only for K and not performed for other colors. Consequently, an image can be formed monochromatically at high speed even if color is designated and charged as a monochromatic image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image based on input image data or image data generated from an input page description language.

[0002]

2. Description of the Related Art In recent years, image forming apparatuses capable of forming color images have become widespread. As a configuration of such an image forming apparatus, a 4-tandem type and a 4-cycle type are typical. FIG. 5 is a schematic configuration diagram illustrating an example of a 4-tandem image forming apparatus. In the drawing, 31 is a cyan recording section, 32 is a magenta recording section, 33 is a yellow recording section, 34 is a black recording section, 35 is paper, 36 is a transport belt, 37 is a paper tray, and 38 is a paper discharge tray. The paper 35 loaded in the paper tray 37 is transported on the transport belt 36 one by one. As the paper is transported, the black recording unit 34, the yellow recording unit 33, the magenta recording unit 32, and the cyan recording unit 31
As a result, images of each color are sequentially formed on the paper 35 in a superimposed manner. After that, the formed image is fixed, and the paper 35 is discharged to the paper discharge tray 38. In addition to the configuration of such a 4-tandem image forming apparatus, various configurations have been considered, such as a configuration in which an image is formed on an intermediate transfer body by each recording unit and then transferred to a sheet.

In such a four-tandem type image forming apparatus, the recording unit must be arranged on the paper transport path, so that the apparatus becomes large. However, since images of each color can be formed only by transporting the paper. A high-speed color image can be formed.

FIG. 6 is a schematic diagram showing an example of a 4-cycle type image forming apparatus. In the figure, the same parts as those in FIG. 5 are denoted by the same reference numerals. 41 is a developing section selector, 42 is a cyan developing section, 43 is a magenta developing section, 44 is a yellow developing section, 45 is a black developing section, and 46 is an intermediate transfer drum. The developing unit selector 41 selects one of the cyan developing unit 42, the magenta developing unit 43, the yellow developing unit 44, and the black developing unit 45 to form an image on the intermediate transfer drum 46. This operation is performed four times while switching the developing unit.
After the color image is formed on the intermediate transfer drum 46, the image is transferred to the paper 35 conveyed on the conveyance belt 36,
After the fixing, the paper 35 is discharged to the discharge tray 38. In addition to such a configuration, a four-cycle type image forming apparatus employs several methods such as a method in which a sheet is wound around a drum, the drum is rotated four times, and an image of each color is formed directly on the sheet. Configuration is considered.

In such a four-cycle type image forming apparatus, four recording operations must be performed sequentially, and
Although the recording speed is lower than that of the 4-tandem type, the apparatus can be downsized.

Further, a color multifunction machine integrating the functions of a printer and a copier using the above-described image forming apparatus, and a multifunction machine having a FAX function have also been developed. I have. In such an apparatus, an image read by a scanner attached to the apparatus, an image input from an external computer or the like, and an image received by facsimile are switched, and the image is printed on paper by the image forming apparatus as described above. Has formed.

When an image to be formed is received from a host computer via a line such as Ethernet (registered trademark), the image may be received, for example, in a format described by a page description language (PDL). In such a case, when the image forming apparatus receives the PDL, the printer controller converts the data into an intermediate language that is more easily converted into image data (decompose processing), and then generates a print image from the intermediate language (rendering processing). At this time, if the image data to be printed for one page is stored in the memory, in the case of a color image or the like, a bitmap image requires an A3 size, a resolution of 600 dpi and a memory of 32 Mbytes or more.

In order to eliminate the need for preparing a large amount of memory, for example, one page is divided into a plurality of areas (bands) for each predetermined number of lines (banding processing) and compressed for each band. The method of going is used. Further, it has been considered to reduce the amount of memory by compressing and storing image data, and expanding and outputting the image data during printing.

A general banding process using compression will be described. First, as decomposer processing, the input PDL is decoded, and an intermediate language for each band is generated.
The intermediate language for each band of the page is stored in the memory.
Next, rendering is performed for each band, and image data, which is a print image, is stored in a memory. When one band of image data has been created, it is compressed and stored in memory. This is performed for all bands for one page. After the compression of one page is completed, the data is decompressed in real time by a decompressor, and image data is output to a print engine to form an image. Thus, an image can be formed without expanding one page of image data in the memory.

However, in the method of compressing and decompressing one page of image data as described above, there is a problem that each of the compression and decompression processes takes time. For example, A3
A document with a size and resolution of 600 dpi can be converted to 20 Mbits /
Even if compression and decompression processing is performed in real time at a speed of about s, it takes about 3 seconds for a black and white image and 12 for a color image.
It takes seconds. When an image is formed by receiving a PDL, a time for the decomposing process and a rendering process are required in addition to the above, so that there is a problem that it takes much time to start the printing process.

A method has been proposed in which rendering performance is improved and an image is output in real time from an intermediate language to a print engine without performing compression and decompression processing. However, the time required for the rendering process varies depending on the image data. For example, in a printing apparatus described in Japanese Patent Application Laid-Open No. Hei 8-224917, the time required for rendering for each band is estimated. An extension method has also been proposed. However, in such a system, the intermediate language and the code data are mixed, and when outputting to the print engine, it is necessary to generate the image data while switching between the intermediate language and the code data, so that the processing becomes complicated. There's a problem.

Another example is disclosed in Japanese Patent Application Laid-Open No. Hei 6-31611.
In the image forming apparatus described in Japanese Patent Application Laid-Open No. 8 (1999) -1995, there is described a technique of forming an image by changing the image forming speed when printing cannot be performed at a constant printing speed based on the amount of image information as a result of decomposing. . As a result, an image can be formed at a high speed when it does not take much time to develop the image data. However, in a four-tandem image forming apparatus as shown in FIG. 5, for example, the position of the image of each color may be slightly shifted due to a change in the image forming speed, causing a color shift, and it is difficult to adjust them. There was a problem.

As another problem, in the above-described color image forming apparatus, if image formation is started in a color auto mode or the like, even if the formed image is monochrome, it is processed as a color image. There is a problem that an image can be formed only at a speed for forming a color image. In addition, in the case of charging a copy machine or the like based on the number of prints, if a monochrome image is formed in the color mode as described above, there is a problem that the user is charged as forming a color image.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances. Even in a color mode, if an image to be formed is monochrome, high-speed image processing is performed without performing unnecessary color processing. It is an object of the present invention to provide an image forming apparatus capable of performing formation and correctly performing billing in such a case.

[0015]

According to the present invention, there is provided an image forming apparatus for forming a color image by inputting data described in a page description language or inputting image data from an image input means. The value of the image data generated from the language or the input image data is determined, and based on the result of the determination, it is determined whether or not to perform the compression / expansion processing in the compression unit and the expansion unit or the image formation in the forming unit that forms the image. At least for each control. With this, even if the setting of color is made, for example, when the image data is black and white, this is detected by judging the value of the image data, and the compression and decompression process is performed on the image of only black, or Control is performed so that an image is formed only with black. For this reason, unnecessary color processing is not performed, and only black image formation can be performed, so that an image can be formed at a higher speed than in the case of controlling as a color image. Also, when billing, assuming that the image is formed only with black,
You can be charged correctly.

For example, in the case of a configuration in which image data is compressed by a compressing unit, decompressed, and output image data is passed to the forming unit to form an image, the value of the image data is determined when the image data is generated. This eliminates the need to process unnecessary color image data in the compression process and the decompression process, and can further increase the speed. Also, the value of the image data can be determined at the time of compression, and in this case, it is not necessary to perform processing on image data of an unnecessary color for the decompression process, and the speed can be increased. In a configuration in which image data is directly input from an image input unit or the like, it is not necessary to separately determine the value of the image data. Therefore, a configuration in which the determination is performed at the time of compression is effective.

[0017]

FIG. 1 is a block diagram showing an embodiment of an image forming apparatus according to the present invention. In the figure, 1 is an image processing apparatus, 2 is a host computer group, 11 is a CPU,
12 is a CPU bridge, 13 is a main memory, 14 is a communication interface, 15 is a bus, 16 is a compression unit, 17 is a decompression unit, 18 is an image forming unit, and 19 is an image input unit.
The image processing apparatus 1 according to this embodiment receives data described in, for example, PDL from the host computer group 2 and forms an image by performing a drawing process according to PDL. Further, it has a function of forming an image based on image data read from the attached image input unit 19. Of course, a FAX function or the like may be provided in addition to the above. Further, the input from the host computer group 2 is not limited to the PDL, but may be configured to directly receive image data, for example.

The CPU 11 controls the entire image processing apparatus 1 and functions as a drawing unit and a control unit.
Rendering processing is performed in accordance with data such as PDL sent from the host computer group 2, and image data is
, And the compressed coded data is stored in the main memory 13. Further, the coded data input from the image input unit 19 and compressed by the compression unit 16 is stored in the main memory 13. Then, when outputting the image data to the image forming unit 18, the decompressing unit 17 decompresses the encoded data and outputs it. In the drawing process, image data may be directly generated from the PDL, or the image data may be generated by a rendering process after being temporarily converted to an intermediate language by a decomposing process. The image data is
The image may be generated in units of one page or in units of bands obtained by dividing an image for one page into a plurality of regions.

The CPU 11 can be configured to judge the value of the image data in the course of the drawing process for generating the image data from the PDL or for the input image data. Then, based on the determination result, the compression / decompression processing in the compression unit 16 and the decompression unit 17 is performed.
Whether or not to form an image in the image forming unit 18 is controlled for each color. For example, from the value of the image data,
It is determined whether all the values of Y (yellow), M (magenta), and C (cyan) are 0. When it is determined that all the values of Y, M, and C are 0 according to the determination result, the compression unit 16 does not perform the compression process on each of the colors of Y, M, and C, and outputs the K (black). ) Compression processing by the compression unit 16 is performed on only the color. Then, the image forming unit 18
When an image is formed by the K, the coded data of only K is decompressed by the decompression unit 17 and the output image data of K is decompressed by the image forming unit 18.
To form a black and white image. In the case of temporarily converting to an intermediate language by the decomposing process in the drawing process, the value of the image data generated in the next rendering process can be predicted in the decomposing process, and the value of the image data should be determined at this time. Thus, the rendering process can be omitted.

Further, the CPU 11 can be configured to perform a billing process at the time of image formation. Generally, the amount charged differs between the time of forming a color image and the time of forming a black-and-white image. For example, even when an image formation is instructed as a color image, if the image is formed as a black and white image by the above-described control, the charge for the monochrome image is charged.

The main memory 13 can store programs to be executed by the CPU 11 and various data. In particular, the P sent from the host computer group 2
DL data, intermediate languages, generated image data, encoded data, and the like can be stored.

The communication interface 14 communicates with the host computer group 2 and receives PDL data or image data.

The bus 15 connects the communication interface 14, the compression unit 16, and the expansion unit 17 to each other, and
CPU 11 and main memory 1 via U-bridge 12
3 is also connected. Of course, various other devices may be connected to the bus 15.

The compression section 16 compresses the image data transmitted via the bus 15 or the image data input by the image input section 19 by a predetermined compression method to generate encoded data. The decompression unit 17 generates output image data by decompressing the encoded data sent via the bus 15 according to a predetermined compression method, and outputs the output image data to the image forming unit 18.

The image forming section 18 receives the output image data generated by the decompressing section 17 and actually forms an image.
The configuration of the image forming unit 18 may be a four-tandem type shown in FIG. 5, a four-cycle type shown in FIG. 6, or another configuration. In case of 4 tandem type,
Depending on the processing speed, the expansion unit 17 or the compression unit 16 may require four channels for each color.

The image input section 19 has a scanner for reading an image on a document, an image processing section for performing image processing on the input side, and the like, and outputs input image data to the compression section 16. The image input unit 19 may be omitted.

FIG. 2 is a flowchart showing an example of the operation of the image forming apparatus according to the embodiment of the present invention.
Here, the P sent from the host computer group 2
An example of an operation when an image is formed based on DL data is shown. Note that, as drawing processing for generating image data from PDL, it is assumed that PDL data sent from the host computer group 2 is converted into an intermediate language by decomposing processing, and then image data is generated by rendering processing. In this example, it is assumed that image data is generated in band units.

When PDL data is sent from the host computer group 2, it is received by the communication interface 14, and the received PDL data is transferred to the main memory 13 via the bus 15 and the CPU bridge 12. Store.

First, in S51, the CPU 11 sets a flag C indicating whether to form a color image or a monochrome image.
FLAG is reset to 0. Thereafter, in S52, the decomposing process is performed with reference to the PDL data stored in the main memory 13 to obtain an intermediate language for one band from the PDL data.

At the point when the intermediate language for each band is generated by the decomposing process, the value of the image data of the band is determined in S53. For example, referring to the intermediate language for each band, it is determined whether or not a drawing command for each color of Y, M, and C exists in the band. This makes it possible to determine whether the band is a color image or a black-and-white image.

If the band is determined to be a color image, the flag CFLAG is set to 1 in S54, indicating that a color portion exists in the image to be formed. Then, in S55, one band of image data is generated from the intermediate language by the rendering process. The generated image data is transferred to the CPU bridge 12, the bus 15
Is transmitted to the compression unit 16 via the, and is compressed to become encoded data. The encoded data is stored in the main memory 13 via the bus 15 and the CPU bridge 12 again.

If it is determined that the band is a monochrome image, in S56, rendering processing is performed only on K, and one band of K image data is generated from the intermediate language. The generated K image data is sent to the compression unit 16 via the CPU bridge 12 and the bus 15, and is compressed to become encoded data. The encoded data is transferred to the main memory 13 via the bus 15 and the CPU bridge 12 again.
Is stored in Note that Y, M, and C are all 0.
May be stored in the main memory 13.

In S57, it is determined whether or not the above-described processing has been performed for all the bands in one page. If any unprocessed band remains, the processing is performed from S52 for that band. The processing for each band is performed in this manner, and when the processing for all the bands is completed, if the image of one page is a monochrome image, the flag CFLA is used.
The value of G remains at 0. However, the flag CFLAG has a value of 1 if there is at least one band including a color image.

When the encoded data has been created for all the bands, the image forming section
To form an image. In S58, the flag C
Determine the value of FLAG. As described above, the value of the flag CFLAG is 1 for a color image including Y, M, and C. In that case, in S59, the image forming unit 1
8 is controlled to perform color image formation. Then, in S60, the encoded data is read from the main memory 13, transferred to the decompression unit 17 and decompressed, and the obtained output image data is sent to the image forming unit 18 to form an image. At this time, if the image forming unit 18 is a four-tandem type as shown in FIG. 5, the decompression process and the image formation are performed in parallel for each of the colors Y, M, C, and K. If the image forming unit 18 is of a four-cycle type as shown in FIG. 6, the decompression process and the image formation are performed for each color in accordance with the order of the colors for image formation. In this case, charging for forming a color image is performed.

When the value of the flag CFLAG is 0, the image formed as described above is monochrome. In such a case, in S61, the startup control is performed so that the image forming unit 18 performs monochrome image formation using only K. Then, in S62, the coded data of only K is read from the main memory 13, transferred to the decompression unit 17 and decompressed, and the obtained output image data is stored in the image forming unit 1.
8 to form a black and white image. For example, the image forming unit 18
However, even in the case of the 4-tandem type as shown in FIG. 5, only the expansion processing of only K and image formation are performed, so that high-speed image formation is possible. Depending on the configuration, image data may also be required for Y, M, and C. In such a case, for example, without performing actual decompression processing by the decompression unit 17, all blank (eg, 0) data is What is necessary is just to output to the image forming part 18 as output image data. Further, for example, when the image forming unit 18 is of a four-cycle type as shown in FIG. 6, only the K image forming cycle is required, so that image formation can be performed much faster than a color image.
When an image is formed as a black and white image,
For example, even if the image formation is instructed in the color mode, it is possible to charge the user when the monochrome image is correctly formed.

In the above example, the decomposing process is performed for each band. For example, the decomposing process is performed for all the bands in advance to determine whether only K or other colors are included. Is also possible. In this case, the return destination from S57 is S53. In such a case, the image forming unit 18 is activated even after the encoded data for one page has not been collected.
The image forming unit 18 may be activated at the timing when the output to the printer unit is completed, and the decompression process by the decompression unit 17 may be started. In this case, the compression process by the compression unit 16 and the decompression process by the decompression unit 17 are performed in parallel. When the determination result is obtained by the decomposing process, a part or all of the encoded data compressed by the compression unit 16 can be directly transferred to the decompression unit 17.

In the above example, the processing is performed in band units. However, the processing is not limited to this. For example, the processing may be performed in page units.

In the above example, the case where PDL data is transmitted from the host computer group 2 has been described. In this case, the value of the image data could be determined in the process of converting the PDL into the intermediate language or the image data. For example, when image data is sent from the host computer group 2 or when image data read by the image input unit 19 is input, the value of the image data cannot be determined in the above-described conversion process. In such a case, for example, the CPU 11 may scan all the image data to make the determination. As another method, when image data is transferred to the compression unit 16, the compression unit 16 may determine. Hereinafter, an example in which the compression unit 16 determines the value of image data will be described.

FIG. 3 is a block diagram showing an example of the compression section. In the figure, 21 is an image input selection unit, 22 is a compressor, 2
3 is a code output unit, 24 is a color detection unit, and 25 is a page management unit. Image data is input to the image input selection unit 21 via the bus 15 and image data read by the image input unit 19. Image input selector 2
1 selects one according to the selection signal, and
And the image data is passed to the color detection unit 24. The selection signal is a signal for switching between operation as a printer and operation as a copier.

The compressor 22 compresses the input image data according to a predetermined encoding method, and passes the encoded data to the code output unit 23. The code output unit 23 transfers the coded data compressed by the compressor 22 via the bus 15.

The color detector 24 determines the value of the input image data. For example, it is determined whether the image data is a monochrome image of only K or a color image including the colors of Y, M, and C. Then, the result of the determination is transmitted to the CPU 11. The color detection unit 24 can perform the compression processing in the compressor 22 in parallel.

The page management unit 25 manages the start and end of one page, and outputs a one-page enable signal to the compressor 22 and the color detection unit 24.

FIG. 4 is a flowchart showing another example of the operation in the embodiment of the image forming apparatus of the present invention. Here, an example of the operation using the compression unit having the configuration shown in FIG. 3 will be described. When operating as a printer, when PDL data is sent from the host computer group 2, it is received by the communication interface 14, and the received PDL data is transferred to the main memory via the bus 15 and the CPU bridge 12. 13 and stored. Then, the CPU 11 performs a drawing process to generate image data. Alternatively, image data is received from the host computer group 2. Then, the image data is sent to the compression unit 16 via the CPU bridge 12 and the bus 15. In this case, a selection signal is input to the image input selection unit 21 so as to select the image data transmitted via the bus 15.

When operating as a copying machine,
After the image on the document is read by the image input unit 19 and subjected to predetermined input side image processing, the image data is transferred to the compression unit 1.
6 is input. In this case, a selection signal is input to the image input selection unit 21 so as to select the image data from the image input unit 19.

In step S71, the compression section 16 compresses the input image data to generate encoded data. At this time, the value of the image data is determined. That is, the image data selected by the image input selection unit 21 according to the selection signal is input to the compressor 22 and compressed to generate encoded data. The generated encoded data is output to a code output unit 2
3 and stored in the main memory 13 via the bus 15. At the same time, the image data selected by the image input selection unit 21 is also input to the color detection unit 24. The color detector 24 determines the value of the image data. For example, it can be determined whether the image is a K-only image or contains images of colors Y, M, and C. This judgment is Y,
When any of the colors M and C is detected, it can be determined that the image is a color image. The result of the determination is the CPU 11
Will be notified. The notification of the determination result may be achieved by transferring flag data of the determination result, or by adopting a method of interrupting the CPU 11 when it is determined that the image is only K, for example.

When the encoded data is created by the compression unit 16, the CPU 11 checks the result of the judgment by the color detection unit 24 of the compression unit 16 in S72. The judgment result is Y, M, C
If the result of the determination is that the image is a color image that includes the color of the image, the control unit 20 controls the image forming unit 18 to start the color image formation in S73. Then, in S74, the encoded data is read from the main memory 13, transferred to the decompression unit 17 and decompressed, and the obtained output image data is sent to the image forming unit 18 to form an image. At this time, if the image forming unit 18 is a four-tandem type as shown in FIG. 5, the decompression process and the image formation are performed in parallel for each of the colors Y, M, C, and K.
If the image forming unit 18 is of a four-cycle type as shown in FIG. 6, the decompression process and the image formation are performed for each color in accordance with the order of the colors for image formation.
In this case, charging for forming a color image is performed.

If the result of the determination is that the image is a black-and-white image of only K, in step S75, activation control is performed so that the image forming unit 18 forms a black-and-white image using only K. Then, in S76, the coded data of only K is read from the main memory 13, and the
The image data is transferred to the image forming section 18 and the obtained output image data is sent to the image forming section 18 to form a monochrome image. For example, even when the image forming unit 18 is a 4-tandem type as shown in FIG.
Since only decompression processing and image formation of only K are performed,
High-speed image formation is possible. Depending on the configuration, Y, M,
In some cases, image data is also required for C. In such a case, the actual decompression process by the decompression unit 17 does not need to be performed, and all blank (for example, 0) data is output as image data. Output to Also,
For example, when the image forming unit 18 is a four-cycle type as shown in FIG. 6, only the K image forming cycle is required, so that image formation can be performed much faster than a color image. When an image is formed as a black-and-white image in this way, for example, even if the image formation is instructed in the color mode, it is possible to charge for the case where the black-and-white image is correctly formed.

Thus, the host computer group 2
From the image input unit 19
It is also possible to determine the value of the image data and switch between color or black and white image formation based on the result of the determination with respect to the image data read in step (1). Thus, when the image to be formed is black and white, the speed of the decompression process and the image forming process can be increased, and the billing for black and white can be correctly performed. Of course, even when PDL data is sent from the host computer group 2,
If the image data after the drawing process is transferred to the compression unit 16, the image data can be determined. In the case of a black and white image, the rendering process and the compression process are performed. Speed can be increased.
In the above example, when the value of the image data at the time of decomposition is determined, for example, when the PDL itself is subjected to the ROP process (overwrite or the like), the color image portion is lost and the image becomes a monochrome image. However, the decomposing process may determine that the image is a color image. However, in the configuration in which the determination is made with reference to the value of the image data as in this example, such erroneous determination does not occur, and the processing of the color image or the monochrome image can be switched accurately.

In the configuration of the compression section 16 shown in FIG. 3, the function of the color detection section 24 is to determine whether or not there is only K and whether or not there is no K and all 0 images are present. It is also possible to have a function to perform. For example, when processing is performed for each band, there is a blank band in which no image exists in the band. By detecting such a band and generating all white (0) data for the band without performing the decompression processing, and passing the data to the image forming unit 18, the decompression processing is omitted to further increase the speed. Is possible. Such processing can be similarly applied to the case where the value of the image data is determined at the time of the above-described decomposing processing. In this case, the rendering processing and the compression processing are not performed on the blank band, and the speed can be further increased. is there.

In each of the above examples, it is assumed that the value of the image data is determined for each page.
The present invention is not limited to this. For example, when the Nin1 function for forming an N-page image on one sheet or the double-sided function is used, a value is determined for a plurality of pages of image data recorded on one sheet. can do.

In each of the above examples, the value of the image data is determined based on whether the image is a black and white image of only K or Y, M, C
Although it is determined whether the image is a color image including a color such as a color, the image is not limited to this.
Similar effects can be obtained.

Further, the present invention is applicable to a configuration in which the compression and expansion are not performed without providing the compression unit 16 and the expansion unit 17. For example, the CPU 11 determines the value of the image data at the time of the decomposing process, or the CPU 11 directly refers to the value of the image data to make a determination. If the image is determined to be a monochrome image, the image forming unit 18 determines the image as a monochrome image. What is necessary is just to control so that an image forming process may be performed. As a result, it is possible to realize high-speed operation and accurate billing.

[0053]

As is apparent from the above description, according to the present invention, the value of the image data is determined, and the compression / expansion processing of the image or the image formation by the forming means for forming the image is performed according to the determination result. Since whether or not to perform is controlled at least for each color, for example, for a black-and-white image input in the color mode, the processing is speeded up by performing compression / expansion processing only on black, or an image is formed at high speed only with black be able to. In addition, such determination of the value of the image data is performed at the time of the decomposing process or at the time of the compression process, and the process of the determination is not inserted separately, so that the value of the image data is determined efficiently. be able to. Further, even in the color mode, since a black and white image is formed in black and white, even if the user erroneously outputs a black and white document in the color mode, the black and white image can be accurately charged. is there.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a flowchart illustrating an example of an operation of the image forming apparatus according to the exemplary embodiment of the present invention.

FIG. 3 is a block diagram illustrating an example of a compression unit.

FIG. 4 is a flowchart showing another example of the operation in the embodiment of the image forming apparatus of the present invention.

FIG. 5 is a schematic configuration diagram illustrating an example of a 4-tandem-type image forming apparatus.

FIG. 6 is a schematic configuration diagram illustrating an example of a 4-cycle type image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image processing apparatus, 2 ... Host computer group, 11 ...
CPU, 12 ... CPU bridge, 13 ... main memory,
14 communication interface, 15 bus, 16 compression section, 17 expansion section, 18 image forming section, 19 image input section, 21 image input selection section, 22 compressor, 23 code output section, 24 ... Color detector, 25 ... Page manager, 31 ...
Cyan recording section, 32 magenta recording section, 33 yellow recording section, 34 black recording section, 35 paper, 36 transport belt, 37 paper tray, 38 discharge tray, 41 developing section selector, 42 ... Cyan developing unit, 43 magenta developing unit, 44 yellow developing unit, 45 black developing unit, 46 intermediate transfer drum.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) 9A001 F-term (Reference) 2C087 AA03 AA15 AB05 AC08 BB10 BB20 BC02 BD01 BD12 BD13 BD35 BD40 BD42 CB13 DA01 DA02 5B057 BA02 CA01 CB01 CE16 CG01 DB02 DB06 5C077 LL18 MP08 NP07 PP27 PP28 PP33 PP43 PQ08 RR21 SS02 TT02 TT06 5C078 AA04 AA09 CA02 DA01 DA02 5C079 HB03 KA08 LA26 PA02 PA03 9A001 BB06 EE04 HH23 HH31 KK42

Claims (8)

[Claims] 1. An image forming apparatus for forming a color image from a page description language, a drawing unit for generating image data of each color from the page description language and determining a value of the image data of each color, Compression means for encoding the generated image data to generate coded data, decompression means for decoding the coded data to generate output image data, and forming an image for each color unit based on the generated output image data An image forming apparatus comprising: a control unit configured to control, for each color, whether or not to perform a compression / expansion process in the compression unit and the expansion unit based on a determination result in the drawing unit. 2. An image forming apparatus for forming a color image from a page description language, a drawing unit for generating image data of each color from the page description language, and a value of the image data of each color generated by the drawing unit is determined. Compression means for encoding the image data and generating coded data,
Decompression means for decoding the coded data to generate output image data, forming means for forming an image for each color based on the generated output image data, and decompression processing in the decompression means based on the judgment result in the compression means An image forming apparatus having control means for controlling whether or not to perform for each color. 3. An image forming apparatus for forming a color image based on image data input from an image input means, determining an input image data value of each color, and encoding and encoding the input image data. Compression means for generating data; decompression means for decoding the encoded data to generate output image data; forming means for forming an image for each color based on the generated output image data; An image forming apparatus, comprising: control means for controlling whether or not to perform the expansion processing in the expansion means for each color. 4. An image forming apparatus for forming a color image on the basis of input image data, a forming means for forming an image for each color based on the image data, and determining a value of the input image data of each color. An image forming apparatus comprising: a control unit that controls, for each color, whether or not to form an image in the forming unit based on the determination result. 5. The image forming apparatus according to claim 1, wherein the control unit performs a charging process in accordance with a color for forming an image by the forming unit. 6. The drawing means judges the value of the image data in band units for each predetermined number of lines, and the control means controls the decompression means so as to perform at least expansion processing in band units. 2. The method according to claim 1, wherein
An image forming apparatus according to claim 1. 7. The compression unit determines the value of the image data in band units with a predetermined number of words, and the control unit controls the expansion unit to perform at least expansion processing in band units. 3. The method according to claim 2, wherein
Alternatively, the image forming apparatus according to claim 3. 8. The image processing apparatus according to claim 1, wherein said control means controls whether to form an image in said forming means based on a determination of a value of image data. Item 8. The image forming apparatus according to any one of Items 7.