JPH05207305A - Picture processor - Google Patents

Abstract

PURPOSE:To provide a picture processor by which a color replacement can be attained without deteriorating a picture quality. CONSTITUTION:Picture data read through a picture data I/F 5 are stored in image memories 6-8, inputted to LUT 9-11, and the color replacement is operated based on conversion data stored in the LUT 9-11. A CPU 1 allows a threshold value setting part 14 and a color setting part 15 to set a threshold and a color for operating the color replacement, and allows an LUT setting part 16 to calculate the conversion data to be stored in the LUT 9-11 based on the set threshold value and color. Then, the obtained conversion data are stored through a CPU bus 4 in the LUT 9-11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, for example, an image processing apparatus for replacing color information of input image data with an arbitrary color.

[0002]

2. Description of the Related Art For example, when a two-color image printed with black ink on a white background is read by a scanner and input to a computer, and then the two colors of the original image are replaced with different colors, the brightness is conventionally changed. There is a method in which a certain threshold value is set, and the color information of the image data having the luminance exceeding the threshold value is replaced with the first color, and the color information of the image data having the luminance less than the threshold value is replaced with the second color.

FIG. 8 is a diagram showing an example in which the image data of the image contour portion is divided into two colors by the above conventional method. The horizontal axis is the scan position, the vertical axis is, for example, the brightness before the replacement and the brightness after the replacement. For example, the upper end is blue and the lower end is green. Reference numeral 801 represents a change in image data before color replacement, and 802 represents a change in image data after color replacement.

[0004]

However, the above conventional example has the following problems. That is, no matter what the threshold value is set to, a sharp color change occurs in the image contour portion, so that the image contour portion after color replacement has jagged edges, which deteriorates the image quality.

The present invention has been made in order to solve the above problems, and performs color replacement of a two-color image read by a scanner or the like without causing a jagged edge in the contour portion and degrading the image quality. It is an object of the present invention to provide an image processing device capable of performing the above.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and has the following structure as one means for solving the above problems. That is, a storage unit that stores the input image data, a color setting unit that sets the first color and the second color, a threshold setting unit that sets the first threshold value and the second threshold value, The color information of the image data stored in the storage means is set to the first color and the second color set by the color setting means based on the first threshold and the second threshold set by the threshold setting means. The image processing apparatus includes a color and a replacement unit that replaces the first color and the second color with a mixed color.

[0007]

With the above arrangement, it is possible to provide an image processing apparatus capable of performing color replacement without degrading image quality.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of an image processing apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a control processor unit (hereinafter referred to as "CPU"), which controls the main control of this embodiment.

Reference numeral 2 is a CPU memory, such as RAM or RO.
The color replacement program of the present embodiment and parameters necessary for the color replacement processing are stored. In addition,
The CPU 1 executes processing according to a program stored in the CPU memory 2. A CPU-interface (hereinafter referred to as "I / F") 3 is connected to a command input device such as a keyboard and a mouse (both not shown).

A CPU bus 4 is composed of three buses, an address bus, a data bus and a control bus. An image data I / F 5 is connected to an image input device such as a scanner and an image output device such as a printer, and outputs image data obtained by reading an original image and image data after color replacement. ..

Image memories 6 to 8 have a data width of, for example, 8 bits / pixel. The image memory R6 stores the red component of the image data, the image memory G7 stores the green component of the image data, and the image memory B8 stores the image data. Remember the blue component of. 9 to 11 are rutup table (hereinafter referred to as "L
UT ”), which is composed of, for example, a high-speed RAM,
The UTs 9 to 11 are gradation conversion tables having a storage capacity of 256 bytes, for example, and can be rewritten by the CPU 1.

Address terminals Adr of each LUT 9-11
Are connected to the output terminals Out of the image memories 6 to 8, and the output terminals Out of the LUTs 9 to 11 are connected to the video bus 12. For example, the 8-bit image data supplied from the image memories 6 to 8 are stored in the LUTs 9 to 9.
It is converted by the data stored in 11 and output to the video bus 12. Further, each LUT 9 to 11 has C
The PU bus 4 is connected, and the CPU 1 can always read and write the data stored in the LUTs 9 to 11 via the CPU bus 4.

A video controller 13 receives, for example, a total of 24 bits of image data from the LUTs 9 to 11 via the video bus 12, and generates and outputs a video signal from the image data. The video signal output by the video controller 13 is input to, for example, a CRT (not shown), and is used for monitoring images before and after color replacement, designating a color after replacement, and the like.

Reference numeral 14 denotes a threshold value setting unit for setting two upper and lower threshold values, which are the CPU bus 4 and the video bus 1.
Connected to 2. A color setting unit 15 is for setting the two colors after replacement, and is connected to the CPU bus 4 and the video bus 12. Reference numeral 16 is an LUT setting unit, which is an LU
It is for calculating conversion data to be stored in T9 to 11, and is connected to the CPU bus 4.

Reference numeral 17 denotes a memory replacement unit, which is an image memory 6
8 to 8 are for replacing the image data stored therein with the image data passed through the LUTs 9 to 11, and are connected to the CPU bus 4. 18 is an image memory controller,
It is for controlling the image memories 6 to 8 and the LUTs 9 to 11 in synchronization with the processing of the LUT setting unit 16 and the memory replacing unit 17, and is connected to the CPU bus 4.

In the following description, the image data at the address (x, y) is represented by A (x, y). However, when the brightness data Ai (x, y) of each color of RGB is represented, AR (x, y),
It is noted as AG (x, y) and AB (x, y). Furthermore, the brightness data Ai (x,
If the data width of y) is 8 bits, for example, the brightness of each color is represented by 256 gradations from minimum brightness 0 to maximum brightness 255.

FIG. 2 is a flow chart showing an example of the color replacement process of this embodiment. In FIG. 2, the image data obtained by reading the original image of the two-color image with, for example, a scanning device is stored in the image memories 6 to 8 via the image data I / F 5 and the CPU bus 4 by the CPU 1 in step S1. Remember. At this time, the LUTs 9 to 11 are set to the standard conversion characteristics having the same input and output as shown in FIG. 3, and the image data stored in the image memories 6 to 8 are
It can be monitored by a CRT or the like via the video bus 12 and the video controller 13.

Subsequently, in step S2, the CPU 1 operates the color setting unit 15 to set what color the bright part of the image data before replacement is to be replaced with. Similarly, in step S3, the color to replace the dark part of the image data before replacement is set. Specifically, from the color setting unit 15 to the video bus 12
And on the CRT etc. via the video controller 13,
As shown in FIG. 4, a color palette 401 and a message 402 “Please select a color for the light area” or “Select a color for the dark area” are displayed. An arbitrary color is selected from the color pallets by using a mouse connected to the. It should be noted that instead of selecting from the color palette, the CPU-
From the keyboard connected to the I / F3, select "255,0,
You can also specify a color by entering color data such as "0" or "100,200,100".

Subsequently, in step S4, the CPU 1 operates the threshold value setting section 14 to input two upper and lower threshold values. Specifically, a gradation bar 501 and an “OK” button 50, an example of which is shown in FIG. 5, are displayed on the CRT or the like from the threshold setting unit 14 via the video bus 12 and the video controller 13.
2 is displayed, and the operator of this embodiment uses the CPU-I /
By using a mouse or the like connected to F3 to move the triangular marks 503 and 504 shown in FIG. 5 to the left or right, the lower and upper threshold values are changed. Instead of changing the threshold value using the gradation bar, change the threshold value by entering a character string such as "92" or "321" from a keyboard connected to the CPU-I / F3. You can also

Then, in step S5, the CPU 1 sets the LU
The T setting unit 16 is operated to calculate each conversion data of the LUTs 9 to 11 based on the set two colors and the changed two upper and lower thresholds, and the conversion data obtained by the calculation is stored in the CPU bus 4 Write to LUTs 9-11 via.
Therefore, the LUTs 9 to 11 are set to the conversion characteristics based on the set two colors and the changed upper and lower two threshold values,
The images after the color replacement by the current threshold value are sequentially displayed on the CRT or the like via the video controller 13, and the operator of this embodiment can immediately confirm the images after the color replacement corresponding to the threshold value.

Subsequently, in step S6, the CPU 1 determines whether the "OK" button 502, an example of which is shown in FIG. 5, is "clicked" by a mouse or the like, and N
If O, the process returns to step S4, and if YES, the process proceeds to step S7. By inputting a specific code, for example, from a keyboard connected to the CPU-I / F3, the same operation as clicking the "OK" button can be performed.

Then, in step S7, the CPU 1 operates the memory replacement unit 17 to transfer the image data stored in the image memories 6 to 8 to the LUT 9 via the CPU bus 4.
It is replaced with the output image data of 11 to 11. Finally, in step S8, the CPU 1 initializes the LUTs 9 to 11 to the standard conversion characteristics having the same input and output, an example of which is shown in FIG.

Next, the effect of setting two upper and lower threshold values will be described. FIG. 6 is a diagram showing an example of changes in the image data of the image outline portion read by scanning, etc., where the horizontal axis is the scan position and the vertical axis is the brightness, for example. When the image data read by scanning or the like as shown in FIG. 6 is divided into two colors, for example, the threshold value Sh1 shown in FIG. 6 is set and the threshold value Sh1 is set.
It is a general method to set the first color for the luminance portion exceeding the threshold and the second color for the luminance portion below the threshold value Sh1. In this embodiment, two threshold values Sh having different values shown in FIG. 6 are used.
By setting 2 and Sh3, it is possible to prevent the occurrence of jagged edges in the image contour portion after color replacement, and to perform color replacement without image quality deterioration.

FIG. 7 is a diagram showing an example in which the image data of the image contour portion is divided into two colors according to the present embodiment. The horizontal axis represents the scan position, the vertical axis represents the brightness before replacement, and the brightness after replacement. For example, the upper end is blue, the lower end is green, and the middle is a mixture of blue and green. Reference numeral 701 represents a change in image data before color replacement, and 702 represents a change in image data after color replacement. In this embodiment, as shown in FIG. 7, the image data before replacement is 3
It is divided into two areas. That is, a portion that exceeds the threshold Sh2 (hereinafter referred to as "first region"), a portion that is equal to or less than the threshold Sh2 (hereinafter referred to as "second region"), and a portion that is equal to or less than the threshold Sh3 (hereinafter referred to as "first region"). 3 area ”).

Even with an original image having sharp edges, the image contour portion shows a smooth change in image data as shown in FIG. 7 due to sampling by scanner or the like.
In other words, since anti-aliasing is performed by sampling by scanning, etc., the first area is set to the first color specified in step S2, and the third area is set to step S2.
The second area is replaced with the second color specified in 3, and the second area is replaced with a mixed color of the first color and the second color corresponding to, for example, the luminance of the image data before the replacement. That is, as shown in FIG.
The first area is blue, the third area is green, and the second area is
The higher the brightness, the closer the color is to blue, and the lower the brightness, the color closer to green.

Assuming that the color Ci of the second area is C1, the second color is C2, and the brightness of an arbitrary point of the image data 801 before replacement shown in FIG. It is expressed by the formula. Ci = C1 (Bi-Sh3) / (Sh2-Sh3) + C2 (Sh2-Bi) / (Sh2-Sh3) As described above, according to the present embodiment, two threshold values are set and scanning is performed. Image data obtained by scanning
For example, the luminance is divided into three areas, the first area having high luminance is used as the first color, and the third area having low luminance is used as the second area.
The second area having the intermediate brightness is replaced with the mixed color of the first color and the second color corresponding to the brightness, so that the jagged edges of the image outline after the color replacement occur. It is possible to perform color replacement processing that prevents image deterioration and does not deteriorate image quality.

Further, according to the operator of this embodiment,
The two colors and two threshold values after replacement can be set arbitrarily. Especially, the threshold value can be set while monitoring the image after color replacement, so that the image contour portion after color replacement is sharp and has no jagged edges. It can be an optimum threshold. Further, in step S1 described above, the original images of two colors can be read as image data for one monochrome screen by using the monochrome filter, or by using the RGB color filter, the image memory 6 to 8
Color image as a color image, and then weighted and added by human visibility characteristics (R: G: B = 3: 6: 1) to obtain substantially the same result as image data for one monochrome screen. You can

Further, the method of interactively determining the threshold value using the mouse or the like has been described, but the threshold value may be given in advance as a parameter of the processing command. In the case of original images under the same conditions, the upper and lower two threshold values do not differ depending on the original image. Therefore, if the threshold value is determined for one image, it will be easier by giving the threshold value as a command parameter. It can be processed at high speed.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can also be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0030]

As described above, according to the present invention, it is possible to provide an image processing apparatus capable of performing color replacement without degrading image quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a flow chart showing an example of color replacement processing of the present embodiment.

FIG. 3 is a diagram showing an example of standard conversion characteristics of the LUT of the present embodiment.

FIG. 4 is a diagram showing an example of a display screen when a replacement color is designated in the present embodiment.

FIG. 5 is a diagram showing an example of a display screen when setting a threshold value in the present embodiment.

FIG. 6 is a diagram showing a change example of image data of an image contour portion read by a general scanner or the like.

FIG. 7 is a diagram showing an example of color replacement according to the present embodiment.

FIG. 8 is a diagram showing an example of color replacement by a conventional method.

[Explanation of symbols]

 1 CPU 2 CPU memory 3 CPU-I / F 4 CPU bus 5 Image data I / F 6 to 8 Image memory 9 to 11 LUT 12 Video bus 13 Video controller 14 Threshold setting unit 15 Color setting unit 16 LUT setting unit 17 Memory replacement Part 18 Image memory controller

Claims (2)

[Claims] 1. A storage unit for storing input image data, a color setting unit for setting a first color and a second color, and a threshold setting for setting a first threshold value and a second threshold value. Means and a first color set by the color setting means based on the first threshold value and the second threshold value set by the threshold value setting means, the color information of the image data stored in the storage means. An image processing apparatus comprising: a second color and a replacement unit that replaces the first color with a mixed color of the second color. 2. Storage means for storing input image data, color setting means for setting a first color and a second color, and threshold setting for setting a first threshold value and a second threshold value. Means and a first color set by the color setting means based on the first threshold value and the second threshold value set by the threshold value setting means, the color information of the image data stored in the storage means. A replacement unit that replaces the second color and the mixed color of the first color and the second color, wherein the replacement unit replaces the image data, the first threshold, and the second threshold with each other. The color information of the image data larger than the first threshold value is replaced with the first color, and the color information of the image data smaller than the second threshold value is compared with the second color information.
Of the second threshold, and is smaller than the first threshold value and smaller than the second threshold value.
The image processing apparatus is characterized in that the color information of the image data larger than the threshold value is replaced with a color mixture of the first color and the second color corresponding to the image data.