JPH01238937A - Color image processor - Google Patents

Abstract

PURPOSE:To reproduce various types of color image signals with correct colors by providing image input means for inputting a plurality of types of color image signals, converting means for converting the input color image signal to a color image signal according to a predetermined standard, and image forming means for forming a color image. CONSTITUTION:A CCD line sensor 103 color-separates a reflected light from a color original 102 to three primary colors of R, G, B to read them. A/D converters 105-1-3 convert analog (r), (g), (b) signals into digital R1, G1, B1 data. Data selectors 106-1-3 input various types of color image data to image data processors 107-115. A color converter 108 so converts input various types of color image data (RGB, YIQ, etc.) to match the processors 111-114. A density converter 111 converts intensity R2, G2, B2 data into density Y1, M1, C1 data. A printer 115 always record an image of correct color according to gamma- offset C3, M3, Y3, K3 data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image processing device, and more particularly to a color image processing device that reproduces correct colors of an original image.

[Prior Art] Conventionally, this type of device uses an image input means (for example, a CCD sensor) and an image output means (for example, a laser beam printer).
is fixed, and the correct colors of the original image are reproduced by constant (fixed) signal processing during this period.

FIG. 2 is a block diagram of a conventional color image processing device.

In the figure, 201 is a CCD line sensor that separates reflected light from a color original (not shown) into RlG and B three primary colors and reads them. 202 is an A/D converter that converts analog r, g, b signals into digital R, G, B data. 203 is a logarithmic conversion circuit, which converts brightness R, G, B.
Convert the data to density C+, M+, Y+ data.

204 is a masking circuit, and the above-mentioned C1゜M, ,Y
, performs color correction (masking) processing on the data.

The masking process is performed, for example, by linear transformation of equation (1).

Here, alJ: masking coefficient 205 is a black component extraction circuit, and color-corrected C2, M
2. Detect the minimum value (achromatic color component) kl in the Y2 data and output C2, M2, Yt, kr data. 206 is an under color removal (UCR) circuit, and C2
, M2, and Y2 data according to equation (2).

C3=C2kc K+ M3=M2 k-K+ Y3=Y2 ky K+ Kz=kkk+ (2) Here, kc, -kM, ky, kk: UCR coefficient, U
The CR coefficient takes a value between O and 1, and when the UCR coefficient is 1, it is called "full black" or 100% UCRJ. 207 is a gamma (γ) offset circuit, which removes the undercolor. : Perform gamma offset calculation using equation (3) on the VI3, Y3, and K2 data to match the printer characteristics (toner, ink, etc.).

C4:Gc(Cs-βC) M4=02(M3-C4) Y4=αY(Y3-βY) K 3” Q K(K 2-βK) (3
) Here, Gc"-ak: Gamma coefficient β. ~ βk The two-offset straight 208 is, for example, a laser beam printer, and the gamma coefficient
Offset C4. M4. Y4, the correct color of the original image is reproduced and recorded according to the 3 data.

[Problems to be Solved by the Invention] By the way, today's color signal sources are many and varied. For example, a television image signal Y of the NTSC system.

1, Q, and color image signals based on computer graphics. However, in traditional configurations, a dedicated signal source (
TV image signal Y other than CCD, etc.), 1. Not only is it not possible to input color image signals such as Q or computer graphics, it is also not possible to reproduce them in the correct colors.

The present invention is intended to eliminate the above-mentioned drawbacks of the prior art, and its purpose is to provide a color image processing device that reproduces various color image signals in correct colors with a simple configuration.

[Means for Solving the Problems] In order to achieve the above object, the color image processing device of the present invention includes an image input means for inputting a plurality of types of color image signals, and a color image processing device for inputting the input color image signals according to a certain standard. The outline of the image forming apparatus includes a converting means for converting into a color image signal according to the following, and an image forming means for forming a color image according to the converted color image signal.

Preferably, the conversion means converts the input color image signal into R, G, and B signals conforming to the R, G, and B signals of the NTSC system.

Further, in order to achieve the above object, the color image processing device of the present invention includes an image input means for inputting a plurality of types of color image signals, and converts the input color image signals into R, G, and B signals according to a certain standard. a first converting means for converting, and a second converting means for converting the converted R9G, B signals into Y, M, C signals.
converting means, black forming means for forming a signal of an achromatic color component based on the converted Y, M, and C signals;
a masking means for inputting signals to M, C, and performing masking processing including undercolor removal and inking by 4×4 matrix calculation;
The outline of the apparatus is that the image forming apparatus is provided with an image forming means for forming a color image according to a signal.

[Operation] In the above configuration, the image input means receives a plurality of types of color image signals (for example, R, G, B signals, and Y signals.

1, Q signal, etc.). The converting means converts the input color image signal into a color image signal conforming to a certain standard. Preferably, the converting means converts the input color image signal into R, G, B signals according to R9G, B signals of the NTSC system.

The image forming means forms a color image according to the converted color image signal.

Further, in the above configuration, the image input means inputs a plurality of types of color image signals (for example, R, G, B signals, Y, I, Q signals, etc.). The first conversion means converts the input color image signal into a certain standard (for example, R, G, B signals of the NTSC system).
Convert to R, G, B signals according to the following. The second conversion means converts the converted R, G, and B signals into Y, M, and C signals. The black forming means forms an achromatic color component signal based on the converted Y, M, and C signals.

The masking means inputs the Y, M, and C signals and performs masking processing including undercolor removal and inking by 4×4 matrix calculation. The image forming means forms a color image on the masked Y, M, and C signals according to the signals.

[Description of Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a color image processing apparatus according to an embodiment of the present invention. In the figure, 116 is a beamer section, which is a color image signal source exclusive to the apparatus of this embodiment.

In the reader section 116, a light source 101 illuminates a color original 102 placed on an unillustrated original table. 10
3 is a CCD line sensor that separates the reflected light from the color original 102 into three primary colors of R, G, and B and reads them.

A sample and hold circuit 104 samples and holds the analog r9g and b signals output from the CCD. 105-1 to 105-3 are A/D converters which convert analog r, g, b signals into digital R1, G1 . Convert to B+ data.

Data selectors 106-1 to 106-3 enable input of various color image data to subsequent image data processing units 107 to 115. That is, when each contact of the data selectors 106-1 to 106-3 is on the A side, R+, G+, B+ data from the reader section 116 is input,
When the contact is on the B side, from the connected device 117 to the connector 12
2, various color image data are input.

This connected device 117 includes, for example, a frame memory 118 for one image, and (7)Y from the VTR 119 or TV camera 120 connected thereto.

It converts I, Q signals into Y, I, Q data and stores them, or stores color image data from the graphic computer 121.

Reference numeral 108 denotes a color conversion circuit, which converts various input color image data (RGB, YIQ, etc.) so as to match them with fixed processing circuits 111 to 114 at the subsequent stage.

Here, various types of color image data to be input will be considered.

First, in the reader section 116, the CCD sensor 1
r+, g, when reading any color original i in 03
, b+image signal is given by equation (4).

=lD, (λ) ・S (λ) ・R(λ)dλg
+ =lDG(λ)・S(λ)・R(λ)dλI =lD,(λ)・S(λ)・R(λ)dλWhere, S(λ)・Spectral energy of the light source R(λ) : Spectral reflectance of original image i DR(λ), D(1(λ), Dll(λ)): Spectral sensitivity of CCD sensor coated with RGB color separation filters Figure 3 (B) shows the spectral sensitivity characteristics of the CCD sensor. DI+
(λ), DG(λ), and DB(λ).

On the other hand, when the standard white original W is read by this CCD sensor 103, the r w , gw , k)w signals are (5)
It is given by Eq.

w =lD11(λ)・S(λ)・W(λ)dλ W =ID, 3 (λ)・S(λ)・W(λ)dλw lDa(λ)・S(λ)・W(λ) dλHere, W(λ), the spectral reflectance of standard white.The A/D converters 105-1 to 105-3 use an appropriate method to compare the rl+, , b, signals with other types of color image data. It is necessary to convert (standardize) it into digital data with a certain number of bits. Therefore, r+, g+, b+ scratch signal rw.

gw, k) normalized by the w signal and A/D converted.

That is, R+ provided by the reader section 116.

G+ and B+ data are given by equation (6).

R+=f"t/rw G+:g+/gw B+=b l/b w (6) Next, in the connected device 117, Y, I of the NTSC system
, consider Q data. Y is luminance data, ■ and Q
is color data. This Y.

The I and Q data are calculated according to the equation (7) using the corresponding R2°G2.
Can be converted to B2 data.

Specifically, in this process, the 3×3 matrix coefficients of equation (7) are stored in memory (2) 110 in advance, and the color conversion circuit 108 converts the Y, I, and Q data according to equation (7). Ra,
Convert to G2 and B2 data.

Figure 3 (A) shows the ideal spectral sensitivity characteristic of the NTSC system, I
' (λ), D, ' (λ), D8° (λ) 0As is well-known, in the NTSC system, colors with lower saturation than pure colors are used in the three primary colors to match the chromaticity of practical phosphors. It is stipulated that The R2, G2, and B2 data converted using the above equation (7) are R, G, and B data in this NTSC system.

By the way, this R2, G2, B2 data is from the above NTS
Ideal spectral sensitivity characteristics of C method DR' (λ), DG' (
λ), DBo(λ), and the above equation (4) and (5
) expression, the subject (for example, a color original 1.
It is considered that the following relationships (8)2 to (1o) hold with respect to the standard white original W).

=I D, +□(λ)・S(λ)・R(λ)dλ=iD
a'(λ)・S(λ)・R(λ)dλ=lD11'(λ
)・S(λ)・R(λ)dλR.

=iDR1λ) ・S (λ) ・W (λ)dλG
.

lDG' (λ)-3(λ) ・W(λ)dλw = ID8° (λ) ・S (λ) ・W (λ)d
λR2"R1/Rw G2"Gl/GW B2'Bl 78w (
10) Therefore, if this R2, G2, B2 data and C
If one of the R, G, B data of the CD 103 is converted to be equal to the other, the subsequent color processing system 1
Even if 11 to 114 are constant (same), correct colors can always be reproduced.

Therefore, in this embodiment, for example, the NTSC system is set as the standard, and other types of color image data are converted into RGB of the NTSC system.
Convert to image data.

For example, the R+, Gr, and B+ data of the reader section 116 are linearly converted according to equation (11) to become R2, Gz, and B2 data conforming to the NTSC system.

Here, a: Color conversion coefficient Specifically, in this process, the 3×3 matrix color conversion coefficient a of equation (11) is stored in advance in the memory (1) 109,
The color conversion circuit 108 has R1, Gr,
B+ data to Rz, Gi.

Convert to B2 data.

Note that when color image data is input manually from an external graphic computer or the like, linear conversion can be performed to match RGB data of the NTSC system using the same concept as described above. For this purpose, memory (1) 109 and memory (2) 110
Matrix coefficients are prepared according to the characteristics of each color image data.

Reference numeral 111 denotes a density conversion circuit, which converts luminance R, G2 . B, data as concentration Y+, M
Convert to Ct data.

112 is a black component extraction circuit, Y+, M+.

Detect Y+ at the minimum value of C1 data.

Output + data to Ml, Cr. 113 is a masking circuit that performs color correction of + data on Yl, M+, C1.

Specifically, a masking operation is performed according to equation (12).

At this time, if a41 to a43<O is selected, the undercolor is removed. Also, if a44>O is selected, ink will be added.

The UCR ratio is determined by the magnitude of the coefficients 84+ to a44. In this way, conventional masking processing, undercolor removal, and inking processing can be performed in one matrix operation. 1
Reference numeral 14 denotes a gamma (γ) offset circuit, which adjusts to the characteristics of the printer 115 by calculating equation (13).

C5 = γc (C2 - β.) M3 = γM (M2 - β, 4) Y3 = γY (Y2 - βY) K3 = γ (K2 - βK) (l 3) Here, γC ~ γ: Gamma coefficient βC to β ・The offset value 115 is, for example, a laser beam printer, and the gamma
Offset C3. M3. Always record images with correct colors according to Y3°K3 data.

[Other Examples] Although equation (11) in the above-described example shows color conversion using a 3×3 matrix, the present invention is not limited to this. Other transformations involving higher-order terms are also possible. For example, in addition to the input R1, G+, and B+ data, the NTSC system can be converted to It becomes possible to perform conversion closer to the RGB signal according to the ideal imaging characteristics.

[Effects of the Invention] As described above, according to the present invention, the image input signal can be converted and subsequent circuits can be shared, so that correct color reproduction can always be achieved with a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a color image processing device according to an embodiment of the present invention, Fig. 2 is a block diagram of a conventional color image processing device, and Fig. 3 (A) shows ideal spectral sensitivity characteristics according to the NTSC system. FIG. 3(B) is a diagram showing an example of the spectral sensitivity distribution of the CCD sensor 6. In the figure, 116...reader section, 101...light source, 10
2... Color original, 103... CCD line sensor, 104... Sample hold circuit, 105-1 to 1
05-3...A/D converter, 106-1 to 106-3
...Data selector, 117...Connected device, 118
...Frame memory, 119...VTR. 120...TV camera, 121...computer,
122... Connector, 108... Color conversion circuit, 10
9...Memory (1), 110...Memory (2)
, 111...density conversion circuit, 112...black component extraction circuit, 113...masking circuit, 114...γ offset circuit, 115...printer. Patent applicant: Canon Corporation Wave Length (nml) Figure 3 (A) Figure 3 (B)

Claims (3)

[Claims] (1) An image input means for inputting a plurality of types of color image signals, a conversion means for converting the input color image signal into a color image signal according to a certain standard, and a color image according to the converted color image signal. A color image processing apparatus comprising an image forming means for forming an image. 2. The color image processing apparatus according to claim 1, wherein the converting means converts the input color image signal into R, G, and B signals in accordance with R, G, and B signals of the NTSC system. (3) Image input means for inputting a plurality of types of color image signals, and R, G input means for inputting the input color image signals according to a certain standard.
, a first converting means for converting the converted R, G, B signals into Y, M, C signals; and a first converting means for converting the converted R, G, B signals into Y, M, C signals; K of the achromatic color component
a black forming means for forming a signal; a masking means for inputting the Y, M, C, and K signals and performing masking processing including undercolor removal and inking through a 4×4 matrix operation; A color image processing apparatus comprising an image forming means for forming a color image according to M, C, and K signals.