JPH0512395A - Color image processor - Google Patents

Abstract

PURPOSE:To reduce deterioration in picture quality due to a compressing/ expanding process by storing document information partially in the form of a binary image, and limiting an image to be converted into binary data to specific character information. CONSTITUTION:The received document information in page description (PDL) form is not all converted into a many-valued image, but partially converted by a binary image generation part 3 into a binary image, which is stored in a binary image memory 4. Consequently, a PDL code analytic part 2 divides the specific information to be converted into binary data in the document according to predetermined division conditions. An image composition part 9 puts the binary-coded image and many-valued image together into one. The capacity of the memory for image information storage need not be increased. Further, the image to be converted into the binary image is limited to the specific information, e.g. black-specified character information or small-shape character information to reduce the deterioration in the picture quality which is caused by the compressing/expanding process before.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an image processing apparatus, and more particularly,
Document information including character images and other color image information is PDL
(Page description language) The present invention relates to a color image processing apparatus for inputting in the form of a code, converting it into a multi-valued color image, and outputting it.

[0002]

2. Description of the Related Art Conventionally, there is known a color image forming apparatus which inputs a PDL code containing color information, forms a multi-valued color image from the input PDL code, and outputs a full color image. This kind of color image forming apparatus is provided with a storage circuit capable of storing a multivalued color image for one page, and a multivalued color image formed from a PDL code is drawn and output there. However, this type of color image forming apparatus has a drawback in that the product cost becomes high because a large amount of memory circuits are required. Therefore, recently, a storage circuit capable of storing a multi-valued color image of about one-eighth page, a means for compressing a color image, a means for expanding a compressed color compressed image, and a color compression for one page Equipped with a storage device that can store images, PDL
There has been devised a device that forms an image from a code, compresses a color image and stores it in a color compressed image memory, and then decompresses and outputs the color compressed image in the color compressed image memory.

[0003]

However, in the above-mentioned conventional example, a full-color image can be output with a small storage device, but since the color image is compressed and then expanded, it is output.
There is a drawback that the image is deteriorated in details, especially in a small character portion.

Therefore, an object of the present invention is to provide a color image processing apparatus capable of mitigating the deterioration of image quality while making the most of the advantages of compression and expansion processing.

[0005]

In order to achieve such an object, the present invention inputs document information in which color image information is mixed in the form of a page description language code, converts it into a multi-valued image, and then compresses it. In a color image processing apparatus that performs decompression image processing to convert the document information into a color image, the input document information is converted into binary image information into first image information and multi-valued image information. A page description language code analysis unit that divides the second image information to be converted according to a predetermined division condition, and the divided first image information.
Binary image forming means for converting image information into binary image information, storage means for storing the converted binary image information, and binary image information in the storage means for converting into binary image information, The multi-valued image information is combined with the multi-valued image information obtained by performing the image processing on the second image information divided by the page description language code analysis means.

[0006]

According to the present invention, conventionally, all the document information converted into a multi-valued image is partially stored in the form of a binarized image, so that the capacity of the memory for storing the image information is significantly increased. There is nothing to do. Further, by limiting the image to be binarized to specific character information, for example, character information specifying black color or character information having a small shape, deterioration of image quality conventionally caused by compression and expansion processing. Can be blocked.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram of a first embodiment of the present invention, in which 1 is an input buffer and 2 is a PDL code analysis unit for analyzing the contents of a PDL code. 3 is a binary image forming unit, 4 is a binary image memory (storage means of the present invention),
Reference numeral 5 is a color image forming section. 6 is a color image compression unit,
Reference numeral 7 is a color compressed image memory, and 8 is a color image expansion unit. Reference numeral 9 is an image composition unit, and 10 is a printer engine.

The input buffer 1 is a buffer for temporarily storing a PDL code.

The information indicated by the PDL code includes font designation information for designating a character font, character information for designating a character to be printed, graphic information for designating the type and size of a graphic, and position information for designating a print position. , And color information for specifying the color. Input buffer 1 for PDL code
From the PDL code analysis unit 2.

A central processing unit (CPU) is used for the PDL code analysis unit 2, and print position information and color information are added to each print element such as characters and figures, and color information is added in accordance with the print position information. Arrange the order. After that, if the color designation by the color information can be determined to be black, P
The DL code is sent to the binary image forming unit 3, and if not, the PDL code is sent to the color image forming unit 5.

In this embodiment, the printer engine prints various colors by mixing yellow, magenta, cyan, and black inks having 256 levels of density from "0" to "255". Specifies the recording color by specifying the density amounts of the yellow, magenta, cyan, and black inks.

In the color information, the designation of black ink is "255" which is the maximum density value, and the designation of yellow, magenta and cyan inks are all the maximum density value "25".
If it is 5 ", it is determined that the color designation is black.

Further, when the user has designated to print with two colors of black and white, or when there is no color designation by the user, it is predetermined to print with black, and the color designation by the user is made. Even if there is not, the color designation is determined to be black.

The binary image forming section 3 forms a binary image of characters and figures from the PDL code and draws the image in the binary image memory. The binary image memory can store one page of binary image.

The color image forming section 5 forms a color image of characters and figures from the PDL code. The difference between a color image and a binary image is that for each dot, the color image has density information of cyan, magenta, yellow, and black, whereas the binary image has ON (OFF) and OFF (OFF). The point is that there is only binary information.

FIG. 2 shows an example of a dot pattern of a binary image, and each dot is composed of bits "1" or "0". The binary image can represent the shape of the image but cannot represent the color.

FIG. 3 is an example of a dot pattern of a color image. 12 is yellow, 13 is magenta, 14 is cyan,
Reference numeral 15 is a black dot image. These four dot patterns are overlapped to form one color image, and each dot is composed of “0” to “2” for each of yellow, magenta, cyan, and black.
It is expressed by density values up to 55 ".

The color image forming section 5 forms a color image of characters and figures from the PDL code, and the color image compression section 6
The image is compressed by and stored in the color compressed image memory 7.

The color image expansion unit 8 expands the color compressed image in the color compressed image memory 7.

The image synthesizing unit 9 synthesizes the binary image in the binary image memory 4 and the color image decompressed by the color image decompressing unit 8 and outputs it to the printer engine 10.

The printer engine 10 prints a full-color image by applying a specified amount of ink in the order of yellow, magenta, cyan, and black ink on paper.

FIG. 4 is a flow chart showing the operation contents of the PDL code analysis unit 2.

In the figure, it is determined in S16 whether or not the color designation is black, based on the color information. If it can be determined that it is black, S17
Then, the PDL code is sent to the binary image forming unit 3. If it cannot be determined that the color designation is black, the process proceeds to S18, and the PDL code is sent to the color image forming unit 5.

FIG. 5 is a flow chart showing the operation of the image synthesizing section 9.

In the figure, in S19, the color image decompression unit 8
First, input the yellow image and then the printer engine 10
Then, in step S20, the magenta image is input from the color image decompression unit 8 and sent to the printer engine 10. S21
Then, the cyan image is input from the color image expansion unit 8 and sent to the printer engine 10.

In S22, the black image input from the color image decompression unit 8 and the binary image in the binary image memory 4 are compared for each dot. When the bit value of the dot of the binary image is "1", the density value of the black image is multi-valued to "255" to be a combined value. When the bit value of the dot of the binary image is "0", an image signal having the density value indicated by the black image from the color image decompression unit 8 as a composite value is created, and the printer engine 10
Send to.

In this embodiment, the character part is formed as a binary image in the formation of a general color document image in which the character part is designated as black and a figure is drawn in various colors.
In addition, since the graphic portion in the color document image is formed, compressed, and expanded as a color image, and then combined with the binary image to be output, a multi-value color image with no image deterioration in the character portion is stored in a storage circuit device. Can be formed with.

(Second Embodiment) In the first embodiment, the PDL is used.
The code analysis unit 2 checks the color designation for each print element such as characters and figures, and if the color designation can be determined to be black, then PD
Send the L code to the binary image forming unit, otherwise P
The DL code was sent to the color image forming unit 3. However, image composition can also be performed in the following image processing order. The binary image forming unit 3 forms a binary image for all print elements, and if the color designation can be determined to be black, the formed image is drawn in the binary image memory 4. If not, the formed image and color information are stored in the color image forming unit 5.
Then, the color image forming unit 5 multi-values the image based on the color information to form a multi-valued color image. FIG. 6 shows a circuit configuration for performing image processing in such an order. In this embodiment, the binary image forming section 5 forms an image, and the color image forming section only colors the image. Therefore, a circuit can be constructed with fewer circuit components than in the first embodiment.

(Third Embodiment) The printer engine of the first embodiment is a printer engine having four types of inks of yellow, magenta, cyan and black.
A printer engine having three types of ink, magenta and cyan, may be used. In this case, in the synthesis of the binary image and the image of each ink color, the dot which is “1” in the binary image is set to multi-valued “255”, and black is yellow, magenta, cyan having the density of “255”. Printed with ink.

(Fourth Embodiment) Although the image is output to the printer in the first embodiment, the output target may be a display such as a CRT or a liquid crystal. In this case the color is red,
In the combination, it is composed of green and blue, and the dot that is "1" in the binary image is set to "0", and the black is "0".
It is composed of red, green, and blue of brightness.

(Fifth Embodiment) In the first embodiment, the condition for dividing and extracting as the image to be binarized is the image having the designated black color, but it may be another color. An example will be described in which the most designated number of colors among the designated colors of characters on one page is detected and the character image for which the color is designated is binarized.

In the case of this example, the division processing executed by the PDL code analysis unit 2 of FIG. 1 is as shown in FIG. That is, in S111, the character information is detected from the beginning of the received image information, and the number of characters in the color indicated by the color designation information of the character information is counted for each detection. Next, the color with the largest number of characters in the count result for each color is selected.
In S112, the color designation of each print element such as characters and figures in the received image information is checked, and if the color designation is the selected color, the PDL code is sent to the binary image forming unit 3 in S113. When the color designation is not the selected color, P in S14
The DL code is sent to the color image forming unit 5.

A flow chart showing the operation of the image synthesizing section 9 is shown in FIG.

For example, when yellow is the selected color, the image synthesizing unit 9 multi-values the binary image with the yellow density of the selected color when the yellow image is input from the color image decompressing unit 8 in S115. Next, the multi-valued image and the image input from the color image decompression unit 8 are combined and sent to the printer engine 10. To make a binary image multi-valued with the yellow density of the selected color, if each dot of the binary image has a dot of "1", it is converted into a predetermined yellow density, and if the dot is "0", the yellow density is converted. Is left at "0". Also, the above 2
To combine two pieces of image information, the density values of the corresponding dots of the two images are compared, and the larger density value is set as the density value of that dot.

In S16-18, the same image processing as described above is performed on the magenta image, the cyan image and the black image. This embodiment is suitable for forming a color document image in which a character portion is one color and a figure is drawn in various colors, and the character portion is formed as a binary image. Other graphic parts are formed as a color image, compressed, expanded, and then
Since the composite output is performed, it is possible to realize a multi-valued color image having no image deterioration in the character portion with a device having a small storage circuit.

(Sixth Embodiment) In the fifth embodiment, when an image obtained by converting a binary image into a multi-valued image and an image after decompression are combined, the density of these two images is compared for each dot to obtain a high density value. Image information is selected for output. For example, when a black character image is subjected to binarization, the output image looks like a black character overwritten on the color image.

Contrary to this, an example will be shown of a case where an output image in which a color image is overwritten on a black character image is to be obtained. FIG. 9 shows a processing procedure executed by the color image forming unit 5 in FIG. 1 for such processing.

The processing procedure executed by the image composition section 9 is shown in FIG.

The color image forming section 5 converts the image information divided by the PDL code analyzing section 2, that is, the image information in the PDL code form excluding the black characters into a binary image S17.
Then, first form. A black character image is obtained by inverting the binary image formed in S18, ANDing the binary image inverted in S19 with the image in the binary image memory 4, and drawing the AND result in the binary image memory 4. And the binary image of the overlapping portion of the other color image is erased. For reference, FIG. 11 shows the dot pattern 11 formed by the binary image forming unit 3 for the black character “◯”. Further, reference numeral 12 indicates a dot pattern of another color symbol “−” formed by the color image forming unit 5. Further, a reverse pattern of the dot pattern 12 and a dot pattern obtained as an AND result of the dot pattern 11 are indicated by reference numeral 13.

In S20, a multi-valued color image is formed from the PDL code.

In FIG. 10, the image synthesizing unit 9 inputs the yellow image from the color image expanding unit 8 and sends it to the printer engine in S21, and inputs the magenta image from the color image expanding unit 8 in S22 and sends it to the printer engine 10. , S
At 23, the cyan image is input from the color image decompression unit 8 and sent to the printer engine 10.

Subsequently, a black image is input from the color image decompression unit 8 and this black image and the binary image in the binary image memory 4 are compared dot by dot. When the value of the binary image is "1", the density value is "255", and when the value of the binary image is "0", an image having the density value of the black image is created, and the printer engine 10 Send to. In this embodiment, when a non-black figure overlaps a black character, the black portion overlapped by the figure is erased in the binary image memory 4, so the color of the figure is appropriately printed without discoloration. When the black character overlaps the graphic, the black character is printed as if it was drawn on the graphic by the above-described image synthesizing method, and the character image is clearly expressed.

In the formation of a general color document image in which the character part is designated as black and the figure is drawn in various colors, the character part is formed as a binary image and the figure part is formed as a color image. Since the image data is compressed and expanded, and then combined and output, a multi-valued color image without image deterioration in the character portion can be formed by a device having a small number of memory circuits, similarly to this embodiment.

(Seventh Embodiment) In the fifth embodiment, a character image of one black color is selected as an object of binarization, but a plurality of colors are selected for each color in descending order of the number of characters counted or for a predetermined color. The image information of 1 may be the object of binarization. In this case, a plurality of image memories may be provided, and the color of the image information stored in the binary stroke number memory may be selected.

Corresponding colors to each binary image memory,
For each print element, it is the same as in the fifth embodiment that the selected color is matched with the color designation of the received image information and the binary image is formed in the matched binary image memory.

Further, in the image composition, similarly to the composition of two images, when the number of images is three or more, the composition of two images is further combined. This makes it possible to form a color document without image deterioration in the character portion even when characters are printed in several colors.

(Eighth Embodiment) In the fifth embodiment, the type of an image which is a binary object is limited to a character, but not only a character but also a figure or the like is included in an object to be binarized, and each image is colored. Alternatively, the number of print elements may be obtained, and the PDL code analysis unit 2 may select one or several colors having the most print elements. Even in a color document that does not include characters, the optimum selected color can be formed as a binary image.

(Ninth Embodiment) A character image to be binarized may be a character having a large number of strokes or a character having a small shape. In this case, the character information to be binarized is stored in advance in the PDL code analysis unit 2 in a table form, and a table search is performed to determine whether or not the same character information as the received character information is included in this table. Determined by

[0050]

As described above, according to the present invention, conventionally, the document information which is all converted into the multi-valued image is partially stored in the form of the binarized image. Does not significantly increase the amount of memory used for storage. Further, by limiting the image to be binarized to specific character information, for example, character information specifying black color or character information having a small shape, deterioration of image quality conventionally caused by compression and expansion processing. Can be blocked.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of binary image information according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of multi-valued image information according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing an image division processing procedure and division conditions of the PDL code analysis unit 2 in FIG.

5 is a flowchart showing a processing procedure of an image synthesizing unit 9 in FIG.

FIG. 6 is a block diagram showing a circuit configuration of a second embodiment of the present invention.

FIG. 7 is a flowchart showing an image division processing procedure of the fifth embodiment of the present invention.

FIG. 8 is a flowchart showing an image synthesizing processing procedure according to the fifth embodiment of the present invention.

FIG. 9 is a flowchart showing an image processing procedure of the color image forming unit 5 according to the sixth embodiment of the present invention.

FIG. 10 is a flowchart showing an image synthesizing processing procedure according to the sixth embodiment of the present invention.

FIG. 11 is an explanatory diagram showing an example of binary image information according to the sixth embodiment of the present invention.

[Explanation of symbols]

 1 Input Buffer 2 PDL Code Analysis Unit 3 Binary Image Forming Unit 4 Binary Image Memory 5 Color Image Forming Unit 6 Color Image Compressing Unit 7 Color Compressed Image Memory 8 Color Image Decompressing Unit 9 Image Compositing Unit 10 Printer Engine

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Claims (1)

Claim: What is claimed is: 1. Document information in which color image information is mixed is input in the form of a page description language code, converted into a multi-valued image, and then image processing of compression and decompression is performed to obtain the document information. In a color image processing apparatus for converting a color image into a color image, the input document information is predetermined as first image information to be converted into binary image information and second image information to be converted into multivalued image information. A page description language code analyzing unit for dividing the divided first image information according to the dividing condition, a binary image forming unit for converting the divided first image information into binary image information, and a storage for storing the converted binary image information. Means for converting the binary image information in the storage means into multivalued image information, and performing the image processing on the multivalued image information and the second image information divided by the page description language code analysis means. Color image processing apparatus, characterized in that it comprises a synthesizing means for synthesizing the multivalued image data.