JP3120981B2 - Image processing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an image processing method for handling digital image information in a page description language, and particularly includes a conversion process such as a density conversion and a development process on a bit plane. It relates to speeding up image processing.

[Prior Art] In recent years, with the cost reduction of page printers such as laser beam printers (LBPs), a programming language based on a page description language capable of expressing various character fonts and figures has been developed. One having a translation function of the page description language has been developed.

On the other hand, as a printer, a multi-value printer for expressing one dot in multiple gradations has been developed from a so-called binary printer expressing only dots in black, and a color printer capable of expressing colors has been developed and put into practical use. . Under such a background, a printer compatible with a page description language capable of handling a multi-tone image such as a photographic image or a color image is being proposed.

In such a conventional printer, image information described in a page description language in a host computer is sent to the printer. The sent page description language is sequentially decoded by a predetermined CPU.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, the CPU of the printer sequentially converts the editing information and the density information from the host side into the image developed in the page memory based on the screen configuration information table. Since a video signal is obtained by reading and performing a conversion process, for example, when a full-color image is handled, when each of the RGB colors has a depth of 8 bits, when each of the RGB colors has a depth of 8 bits, when the A4 size is 400 dots / inch, the entire size is obtained. It had a disadvantage that the processing time was enormous, about 48 Mbytes.

Also, in order to enable the density based on the density information from the host to correspond to the difference in output characteristics based on the various recording methods as described above, it is desirable that the density can be easily and quickly converted. I was

The present invention is to solve the above-mentioned problem,
An object of the present invention is to perform high-speed conversion processing corresponding to an image type and development processing into a bitmap for digital image information in a page description language.

[Means for Solving the Problems] The present invention has the following configuration as one means for achieving the above object.

That is, an image processing method according to the present invention is an image processing method for an image forming apparatus that forms an image based on digital image information in a page description language, and includes a digital image in a page description language input from an external device. Holding information, preliminarily storing a plurality of conversion processing conditions corresponding to the type of image, and performing conversion processing according to the type of image indicated by the stored digital image information from the plurality of stored conversion processing conditions An output image is developed on a bit plane while performing conversion processing on the digital image information using a condition.

An image processing method for an image forming apparatus that forms an image based on digital image information in a page description language, wherein control information in a bitmap format is developed based on input digital image information in a page description language. The digital image information is held in a one-to-one correspondence with each pixel of the output image, and a plurality of conversion processing conditions corresponding to the type of the image indicated by the digital image information are held in advance. A conversion process is performed on an image represented by the digital image information using a conversion process condition selected from a plurality of conversion process conditions.

[Embodiment] FIG. 2 is a configuration diagram of an embodiment apparatus when the present invention is applied to a color copying machine. For convenience of explanation, a printer which handles two types of text information such as characters and graphic information such as images is considered as the type of image in this embodiment. In the figure, the image processing device 80 includes an interface unit 1000 and a recording unit 2000.
The digital image information in the color page description language transferred from the host computer 1 is subjected to various controls such as storage, decoding, and synthesis in the interface unit 1000, and the data in the page memory is recorded in synchronization with the printer unit.
And print it there.

The color image data from the interface unit 1000
The laser processing is finally performed after the PWM processing and the like are performed. The laser light modulated according to the image data is scanned at high speed by a polygon mirror 2289 rotating at high speed, reflected by the mirror 2290, and performs dot exposure corresponding to the image on the surface of the photosensitive drum 2900. One horizontal scan of the laser beam corresponds to one horizontal scan of the image, and has a width of 1/16 mm in this embodiment. on the other hand,
Since the photosensitive drum 2900 is rotating at a constant speed in the direction of the arrow, the planar image is successively exposed by the laser beam scanning in the main scanning direction and the constant speed rotation of the photosensitive drum 2900 in the sub-scanning direction. The photosensitive drum 2900 is uniformly charged by a charger 2297 prior to exposure, and forms a latent image by exposing the charged photoconductor to light. A latent image based on a predetermined color signal is visualized by developing devices 2292 to 2295 corresponding to a predetermined color.

For example, considering the first document exposure scanning in the color reader, first, a dot image of the yellow component of the document is exposed on the photosensitive drum 2900, and is developed by the yellow developing device 2292. Next, this yellow image is transferred onto the paper wound on the transfer drum 2296 at the contact point between the photosensitive drum 2900 and the transfer drum 2296 by the transfer charger.
Due to 98, a yellow toner image is transferred and formed. The same process is repeated for M (magenta), C (cyan), and Bk (black), and a color image is formed by four-color toner by superimposing the images on paper.

FIG. 3 is a diagram showing, in particular, the inside of the interface unit 1000 and the connection relationship between it and the host computer 1 in the color copying machine shown in FIG. In FIG. 3, a page description language sent from the host computer 1 via a standard interface such as GP-IB or SCSI is sequentially decoded by a CPU 208 on a translation unit 203 described in detail later. Each piece of editing information stored in the screen configuration information table 100 (FIG. 1) inside the translating unit 203 is sequentially rewritten by the CPU 208. When editing is completed and a print request is made, various image processing such as coordinate information, characters, graphics, and density are performed on graphic data and text data in synchronization with the video clock CLK 209 generated from the memory driver 204. This is performed based on the screen configuration information table 100 to be transmitted to the memory driver 204 in real time. The full-color image information developed on the page memory 205 is the raster scan address AR synchronized with the recording unit 2000 and the printer driver 206.
By giving it as an address of the page memory 205,
Read as a raster image.

The memory driver 204 generates an address AD for recording video data corresponding to the position information from the translation unit 203 in the page memory 205, and records the address AD in the RGB page memory 205, respectively. The page memory 205 is configured in a so-called bit map format in which pixel positions on the output paper and each bit of the memory correspond one-to-one, and one pixel has a number of bits corresponding to the expression capability of the printer. For example, if the printer is R.
When each of the GB signals has an expression capability of 256 gradations, the page memory 205 has a depth of 8 bits per pixel for each color signal.

The translation unit 203 receives editing information other than video data, such as drawing, characters, and drawing information, from the host computer 1. These pieces of editing information are written in a screen configuration information table 100 described later in a bitmap format so as to correspond one-to-one to pixels of the page memory 205.

The full-color image information developed on the page memory 205 is stored in the raster memory address AR synchronized with the recording unit 2000 by the printer driver 206 from the page memory 205.
Is read out as a raster image. The printer driver 206 stores the page memory 2
Processing corresponding to the recording unit 2000 is performed on the image data from 05. For example, a YMC signal of a complementary color is generated from an RGB signal, or a sum signal is generated by performing UCR processing. Recorder 2
As a specific system of 000, it can be realized by various systems such as an electrophotographic system, a thermal transfer system, and an ink jet system.

In this way, printing is performed by combining the character, the graphic, and the document image.

Note that information on density conversion in the translation unit 203 is provided from the host computer 1, that is, a case where a density change according to preference is positively given, and a case where density conversion characteristics according to a difference in the method of the recording unit 2000 are used. In some cases, density conversion is performed independently of the host computer 1.

Further, the translation unit 203 will be described. In FIG. 1, graphic information sent from the host computer 1 in the form of a page description language by a standard interface such as GP-IB or SCSI is stored in the graphic memory 101 in the form of bit image or vector information. Is stored. In the text memory 103, a document file (hereinafter, referred to as a text file) from the host computer 1 is stored in the form of a code corresponding to a character. The screen configuration information table 100 is, for example, a table on a RAM. The contents stored in the screen configuration information table 100 are sequentially rewritten by the CPU 208 based on information, density, and coordinate information of edited characters, graphics, or images sequentially sent from the host computer 1 side.

When the editing is completed and a print request is made, various image processing such as coordinate information, characters, graphics, and density are performed on the graphic data and text data in synchronization with the video clock CLK 209 generated from the memory driver 204. The processing is performed based on the configuration information table 100 and transmitted to the memory driver 204 in real time. The full-color image information developed on the page memory 205 is read out as a raster image by giving the raster scan address AR synchronized with the recording unit 2000 as the address of the page memory 205 from the printer driver 206.

The graphics memory 101 stores graphics data sent from the host computer 1 as bit images or vector information. Text memory
In 103, a text file from the host computer 1 is stored in a code corresponding to the character. The screen configuration information table 100 is tabulated on a RAM, for example. As described above, the contents of the screen configuration information table 100 are sequentially transmitted to the bus 106 by the CPU 208 based on the information, density, and coordinate information of edited characters, graphics, or images sequentially transmitted from the host. Rewritten via

Further, when editing is completed and a print request is made, in synchronization with the video clock CLK 209 from the memory driver 204,
The contents of the graphic memory 101 or the text memory 103 are sent to the memory driver 204 via the graphic processing unit 102 or the code image conversion unit 104 in serial for each pixel. At this time, the screen configuration information table 100
Based on this information, one of the video data in the character area and the graphic area is selected by the γ unit 109.

The γ section 109 will be described in detail with reference to FIG. In the figure, when a print request is received, graphic information from the graphic processing unit 102 is input from the bus 107, and text information from the code image conversion unit 104 is input from the bus 108. These two video signals are sent to selector 301
Are connected to one input terminal A and the other input terminal B. These two pieces of video data are synchronized with the select signal 304 of the selector 301 and the video clock CLK 209 from the memory driver 204, and correspond to the select signal 304 read from the screen configuration information table 100 in FIG. Either one is selected according to. That is, when the select signal 304 is "1", the A terminal of the selector 301, that is, the graphics data, is selected, and when the select signal 304 is "0", the B terminal of the selector 301, that is, the text data is selected. You.

The video data selected by the select signal 304 is converted by an LUT (lookup table) 302 according to the output characteristics of the output device of the recording unit 2000. At this time, the graphic / TEXT signal (= select signal 30) transmitted in synchronization with the video information from the screen configuration information table 100 in FIG.
4) is connected to the upper address of the LUT 302, and density conversion specific to text data and graphic data is performed for each pixel.

Further, the upper address 305 for the LUT 302 also allows the CPU 208 to set the color-sequentially, that is, the R.R.
Different density conversion for each GB is also possible.

Thus, density-converted graphic and text data (video data) written into the page memory 205 via the memory driver 204 shown in FIG.
Is read as a raster image by giving a raster scan address AR synchronized with the recording unit 2000 as an address of the page memory 205 from the printer driver 206 as full-color image information. Next, a full-color output image can be obtained by performing processing according to the recording unit 2000 in the printer driver 206.

FIG. 5 is a control flowchart of the CPU 208 of the translation unit 203.

When the command data sent from the host computer 1 is received, it is determined in step S1 whether the command is a print command. If the command is craft data,
After the determination in S5, the bus 106 is released to the graphic memory 101 in step S6, and the graphic memory 101 is released.
Write video data to Then, in step S7, a graphic code is written to the screen configuration information table 100 based on the predetermined address information. Similarly, when the command is text data, in step S8 the bus 10
6 is released to the text memory 103, video data is written to the text memory, and a text code is written to the screen configuration information table 100 in step S9 based on predetermined address information. After them, return to the MAIN routine.

If the command from the host computer 1 is a print command, all the memories, that is, the screen configuration information table 100 and the graphic memory 101 in FIG.
The clock VCLK is changed to the video clock CLK209 so that the text memory 103 can be accessed from the memory driver 204 side.
Switch to. Thereafter, in step S3, the upper address 305 of the LUT 302 is switched to correspond to each color. At this time, in the LUT 302, the density conversion operation described with reference to FIG. 4 is performed by hardware independently of the control of the CPU 208. Next, the above-described sequence is repeated until all colors are completed by the determination in step S4.

In this way, the density conversion can be performed in real time according to the graphic video data and the text data without the intervention of the CPU 208, so that a high-speed, high-quality image processing apparatus can be provided. In other words, before expanding to full page memory, the CP
Since the density conversion can be performed in real time according to the output characteristics of the output device without using the U, it is possible to provide a high-speed to high-quality output image at a low price.

[Effects of the Invention] As described above, according to the present invention, conversion processing corresponding to an image type and development processing into a bitmap are performed at high speed on digital image information in a page description language. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram of a central portion of an image processing apparatus according to an embodiment of the present invention, FIG. 2 is an overall block diagram when the present invention is applied to a color copying machine, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a block diagram of the .gamma. Part of the apparatus of FIG. 1, and FIG. 5 is a flowchart of control according to the embodiment of FIG. In the figure, 100: image configuration information table, 101: graphic memory, 102: graphic processing unit, 103: text memory, 104: code image conversion unit, 105: font
ROM, 106 ... bus, 107 ... graphic data, 108 ...
... text data, 109 ... gamma part, 301 ... selector, 30
2 ... LUT.

──────────────────────────────────────────────────続 き Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI H04N 1/46 H04N 1/46 Z (56) References JP-A-62-254187 (JP, A) JP-A-61-113097 ( JP, A) JP-A-62-49476 (JP, A) JP-A-62-185466 (JP, A) JP-A-63-167571 (JP, A) JP-A-61-240769 (JP, A) "ASCII ", Vol. 10, No. 11 November 1986, Askey Corporation, p. 140-141, Post Script section, “Introduction to Interpress”, Robert F. et al. Sproll, Brian K. Reid, April 1984, Fuji Xerox Co. Ltd, pp. 1-15, p. 155, Chapter 15, first paragraph, pp. 168-169, 15.5

Claims (4)

(57) [Claims] 1. An image processing method for an image forming apparatus for forming an image based on digital image information in a page description language, comprising: holding digital image information in a page description language input from an external device; A plurality of conversion processing conditions corresponding to the type are held in advance, and from among the plurality of stored conversion processing conditions, a conversion processing condition corresponding to the type of the image indicated by the held digital image information is used. An image processing method characterized by developing an output image on a bit plane while performing conversion processing on digital image information. 2. The digital image information includes graphic information represented by a bit image or vector information and text data information, and the graphic information and the text data information are held in separate memory areas. The image processing method according to claim 1, wherein: 3. The image forming apparatus according to claim 1, wherein the conversion process performs a density conversion according to a density conversion characteristic of the image forming apparatus so that the image forming apparatus can form an image. Image processing method. 4. An image processing method for an image forming apparatus for forming an image based on digital image information in a page description language, comprising control information in a bitmap format based on input digital image information in a page description language. Is held in a one-to-one correspondence with each pixel of the output image to be developed, and a plurality of conversion processing conditions corresponding to the type of image indicated by the digital image information are held in advance, and the control information in the bitmap format is An image processing method comprising: performing a conversion process on an image represented by the digital image information by using a conversion processing condition selected from the plurality of conversion processing conditions based on the image processing information.