JPH0659105B2 - Color correction method in video plate making apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image correction method for correcting a video signal into a high-quality color image that can be used for plate making of color printing.

[Disadvantages of conventional technology]

Color printed matter has been used in various fields in recent years, and with it,
Opportunities for plate-making printing have been increasing using television (hereinafter referred to as TV) images that are abundantly provided as color image information.

A technique related to this is disclosed in, for example, JP-A-57-104935, JP-A-57-108857, or JP-A-59-78.
The one disclosed in Japanese Patent No. 350 is known.

However, the TV image obtained by the TV receiver often includes color cast, and the quality is low as it is for use as an original image for printing.

In addition, the color TV that is usually provided regardless of whether the image is received or directly shot by a video camera.
The image is based on the color signal system of the NTSC system (some video cameras also use R, G, B output). This color TV image is a color that seems to be based on that color signal system. Fogging development occurs around the contour of a person or the like, and deteriorates the image quality.

This also occurs in daily TV broadcasting, but since ordinary TV usually sees moving images, even if there is some color cast, it does not bother me, but when printing TV images, Since one scene is fixed and duplicated as a still image, even if there is a slight color shift, it stands out.

[Object of the Invention]

The present invention provides a color correction method for correcting a color video image including a color cast into a higher quality image by using an image correction device.

[Structure of Invention]

The present invention for achieving the above object is based on a video signal composed of red, green, and blue three-color image signals, which is subjected to highlight / shadow setup, color correction, and gradation correction, and is based on this video signal. During video plate making by scanning and recording a color separation plate for printing, the image based on the video signal is displayed on the monitor, the color cast candidate area in the display image on the monitor is partially specified, and the image in the specified area is specified. Depending on the size of the density difference between adjacent pixels, the outline part of the pattern is extracted and the color cast of the outline part is detected, and the color cast of the detected part is used as the color or color of the pattern in the display image. A method for color correction in a video plate making apparatus, characterized in that the replacement is performed by an output signal from a signal generator.

〔Example〕

FIG. 1 is a block diagram showing an example of an image correction apparatus for carrying out the present invention.

Although the following description is for an NTSC color TV image signal, any color TV signal may be originally used as long as it is an image signal converted into R, G, B. Modified T
As the V image signal, an image signal obtained from the TV receiver (only the tuner may be used) (1) or the TV camera (2),
Those recorded on a VTR (video tape recorder) (3), other magneto-optical disks, video disks, etc. can be mainly used.

From the TV images recorded on the VTR (3), a desired one screen, for example, one screen of one still image or one frame (two fields) of a TV image (one screen of a still image or a moving image Select (as a still image),
NTSC decoder (5) in synchronization with the timing generator (4)
To enter.

The NTSC decoder (5) converts the color image signal (g ₁ ) represented by the NTSC color signal system into red (R),
It is converted into an RGB color image signal (g ₂ ) represented by three color image signals (R), (G) and (B) of green (G) and blue (B). It should be noted that it is not necessary to use the NTSC decoder (5) for the original RGB signal.

The RGB color image signal (g ₂ ) is converted into a digital image signal (d ₁ ) for each color separation signal (R), (G), (B) by the A / D (analog / digital) converter (6). It is converted and sent to the first image memory (8) via the S / P (serial / parallel) converter (7).

Image signal (d ₂ ) read from the first image memory (8)
Is sent to one of the data inputs of the data selector (10) via the P / S (parallel / serial) converter (9), and
A microprocessor so that the CPU can obtain data at an arbitrary address of the first image memory (8) directly by an instruction of the CPU (central processing unit) without passing through the P / S converter (9). Input to the input port (12a) of the input / output interface (12) of the CPU (11).

The other data input of the data selector (10) is connected to the signal generator.
By (13), color data (d ₃ ) is input in order to display the correction data described below in pseudo color or to display the cursor.

The image signal (d ₄ ) output from the data selector (10) is P /
It is input to the second image memory (15) via the S converter (14).

The image signal (d ₅ ) read from the second image memory (15) is
Through the P / S converter (16), as described above, the CPU (11) sends data to an arbitrary address in the second image memory (15) to the input port (12a) so that the data is sent to the input port (12a). D / A
The image signal (g ₃ ) which is input to the (digital / analog) converter (17) and converted into analog there is a CRT controller.
Input to (18) and display on CRT monitor (18a).

To the other data input of the data selector (10), the CPU (11)
The image signal (d ₆ ) processed by the CPU (11) is input from the output port (12b) of the.

The image signal (d ₅ ) output from the second image memory (15) is P / S.
Bus driver circuit that is intermittently timed through the converter (16)
The first image memory via the P / S converter (7) by (19)
You will be prompted to enter (8).

The output image signal (d ₂ ) of the first image memory (8) is also input to the contour line extraction circuit (20). The contour line extraction circuit (20) is, for example, a well-known one based on a differential method, extracts a required contour line, and outputs 1-bit contour line data (f ₁ ) indicating the presence or absence of the contour line.

The contour line extraction circuit (20) also receives the image signal (d ₆ ) output from the CPU (11), and the image signal (d ₆ ) also causes
The contour data (f ₁ ) can be output.

Although the input signal format is the image signal (d ₂ ) is a parallel format and the image signal (d ₆ ) is a serial format, the amount of the image signal input at one time is one pixel. However, since it is possible to convert to a required signal format by inputting the same bit, either parallel format or serial format may be used.

In the contour line extraction circuit (20), an image signal of any one color of the input three-color image signal is sequentially and selectively used, and the output contour line data (f ₁ ) is the first control signal. The data (f ₁ ) is sent to the memory (21) and recorded at the same address as the image signal (d ₂ ) which is the basis for extracting the data (f ₁ ). That is, the first image memory (8), the second image memory (15), the first control memory (21), and the second control memory (23) described later have the same address arrangement. . The first control memory (21) is an R / W (read / write) control circuit that controls the reading and writing of data.
It has (22).

Further, a second control memory (23) for recording data for the same purpose as the first control memory (21) is provided. The control memory (23) includes an area address generation circuit (24).

The area address generation circuit (24) controls reading / writing of the second control memory (23) and
Under the control of the PU (11), data (f ₂ ) corresponding to the contour line data (f ₁ ) is generated over a required area of the address space, and the data (f ₂ ) is controlled by the second control. memory
Record to (23).

The first and second control memories (21) and (23) both record a pixel that needs correction and a flag signal that specifies an area that needs correction in correspondence with an address.

Also, if you want to process multiple correction items at once,
The correction items, for example, the contour portion correction, the color correction of the pixel designated in advance, the correction by the mask or window area designation, the control memory for each correction item in the predetermined correction region, You may make it record the flag signal of.

Addressing of the pixel signal and area flag signal that need to be corrected is automatically performed by arithmetic processing by the contour extraction circuit (20) and the CPU (11), and when the light pen (28) is used.
In some cases, it is performed manually by tracing the contour with, for example. A cursor line generation circuit (25) is provided to check the position of the flag signal, and the color monitor (18a)
The display timing signal of 1 is fetched from the timing generation circuit (4), and the signal is input to the data selector (10).

Addressing of the cursor line is performed by inputting an input signal from any one of a keyboard (26), a data tablet (27), a light pen (28), a joystick (29), etc. through the input port (12a).

The modified image signal (d ₇ ) is sent to the output port (12b)
Alternatively, from the second image memory (8) (15) to another image processing device such as a color scanner (30) and an electronic editing device (3).
A data transfer circuit (32) for sending to 1) is provided.

The data transfer circuit 32 may be composed of a standardized general interface (for example, RS-232C or the like), or may be provided with an acoustic coupler or a modem so that it can be connected to a telephone line.

Further, the contents of the first or second image memory (8) (15) can be recorded on a floppy disk (33) or a hard disk or a magnetic tape (not shown), and buffering during correction work, or It can also be used to transfer data to another image processing apparatus.

The S / P converters (7) (14) and the P / S converters (9) (16) are for writing and reading signal formats (serial signals) of the first and second image memories (8) (15). Or, it is a conventional means for matching parallel signals).

Although a plurality of timing pulses corresponding to each device are output from the timing generation circuit (4), it is shown as one timing line (Te) because it is complicated in the drawing, and the timing means of the conventional means is used. Is omitted.

Note that (A _T ) is the address bus of the timing generation circuit (4),
( _AC ) indicates the address bus of the CPU (11), and ( _CC ) indicates the control bus of the CPU (11).

Hereinafter, in the configuration diagram of the image correction apparatus shown in FIG. 1, various data, addresses, timing signals and the like will be described as passing through various transfer routes according to the operation content.
It is assumed that a circuit for enabling the bus line is provided in advance at the input of each block according to a command from the CPU (11) in order to take in data, address, timing signal, etc. to the block to be operated.

An example of the circuit is shown in FIG. An action is for a process
For example, if the first control memory (21) is used, the data, address, and timing lines of the first control memory (21), that is, the portion shown as the input in FIG. 2, becomes the tristate buffer. The CPU (11) is given a 1 to the CPU data bus to enable all the lines,
Means the CPU port signal by the I / 0 instruction of (11).

Then, the D latch flip-flop outputs 1 to the Q output, enables the tri-state buffer, and transmits the input signal to the first control memory (21).

On the other hand, in the other processing, the D latch flip-flop is set to D = 0.
By applying and resetting, the input signal and the circuit are disconnected. The following description will be made on the premise that the CPU (11) enables and disables these buffer circuits and buffers prior to processing.

Next, an example of correcting the color cast shown in FIG. 3 will be described.

In general, the color cast often appears on the right side of the outline of the pattern, as shown in FIG. 3A. However, the color cast does not always appear only on the right side of the outline of the pattern.

Therefore, in many cases, the color cast can be corrected by replacing the color cast with the color of the pattern adjacent to the right side of the color cast. An example of replacing with the color of the picture adjacent to the right side of the color cast will be described below.
It is also possible to find an appropriate color from any of the colors around the color cast or the entire pattern and replace it with that color.
If there is no suitable color to replace the color cast in the same screen, replace it with the output signal from the color signal generator (13).

In FIG. 3A, the horizontal line portion is a color cast, and this portion (color cast) should be originally the same as the color of the vertical line portion. Therefore, when the color cast area is automatically determined, the contour of the color cast is obtained using a known differentiation method, and when manually performed, the contour of the color cast is traced with the light pen (28) and the color cast is performed. Second image memory within the outline of the fog
The addresses of (15) are obtained, and the density data of the addresses of all the memories are replaced with the density data of the vertical line portion. An example of such modification is shown in FIG. 3B.

When the contour of the color cast is automatically obtained, if the whole screen is differentiated, many contour signals are obtained, and it is unclear which one is the target. Therefore, as shown in FIG. (R), data tablet (27), light pen
It is more efficient to specify with the joystick (29) or the like (28) and differentiate the image signal only within the specified color cast candidate region (R) because only the necessary contour signal is obtained.

FIG. 4 shows a data selector (10), which is constituted by a known tri-state buffer (for example, SN74126 manufactured by Texas Instruments, USA) or the like, and stores the image signal of the first image memory (8). To store in the second image memory,
Write the cursor to the second image memory (15),
The operation of writing the data from U (11) into the second image memory (15) is performed.

FIG. 4 shows a specific example of the data selector (10R) for processing the red (R) image data in the data selector (10).

The data selectors (10G) and (10B) that process green (G) and blue (B) image data have the same structure as the data selector (10R), and the signal relationship is also color-dependent, so illustration is omitted. To do.

The bus driver (45) input is red in the first image memory (8).
(R) is connected to a bus line (50) that sends read data (RD ₁ ), and its output is connected to a bus line (51) that sends data to the input side of the second image memory (15). .

The input of the bus driver (46) is the bus driver (47) (48) (4
9) is connected to the common output line (52), and its output is connected to the bus line (51).

The bus driver (47) inputs the color signal generator (13) to the bus line (53) that sends out cursor color data (RD ₂ ) for cursor display, and the bus driver (48) input line generates the color signal The input of the bus driver (49) to the bus line (54) which sends the correction color data (RD ₃ ) for correction from the container (13) is C
The output port (12b) of the PU (11) is connected to the bus line (55) which sends out the output data (RD ₄ ) of the CPU (11).

The enable terminals of the bus drivers (45) and (46) are controlled by the output of the AND gate (56), and the enable terminals of the bus driver (46) are connected via the inverter (57). The outputs of 45) and (46) are alternately enabled.

The input of the AND gate (56) is the first image memory on one side.
Read pulse (P ₁ ) of (8) is input, and the other input is
NOR gate (7) to enable the output of the bus driver (46)
The output of 8) is connected.

The NOR gate (78) has three inputs, and the output of the OR gate (58), the output of the OR gate (59), and the CP
When U (11) puts data on the output port (12b), it inputs a data transmission pulse (P ₅ ) indicating that the data is valid.

The cursor designating pulse (P ₂ ) and the color correction designating pulse (P ₃ ) are input to the input of the OR gate (58).

The input of the OR gate (59) is the first control memory
Image correction flag (F ₁ ) read from (21) and image correction flag read from the second control memory (23)
(F ₂ ) and the CP output by the CPU (11) at the address in or around the center of the cursor when correcting the color with the cursor
Input U output pulse (P ₄ ).

The outputs of the OR gates (58) and (59) are logically ANDed by the AND gate (60), and the output of the AND gate (60) is the OR gate (61).
To the OR gate (62) via the inverter (79).

The data output pulse (P ₅ ) is input to the other input of the OR gate (61) through the inverter (63), and the OR gate (61) is input.
The output of is input to the enable terminal of the bus driver (48).

The input of the OR gate (62) and the output of the OR gate (58),
The output of the inverter (79) and the output of the inverter (63) are input, and the output of the OR gate (62) is input to the enable terminal of the bus driver (47).

The data output pulse (P ₅ ) is directly input to the enable terminal of the bus driver (49).

When the data transmission pulse (P ₅ ) enables the output of the bus driver (49), the CPU (11) outputs the output data (RD ₄ ) to the bus line.
(51), the pulse (P ₅ ) is inverted by the inverter (63), and the bus driver via the OR gates (61) (62).
The outputs of (48) and (47) are high impedance.

When the bus drivers (47) (48) (49) described below are valid for output, the pulse (P ₂ ) (P
₃ ) (P ₄ ) (P ₅ ) (F ₁ ) (F ₂ ) is read pulse (P ₁ ) through NOR gate (78), AND gate (56) and inverter (57). Output of the bus driver (46) to enable the data of the bus line (52) in the second image memory regardless of
I am sending it to (15).

The image correction (F ₁ ) or (F ₂ ) or the CPU output pulse (P ₄ ) has an AND gate (60) or an OR gate (P ₂ ) only when the cursor designation pulse (P ₂ ) or the color revision designation pulse (P ₃ ) has The output of the bus driver (48) is enabled via 61), at that time, the bus driver (48) puts the corrected color data (RD ₃ ) on the bus driver (52), and the output of the AND gate (60) is the inverter. The bus driver (47) is set to high impedance via (79).

The cursor designating pulse (P ₂ ) is displayed on the display screen of the CRT (18a) in an arbitrary shape such as a required line or mark, and the keyboard (26) and the data tablet (2
7), it occurs so that the display position can be freely changed with the joystick (29), etc. In the case of normal coordinate designation, it occurs at the timing of displaying a cross-shaped cursor of ten characters.

The cursor line is drawn horizontally and vertically with the target address as the center, and the line has a slight width. When correcting the color by specifying the cursor,
CPU output pulse (P ₄ ) by the CPU (11) in the center address unit or in the area unit with the center address as the center
Is generated and the color can be manually corrected.

Whether the color is corrected or not, and whether it is an address unit or an area unit can be designated from the keyboard (26).

The color correction designation pulse (P ₃ ) is stored in the control memory (21) (23).
This pulse (P ₃ ) is output automatically for data transfer between memories that require color correction.

For the memory-to-memory transfer in which the color correction pulse (P ₃ ) is output, the control memory (21) or (23) is specified at the same address as the first image memory (8), and at this time, the color correction flag (F _At the address with ₁ ) or (F ₂ ), the read data (RD ₁ ) and color correction data (RD ₃ ) are exchanged, and the second image memory
Record to (15).

The cursor color data (RD ₂ ) and the color correction data (RD ₃ ) are generated by the color signal generator (13) as desired color data.

FIG. 5 shows a specific example of a color signal generator (13) for correcting color cast and color signal generation of cursor color. Color correction data (RD ₃ ), (GD ₃ ), (BD ₃ ) are set by potentiometers (64), (65), (66), and the output voltage is set to A / D converter (68), ( After being converted into digital signals having the same number of bits as the image data by 69) and (70), they are input to predetermined input terminals of the data selectors (10R) (10G) (10B) for each color of the data selector (10).

The cursor color data (RD ₂ ) (GD ₂ ) (BD ₂ ) can also be set using the same potentiometers (64) (65) (66) for color correction data (RD ₃ ) (GD ₃ ) (BD performed using the interval of setting of _3), the output voltage is the a / D converter (68) (69) (70), for example, converted into a digital signal of the same number of bits as image data, a latch ( 75) (76) (77), and by the command of the CPU (11), temporarily store it, and the predetermined input of the data selector (10R) (10G) (10B) for each color of the data selector (10) Input to the terminal.

It should be noted that human memory colors such as human skin color, green of plant, and blue of sky are stored in advance in a ROM (Read Only Memory) or the like, and a data selector (10) is used as necessary from a keyboard (26) or the like. It is convenient if you can output to.

〔The invention's effect〕

The present invention has the following effects by being configured as described above.

When determining the contour of a color cast in video platemaking, the color cast candidate area is partially specified in the monitor display image, and the color cast of the contour portion is detected only for the image in the specified color cast candidate area. , It eliminates the inconvenience that many contours other than the target contour are extracted and the target contour is unknown, such as when detecting the color cast of the contour from the entire image, and it is very efficient to correct the color cast. It can be carried out.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image correction device embodying the present invention, FIG. 2 is a diagram showing an embodiment of a bus line driver circuit in FIG. 1, and FIG. 3A is an NTSC system TV. FIG. 3B is a diagram showing the state of occurrence of color cast in the image, FIG. 3B is a diagram showing the state of the image when the color cast is corrected, and FIG. 4 is a diagram showing an embodiment of the data selector in FIG. FIG. 5 is a diagram showing an embodiment of the color signal generating circuit in FIG. (1) TV receiver, (2) TV camera (3) VTR, (4) Timing generation circuit (5) NTSC decoder, (6) A / D converter (7), (14) S / P converter, (8), (15) Image memory (9), (16) P / S converter, (10) Data selector (11) CPU, (12) Input / output interface (12a) input port, (12b) Output port ( 13) Color signal generator, (17) D / A converter (18) CRT controller, (18a) CRT monitor (19) Bus driver circuit, (20) Contour line extraction circuit (21), (23) Control memory ( 22) R / W control circuit, (24) Area address control circuit (25) Cursor line generator, (26) Keyboard (27) Data tablet, (28) Light pen (29) Joystick, (30) Color scanner (31 ) Electronic editing device, (32) Data transfer circuit (33) Floppy disk (35), (36), (37) Shift register (38) Adder, (39) Multiplier (40) Subtractor, (41) Comparator (42) OR gate, (43) Latch (44) Numerical value setter (45), (46), (47), (48) Driver (50), (51), (52), (53), (54), (55) Bus line (56), (60) AND gate, (57), (63), (79) Inverter (58 ), (59), (61), (62) OR gate (64), (65), (66) Potentiometer (68), (69), (70) A / D converter, (75), (76) , (77) Latch (78) NOR gate

Claims (1)

[Claims] 1. A color separation plate for printing based on a video signal composed of three color image signals of red, green and blue, which is subjected to highlight and shadow setup, color correction and gradation correction. During video plate making for scan recording, the image based on the video signal is displayed on the monitor, the color cast candidate area in the display image on the monitor is partially specified, and the density difference between adjacent pixels in the image in the specified area is specified. Depending on the size of the pattern, the outline part of the pattern is extracted and the color cast of the outline part is detected, and the color cast of the detected part is output as the color of the pattern in the display image or the output signal from the color signal generator. A method for color correction in a video plate making apparatus, characterized in that