JP2002252773A - Color image processing method and device, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm a character part and a graphic part colored differently from a color of the surrounding in the case of monochromatically outputting a color image on an output device. SOLUTION: The character part in the color image is identified (S2), the character part whose hue differs from that of the surrounding is extracted through the retrieval of the hue (S3, S4), gray conversion is applied to the character part (S5), after emphasis processing (S6) is applied, the resulting data are synthesized with other gray data (S8), and obtained data D7 are subjected to pseudo gradation processing for later monochromatic outputs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process performed when a color image having a halftone is output in monochrome to an output device.
More specifically, the present invention relates to a processing method and an apparatus for enabling a character or graphic portion of the color image to be confirmed even when output in black and white, and a recording medium on which a program for that is recorded.

[0002]

2. Description of the Related Art In recent years, with the development of image processing technology and the reduction in prices of data storage devices such as memories and hard disks, most digital images have become color data. Color printers that support color printing are also becoming popular, but cost savings and color printing are not necessary.
Because you want to print black and white as a special effect,
In many cases, color data is output in monochrome, in other words, output to a monochrome printer, or output to a color printer having a monochrome mode to perform monochrome printing.
When color image data is output in monochrome, it is necessary to convert data representing a color image from a computer or the like into density information data, that is, perform gray conversion, in order to improve the finish of printout.

[0003] Gray conversion is performed, for example, by using the R,
The conversion can be performed by converting the G and B values into the gray value of the pixel.

Gray value = 0.3R + 0.6G + 0.1B (1) The gray value represents the density information of a monochrome image.

[0005]

However, as can be seen from the above equation (1), the gray value is determined by the combination of the R, G, and B values. Gray values can be equal. Therefore, if the objects having different colors in the color image before the gray conversion have similar gray values after the gray conversion, these objects have the same density in a printed matter obtained by monochrome output, and cannot be distinguished. Sometimes. Also, when creating a color image, for example, objects such as characters and figures are distinguished or emphasized so that they can be seen at a glance, and these objects are colored. ,
In some cases, these objects are printed in the same shade as the surroundings, and a portion that is originally intended to be conspicuous as a feature may not even be discriminated.

This problem occurs not only in printers but also in output devices such as copiers for copying color images (including color copiers capable of monochrome copying).

In a system for making and printing a color image in monochrome, a color portion is represented by a density difference using a pseudo gradation process called a halftone process. However, in the gradation processing in the halftone processing, aside from the photographic part that requires a wide range of reproduction from low density to high density, characters, graphics, etc., especially thin characters, graphics, etc.
Depending on the pattern size of the halftone dots, it is often impossible to determine them visually.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. In a system for making and printing a monochrome plate, when a color image is output in monochrome to an output device, characters and figures to be emphasized in the color image are surely output. It is an object of the present invention to provide a color image processing method and apparatus capable of making a determination and a recording medium on which a program for the method is recorded.

[0009]

According to the color image processing method of the present invention, when a color image including a character portion and / or a graphic portion is monochrome-outputted to an output device to obtain a printed matter, the color image is subjected to surroundings. In this case, a character portion and / or a graphic portion having a different hue from that of the above are detected, and the detected character portion and / or graphic portion is subjected to an emphasis process.

[0010] Here, the "output device" means a printer, a copier, or the like that receives the input color image, duplicates the color image on a print medium such as paper or film, and obtains a printed matter. The “printer” is not limited to a printer generally described by the term “printer” such as a laser printer or an ink jet printer, and can be connected to a computer or the like via a printer terminal or a network terminal. All that can obtain an image copy according to the instruction are included. Needless to say, a stencil printing machine that receives image data from a computer and performs stencil making and printing is also included in the “printer” here.

The term "monochrome output" of a color image means that the color image obtained by an image input device such as a computer or a scanner is output to a monochrome output device (monochrome printer, monochrome copier, etc.) This means outputting to a color output device capable of printing (including copying) and performing monochrome printing (copying).

The phrase "different in hue" means that the color is different. In other words, the detected character portion and / or graphic portion and its surroundings are green and red (character portion and graphic portion, respectively). (A green color and a red background), as well as a color that can be visually recognized as a different color on a color image, and broadly includes a color that is desired to be distinguished on a monochrome print.

The "enhancing process" is to enhance the detected character portion and / or graphic portion (hereinafter, detected portion) and its periphery in a printed matter obtained by monochrome output of the color image. Any process that can be performed may be used. For example, in order to simplify the processing and clearly convey the image of the entirety of the detected portion, the difference between the detected portion and the surrounding gray value is set to a predetermined value or more, that is, a gray value conversion process is performed. , The detected portion can be emphasized. In the gray value conversion process, the gray value of only the detected portion or only the periphery of the detected portion may be converted, or the gray value of both the detected portion and its surroundings may be converted. Of course, the value may be converted.

In addition, from the viewpoint that the detected portion and the density (gray value) around the detected portion are not changed and the detected portion can be determined, the color image processing method of the present invention The emphasizing process may perform an edge emphasizing process on the detected portion.

A color image processing apparatus according to the present invention is a color image processing apparatus for outputting a color image including a character portion and / or a graphic portion to an output device in a monochrome manner to obtain a printed matter. Detecting means for detecting a character part and / or a graphic part having a hue different from the surroundings, and emphasizing processing means for performing an emphasis process on the character part and / or the graphic part detected by the detecting means. It is characterized by the following.

It is preferable that the emphasis means makes a difference between the detected character part and / or graphic part (hereinafter referred to as a detected part) and its surrounding gray value equal to or more than a predetermined value.

From the viewpoint that the detected portion can be confirmed on the printed matter without changing the detected portion and the density (gray value) around the detected portion, the emphasizing processing means in the present invention may be modified as follows. The edge enhancement processing may be performed on the detected part.

The color image processing apparatus of the present invention may be built into an image output device, such as a computer, a scanner, or another image input device and an independent interface located between the output device. When the output device is a printer, it is preferable that the detecting means and the emphasis processing means of the present invention are constituted by a printer driver or a part of the printer driver.

The recording medium of the present invention is a recording medium in which a program for performing color image processing when a color image including a character portion and / or a graphic portion is monochrome-outputted to an output device to obtain a printed matter is recorded. , Said program
A step of detecting a character part and / or a graphic part having a different hue from the surroundings of the color image and performing an emphasis process on the detected character part and / or the graphic part. It is.

Here, the "recording medium" may be any recording medium on which a program for performing the color image processing is recorded. This includes not only a floppy (registered trademark) disk and a CD-ROM in which the printer driver is recorded, but also a ROM, a chip, and the like which record the program and are mounted on the output device.

[0021]

According to the color image processing method and apparatus of the present invention, when a color image including a character portion and / or a graphic portion is monochrome-outputted to an output device to obtain a print, the color image is Character portions having different hues, in other words, character portions and / or graphic portions emphasized by coloring are detected, and the detected portion is subjected to emphasis processing. Characters and graphics having different colors can be surely emphasized even in a monochrome output printed matter.

In addition, for a detected character or graphic, processing for making the difference between the character or graphic itself and its surrounding gray value equal to or more than a predetermined value, that is, a detected part or its surroundings, or a detected part If the detected characters and graphics are changed by performing the gray value change processing for both the surroundings and the surroundings, the processing can be simplified, and the images of the detected characters and graphics can be clearly conveyed.

As the same emphasis processing, if the extracted characters and figures are subjected to edge emphasizing processing without changing the gray value, the characters and figures are emphasized, and the characters, figures and the shaded image around them are emphasized. Can be expressed in printed matter as it is.

When the output device is a printer, if the above-described detection and emphasis processing is performed by the printer driver, the printer driver and the printer have a one-to-one relationship, so that it is easy to make detailed settings and the like. There is an advantage.

A recording medium on which the program of the present invention is recorded stores a program for performing the above-described image processing, and is installed in a computer or mounted on an independent color image processing apparatus or output apparatus. Each of the computer, the color image processing device, and the output device can be the color image processing device of the present invention.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart showing a color image processing process by a printer driver according to an embodiment of the present invention.

As shown, the printer driver according to the embodiment of the present invention receives color image data D1 of an image output device such as a computer (S1), and uses the character identification function of the printer driver to generate image data D1. A character portion in the middle is identified (S2), a hue scan is performed, a character portion having a different hue from its surroundings is detected in these character portions, and these character portions are extracted and data D2 is extracted. Obtain (S4).
After performing gray conversion on the data D2, (S
5) Perform emphasis processing (details will be described later),
Data D5 to be embedded in data D6 described later is obtained (S6).

On the other hand, in step S4, gray conversion is performed on the remaining image data D3 from which the data D2 is extracted from the color image D1 (S7), and the data D2 is extracted.
Get 6. The gray data D6 is combined with the data D5 obtained by subjecting the extracted character data D2 to gray conversion and emphasis processing by the integration and incorporation process to become gray data D7 of the color image data D1 (S8). The gray data D7 is subjected to error diffusion processing for monochrome output, pseudo-tone processing such as halftone processing and simple binarization processing in step S9, and output to the printer (S10).

Next, the operation of the printer driver shown in FIG. 1 will be described in more detail by taking the color image data shown in FIG. 2 as an example.

The color image data of the example shown in FIG. 2 is composed of a green background 1 and a character "A" written in red on the background 1. Background 1
Are not clear because the gray values are close to each other (in FIG. 2, the character A is shown so as to be distinguished for the sake of explanation). Thus, the character "A" is first identified by the printer driver shown in FIG. 1 by the character identification function of the printer driver (S1). The printer driver then scans the hue of the color image of FIG. 2 (S3), and extracts the character "A" because the hue of the character "A" is different from the hue of the background 1 (S4). The extracted character "A" and the background 1 from which the character "A" is extracted are subjected to gray conversion processing (S5, S6).

Here, the details of the emphasis processing (S6) performed on the gray-converted character "A" will be described. As the emphasis processing, the letter “A” is added to the printed matter obtained by monochrome printing.
May be any processing as long as the processing is emphasized and can be clearly distinguished. Specifically, the following method can be used.

One is a method in which the difference between the gray value of the character "A" and the gray value of the background is equal to or larger than a predetermined value (for example, 20). As shown in FIG. 3A, the character “A” may be blackened (the gray value is maximized).
As shown in (b), the character “A” may be deleted (the gray value is set to 0). Of course, besides making the character “A” black and white, the gray value of either or both of the character “A” and the background 1 may be adjusted so that the character “A” and the background 1 can be clearly seen in the printed matter. Good.

FIGS. 3C and 3D respectively show the character "A".
3 shows an image of a printed material obtained by deleting and emphasizing (blackening) the edges. Regarding the detection of the edge of the character “A”, for example, first, for the gray data D4 of the character “A” obtained by performing the gray conversion in step S5 described above,
As shown in FIG. 4A, the search is performed from the top to the bottom, and points (shaded portions in the drawing) at which the density has extremely changed are sequentially found. Then, as shown in FIG. 4B, FIG. 4C, and FIG. 4D, a point at which the density extremely changes from bottom to top, from left to right, and from right to left is found. FIG. 4E shows the edge 2 of the character “A” detected by the above search.
Is shown. The printed matter obtained by deleting and enhancing the edge 2 shown in FIG. 4E is shown in FIG.
The image is as shown in FIG.

With any of the above-mentioned enhancement methods,
In the monochrome printed matter of the color image data shown in FIG. 2, the background 1 and the character "A" can be clearly distinguished. The method of changing the gray value does not require the search for the edge of the character part, so the processing is simple, and the method of emphasizing (including deleting) the gray value for both the character “A” and the background 1 Since we don't make any changes to
Since there is a merit that the original image of the character "A" and the original image of the background 1 can be expressed as they are, they may be selected and applied according to preference or the like.

As described above, according to the printer driver of the embodiment, when a color image is output to a monochrome printer (or a color printer in a monochrome mode) to obtain a print, Since the character portion having a different hue from the surroundings, in other words, the character portion emphasized by coloring is detected, and the detected portion is subjected to the emphasis processing, the color different from the surroundings in the original color image is detected. Can be reliably determined and emphasized even in a monochrome printed matter.

In the above-described printer driver, only the processing for characters has been described as an example, but the same applies to a graphic part.

In the above-described embodiment, a printer driver installed in a computer is used as the color image processing apparatus. However, a program having the processing procedure of FIG. 1 is implemented as a part of a processing program of a printer serving as an output apparatus. Then, the printer itself can also serve as the color image processing device of the present invention.

Further, the color image processing apparatus of the present invention may be constituted as an external interface independent of a computer and a printer.

In the above embodiment, the output device is a printer, and the color image data is created by image software. However, the color image processing device of the present invention is not limited to the above configuration. But not letters,
If a figure or the like can be identified, the present invention can be applied to a case where a scanner is used for acquiring a color image or a copying machine is used as an output device.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a color image processing process performed by a printer driver according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of color image data.

3 is an image diagram of a printed matter obtained by emphasizing a character portion of the image data shown in FIG. 2;

FIG. 4 is a diagram for explaining an edge search of a character portion;

[Explanation of symbols]

 1 Background 2 Edge

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) H04N 1/40 H04N 1/40 F 1/409 101D F-term (reference) 2C062 AA24 2C087 AA11 AA15 AA16 BA05 BD07 BD31 CB13 5B057 AA11 BA02 CA01 CA08 CA12 CA16 CB02 CB07 CB12 CB16 CC01 CE13 CE17 CH08 5C077 LL19 MP08 NN02 PP03 PP27 PP28 PP32 PP37 PQ12 SS02 TT02 5C079 HA11 HB01 LA02 LA06 LA15 NA06 PA02 PA03

Claims (8)

[Claims] When a printed matter is obtained by outputting a color image including a character portion and / or a graphic portion to an output device in monochrome,
Color image processing, wherein a character portion and / or a graphic portion having a different hue from the surroundings of the color image are detected, and the detected character portion and / or graphic portion are subjected to enhancement processing. Method. 2. The method according to claim 1, wherein the emphasizing process is a gray value conversion process for making a difference between the detected character portion and / or graphic portion and a surrounding gray value a predetermined value or more. Color image processing method. 3. The color image processing method according to claim 1, wherein said emphasizing process is an edge emphasizing process for said detected character part and / or graphic part. 4. A color image processing apparatus for obtaining a printed matter by outputting a color image including a character portion and / or a graphic portion to an output device in a monochrome manner, wherein the color image has a hue as compared with the surroundings. A color image comprising: detecting means for detecting different character parts and / or graphic parts; and emphasizing processing means for performing emphasis processing on the character parts and / or graphic parts detected by the detecting means. Processing equipment. 5. A color image according to claim 4, wherein said emphasizing means makes a difference between the detected character portion and / or graphic portion and a gray value around the detected character portion and / or graphic portion a predetermined value or more. Processing equipment. 6. A color image processing apparatus according to claim 4, wherein said emphasis processing means performs an edge emphasis process on the detected character portion and / or graphic portion. 7. A color printer according to claim 4, wherein said output device is a printer, and said detecting means and emphasis processing means are a printer driver or a part of a printer driver. Image processing device. 8. A recording medium storing a program for performing color image processing when a color image including a character portion and / or a graphic portion is monochrome-outputted to an output device to obtain a printed matter, wherein the program is: The method further includes a step of detecting a character portion and / or a graphic portion having a different hue from the surroundings of the color image and performing an emphasis process on the detected character portion and / or graphic portion. A recording medium characterized by the above-mentioned.