JPH11320978A - Color image forming equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the printing speed of a monochrome page. When converting print data from a host computer to an intermediate code, a command analysis module determines whether or not a color is used. If a color is not used, a bitmap generation module is used. This causes the engine 19 to perform only monochrome development. Alternatively, when the command analysis module 12 converts print data from the host computer 1 into an intermediate code, the command analysis module 12 determines whether or not the print data includes RGB data. On the other hand, a process of performing color matching, under color removal, black plate generation, and conversion into CMYK data suitable for the engine 19 is performed.
From the processing result, it is determined whether or not the color is used. If the color is not used, the bitmap generation module 14 causes the engine 19 to perform only the black and white development.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color image forming apparatus such as a color printer and a digital color copying machine.

[0002]

2. Description of the Related Art For example, a color print system includes a host computer such as a personal computer and a color printer such as a color laser printer, and performs the following operations.

That is, a host computer creates a document composed of characters, graphics, photographs, and the like by operating a keyboard or the like using application software (hereinafter referred to as “application software”), and prepares the document using printer driver software (hereinafter referred to as “application software”). A page description language (PD)
After converting the data into the data of L) (print data), the data is transferred to a color printer.

On the other hand, a color printer interprets print data from a host computer and converts an original document on a memory into a bitmap image for each color of C (cyan), M (magenta), Y (yellow), and K (black). And print it on paper by the printing means (engine).

[0005] Documents handled by such a printing system include a page in black and white only and a page in color containing a colored graph or the like. Generally, a color printer of one drum (photoreceptor drum) is CM
Since development is performed for each color of YK, the speed is lower than that of black and white printing.

Therefore, in a conventional color print system, when printing a document in which color and black and white are mixed, the host computer determines whether each page is a black and white page by a printer driver, and determines the result. By adding the indicated information to the print data (PDL data) of each page and transferring it to a color printer, the color printer generates a black-and-white only bitmap image when printing a black-and-white only page. The printing speed of black and white pages can be improved.

When printing a monochrome document on a color printer, there are many methods in which a user is explicitly instructed to print in a monochrome mode by using a function of a printer driver.

In general, R (red), G (green), and B (blue) are designated as color colors. However, since color printers have different color characteristics for each device, color data is used for RGB data as print data. The data is converted into CMYK data by performing processes such as matching, undercolor removal, and black plate generation. In this case, even if the RGB data is converted to CMYK data even if it is color data, only K (black and white) data may be obtained. Conventionally, it is not possible to determine whether a page will be black and white only from RGB data only.
It was processed as a color document.

[0009]

As described above, in the conventional color printing system, when printing a document in which color and black and white are mixed, the host computer needs a printer driver in advance to improve the printing speed of black and white pages. Was used to check whether color was used for each page (whether or not a page was black and white only). However, this method requires analyzing the document data once, which is a factor that degrades performance. As a result, the printing speed decreases.

[0010] When a monochrome printer is to be printed by a color printer, it is necessary for the user to explicitly instruct printing in the black and white mode, which puts a burden on the user. On the other hand, when the host computer uses a printer driver to convert a color document into RGB data as RGB data, the process of color matching, undercolor removal, and black plate generation that match the color characteristics of the printer device is usually performed in the color printer. Is converted to a CMYK value.

For example, when the maximum density is 256 and R = 12
Consider printing a gray document that is close to approximately 50% density, such as 6, G = 127 and B = 128. Many printer devices cannot express the difference of (1/256)% density. Therefore, as a result of converting to CMYK,
It is assumed that the density is approximated to C = M = Y = 0 and K = 50. In this case, after all, only K is used, so that the page can be regarded as a monochrome page. However, since the host computer determines that the page is a color page by the printer driver, color processing is performed, and the printing speed also decreases. Leads to.

When a black-and-white document is processed as color in the above-described manner, bitmap images of each color of CMYK are generated. However, no bitmap image for CMY is finally generated. Is not written,
Since only data indicating colorless is written, the memory (buffer) is originally wasteful and should be used for another purpose.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to improve the printing speed of a monochrome page in a color image forming apparatus.

[0014]

SUMMARY OF THE INVENTION The present invention provides an intermediate code converting means for temporarily converting print data sent from a host device into an intermediate code, and a storing means for storing the intermediate code converted by the means in a buffer. A color image forming apparatus comprising: a bitmap generating unit configured to read an intermediate code stored in the buffer to generate a bitmap image; and a printing unit configured to print the bitmap image generated by the unit on a sheet. In order to achieve the above object, the following means are provided.

According to a first aspect of the present invention, when print data from a higher-level device is converted into an intermediate code by an intermediate code conversion unit, a color use presence / absence judgment unit for judging whether or not a color is used is provided. When it is determined that the color is not used, a black-and-white development instructing means for causing the printing means to perform only black-and-white development is provided.

According to a second aspect of the present invention, in the color image forming apparatus of the first aspect, when it is determined that the color is not being used by the color use presence / absence determining means, three colors for cyan, magenta and yellow are used. The two bitmap generation buffers are also provided with a buffer allocating means for allocating as a black bitmap generation buffer.

According to a third aspect of the present invention, when the print data from the host device is converted into an intermediate code by the intermediate code conversion means, it is determined whether or not the print data includes red, green, and blue color data. A data discriminating means for discriminating, and if the discriminating means determines that color data of red, green, and blue are included, color matching suitable for the printing means, under color removal, Color conversion means for performing black plate generation and converting the color data into cyan, magenta, yellow, and black color data; and color use determining means for determining whether or not a color is used based on the processing result of the means. If the means determines that the color is not used, the black-and-white development instructing means causes the printing means to perform only black-and-white development. It is those provided.

According to a fourth aspect of the present invention, in the color image forming apparatus of the third aspect, when it is determined that the color is not used by the color use presence / absence determining means, three colors for cyan, magenta, and yellow are used. The two bitmap generation buffers are also provided with a buffer allocating means for allocating as a black bitmap generation buffer.

[0019]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing an example of a color print system embodying the present invention.

This color printing system comprises a host computer 1 and a color printer 10.

The host computer 1 is a higher-level device such as a personal computer, and creates a document (electronic document) 2 composed of characters, graphics, photographs, and the like by using an application software 3 by operating a keyboard and the like. After being converted into page description language (PDL) data (print data) 5 by the printer driver 4, the data is transferred to the color printer 10.

The color printer 10 is a color image forming apparatus, and reads print data (command) 5 from the host computer 1 into an input buffer 11. Thereafter, the command analysis module 12 sequentially reads and analyzes the commands from the input buffer 11, converts a part of the commands into an intermediate code that is information necessary for generating a bitmap image, and stores the intermediate code in the intermediate buffer 13.

If the command read from the input buffer is a command for instructing the start of printing (print job), C (cyan), M ( Magenta), Y
(Yellow) and K (black) bitmap images for cyan, magenta, yellow, and black
Bitmap generation buffers 15, 16, 17, 1
8 and generate them on the engine (printing means)
19 to print on paper.

The functions of the command analysis module 12 and the bitmap generation module 14 are realized by a microcomputer (not shown). Each unit in the color printer 10 shown in FIG. 1 includes an intermediate code conversion unit, a storage unit, a bitmap generation unit, a printing unit, a color presence / absence determination unit, a black and white development instruction unit, and a buffer allocation unit. , Data discriminating means and color converting means.

Next, for explanation of the command analysis module 12, an example of PDL data is shown in FIG. Note that this is merely an example for explaining the embodiment, and is not directly related to the present invention. In this example, a document composed of colored characters, colored rectangles, black and white images, and color images is handled.

First, a command (job start command) for instructing the start of a print job is transferred from the host computer 1, and thereafter, a command (page start command) for instructing the start of the first page, characters and characters that actually constitute a document, The information of the color, the rectangle, and the image continues, and one page ends by a command (page end instruction) indicating the end of the page. In the case of a plurality of pages, a command sequence similar to that of the first page continues, and is finally completed with a command (job end instruction) for instructing the end of the print job.

FIG. 3 shows the command analysis module 1 of FIG.
3 is a flowchart illustrating an example of a process according to a second embodiment. The command analysis module 12 first reads the print data (input data) from the input buffer 11, and if it is a page start command, initializes a flag (color use flag) indicating whether or not the page is a color page to "0". Become

The print data read from the input buffer 11 is a color setting command, and CMYK color data (CM
If the color information specifies the color information (YK data), it is determined whether the color is used by taking the sum of cyan (C), magenta (M), and yellow (Y). That is, if a color is used, the color use flag is set to "1".

If the print data read from the input buffer 11 is a color image drawing command, the color use flag is set to "1" unconditionally. At this time, if the image has a size such that the performance degradation can be ignored, it may be checked whether or not the color is actually used in the data sequence constituting the image in the same manner as the color setting instruction. .

If the print data read from the input buffer 11 is a page end command, the process proceeds to a bitmap generation process by the bitmap generation module 14. If the print data read from the input buffer 11 is not a page end command, the print data is converted into an intermediate code, which is the minimum information necessary for generating a bitmap image, and is stored in the intermediate buffer 13.

Here, the processing enclosed by the broken line in FIG.
This is a process necessary to carry out the invention of claim 3 or 4. This is because the color setting instruction is CMYK color data (C
If the color information specifies RGB color data (RGB data) other than (MYK data)
A method for determining whether or not data is included, and when the data is included, performing color matching, undercolor removal, and black plate generation suitable for the engine 19 on the color information and converting the color information into CMYK data. It is.

When it is determined from the conversion result that the color is used, that is, whether the color is used is determined by taking the sum of CMY, and the sum is non-zero, that is, the color is used. If so, the color use flag is set to "1". Even if the RGB value is a value indicating a color, if CMY is 0 after CMYK conversion (when CMY is not used), the color use flag is not set to “1”.

FIG. 4 is a flow chart showing an example of the processing (subroutine of the bitmap generation processing in FIG. 3) by the bitmap generation module 14 in FIG. In this process, when the print data read from the input buffer 11 is a page end command or the like, a bitmap image is generated (bitmap development) while reading out the intermediate codes stored in the intermediate buffer 13 so far. is there.

The command analysis module 12 first checks the color use flag. If the color is not used in the page, the color use flag remains initialized to “0” by the processing of FIG. 3, so that only the K bitmap image needs to be generated. This is the essence of the present invention in that high-speed printing can be realized in the case of a monochrome page even in the case of a document where both the document and the monochrome (monochrome) exist.

In order to generate a bitmap image, a bitmap generation buffer for that purpose is required. However, in the case of only K, only one of the CMYK bitmap generation buffers is required. If there is a bitmap generation buffer for the color that has been developed and is no longer needed even during printing, a K bitmap image is generated on the bitmap generation buffer.

That is, by sequentially searching the developed bitmap generation buffer and generating a K bitmap image on the bitmap generation buffer, even if printing is in progress, the bit after the next page is read. A map image can be generated, and printing can be performed at high speed when monochrome pages are consecutive.

The color printer 10 in this embodiment
According to the above, the host computer 1 performs the processes shown in the following (1) and (2),
Eliminates the need to determine whether the page to be printed is color or black and white. In addition, the printing speed of a black and white page can be improved without making the user aware of whether the document is color or black and white.

(1) Even when the print data from the host computer 1 does not include a special instruction indicating whether the page is a color page or a monochrome page, the print data from the host computer 1 is converted into an intermediate code. It is determined whether or not color is used. If color is not used, that is, if the page is only black and white, the engine 19 is caused to perform only black and white development.

(2) When converting print data from the host computer 1 into an intermediate code, it is determined whether or not the print data includes red, green, and blue color data. The print data is subjected to color matching, under color removal, and black plate generation suitable for the engine 19, and is converted into cyan, magenta, yellow, and black color data, and the color is used from the processing result. It is determined whether or not the color is used, and if the color is not used, the engine 19 performs only the black and white development.

If it is determined that the colors (1) and (2) are not used, and if the colors are not used, three colors for cyan, magenta, and yellow are used.
One bitmap generation buffer can also be allocated as a black bitmap generation buffer. For example, when two black and white pages are consecutive, the first page can be allocated to a monochrome bitmap generation buffer, and the second page can be allocated to a cyan bitmap generation buffer. As a result, it is possible to generate the bitmap image of the second page while developing and discharging the first page, and it is possible to improve the printing speed when the black and white pages continue.

Although the embodiment in which the present invention is applied to a color printer has been described above, the present invention is not limited to this, and can be applied to other color image forming apparatuses such as a digital color copying machine. The present invention is also applicable to an image forming controller of a color image forming apparatus.

[0042]

As described above, according to the color image forming apparatus of the first aspect of the present invention, the print data from the host device includes a special instruction indicating whether the page is a color page or a monochrome page. Even if there is no, when converting print data from a higher-level device into an intermediate code, it is determined whether or not color is used, and if no color is used, the printing means performs only black-and-white development. There is no need for the device to use the printer driver to determine whether the page to be printed is color or black and white. In addition, the printing speed of a black and white page can be improved without making the user aware of whether the document is color or black and white.

According to the color image forming apparatus of the second aspect of the present invention, in addition to the same processing as the first aspect of the present invention, when no color is used, three colors of cyan, magenta and yellow are used. Since the bitmap generation buffer can also be allocated as a black bitmap generation buffer, the printing speed in the case of continuous black and white pages can be improved in addition to the same effect as the first aspect of the present invention.

According to the color image forming apparatus of the present invention, when the print data from the host device is converted into an intermediate code, it is determined whether the print data includes red, green, and blue color data. Is determined, and if it is included, the print data is subjected to color matching suitable for the printing means, undercolor removal, black plate generation, and converted to cyan, magenta, yellow, and black color data. It is determined whether or not color is used from the processing result, and if no color is used, the printing means performs only black-and-white development, so that the same effect as the first aspect of the invention can be obtained.

According to the color image forming apparatus of the fourth aspect of the present invention, in addition to the same processing as the third aspect of the present invention, when no color is used, three colors of cyan, magenta and yellow are used. Since the bitmap generation buffer can also be assigned as the black bitmap generation buffer, the same effect as the second aspect of the invention can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a color print system embodying the present invention.

FIG. 2 is a diagram illustrating an example of PDL data for explanation of a command analysis module 12 in FIG. 1;

FIG. 3 is a flowchart showing an example of processing by a command analysis module 12 in FIG. 1;

FIG. 4 is a flowchart illustrating an example of a process (a subroutine of the bitmap generation process in FIG. 3) by the bitmap generation module 14 in FIG. 1;

[Explanation of symbols]

 1: Host computer 2: Electronic document 3: Application software 4: Printer driver 5: Print data 10: Color printer 11: Input buffer 12 Command analysis module 13: Intermediate buffer 14: Bitmap generation module 15: For bitmap generation for cyan Buffer 16: Magenta bitmap generation buffer 17: Yellow bitmap generation buffer 18: Black bitmap generation buffer 19: Engine

Claims (4)

[Claims] An intermediate code converting means for temporarily converting print data sent from a host device into an intermediate code, an accumulating means for accumulating the intermediate code converted by the means in a buffer, and an accumulating means for accumulating the intermediate code in the buffer. A color image forming apparatus comprising: a bitmap generation unit that reads an intermediate code to generate a bitmap image; and a printing unit that prints the bitmap image generated by the unit on a sheet. When converting to an intermediate code by the intermediate code conversion means, color use presence or absence determination means to determine whether or not a color is used,
A color image forming apparatus, comprising: a black-and-white development instructing unit that causes the printing unit to perform only black-and-white development when it is determined that the color is not used. 2. The color image forming apparatus according to claim 1, wherein when the color use determining unit determines that no color is used, three bitmaps for cyan, magenta, and yellow are used. A color image forming apparatus comprising: a buffer allocating unit that allocates a generation buffer as a black bitmap generation buffer. 3. An intermediate code conversion unit for temporarily converting print data sent from a higher-level device into an intermediate code, a storage unit for storing the intermediate code converted by the unit in a buffer, and an intermediate code stored in the buffer. A color image forming apparatus comprising: a bitmap generating unit that reads an intermediate code to generate a bitmap image; and a printing unit that prints the bitmap image generated by the unit on a sheet. A data discriminating unit for discriminating whether or not the print data includes red, green, and blue color data when the intermediate data is converted into an intermediate code by the intermediate code converting unit; If it is determined that color data is included, the print data Color conversion means for performing color matching, undercolor removal, and black plate generation suitable for the printing means to convert the color data into cyan, magenta, yellow, and black color data; Means for determining whether or not color is used, and black-and-white development instructing means for causing the printing means to perform only black-and-white development when the means determines that color is not used. Characteristic color image forming apparatus. 4. The color image forming apparatus according to claim 3, wherein if the color use determining unit determines that no color is used, the three bit maps for cyan, magenta, and yellow are used. A color image forming apparatus comprising: a buffer allocating unit that allocates a generation buffer as a black bitmap generation buffer.