JPS61105972A - Color picture signal processing method - Google Patents

Abstract

PURPOSE:To enable to reproduce a well-balanced black-and-white picture properly from any color original by forming optimum black-and-white data necessary for forming a black-and-white picture from three-color color separation picture data obtained by a color picture reading device. CONSTITUTION:Input is R, G, B signals 10-12 of 8-bit, and inputted to multipliers 1-3 respectively. Set values k-m of coefficients are inputted to the multipliers. Out of output of multipliers, that is, kR, lG, mB (16-18), kR, lG (16, 17) are added by an adder 4 and 1 bit shifted, that is, halved by a shift register 8. Operation similar to those made in the adder 4 and shift register 8 is made in an adder 9 and a shift register 21, and proper black-and-white picture data are sent out to a black-and-white copying device.

Description

DETAILED DESCRIPTION OF THE INVENTION (Description of the Field) The present invention relates to a color image signal processing method applied to a system in which a color original reading device and a monochrome image printing device are connected.

(Description of Prior Art) Conventionally, a color original image is separated into three primary colors by color separation filters such as B, G, and R, and an optical image is converted into a photoelectric conversion element using a linear solid-state image sensor or the like.

Many color image reading devices have been proposed that obtain quantized image data by converting it into an electrical signal and then performing A/D conversion. The image data obtained here is usually quantized into 6 bits or 8 bits. On the other hand, although there are many color image printing devices that can obtain color printed images based on the color image data corresponding to each color component obtained through the color separation, black and white printing devices are still the most common. It is. By the way, when the color image reading device and the monochrome image printing device are connected, the color image data obtained by the color image reading device is R, G, B (or Y, M,
C).

Since the monochrome printing device is of the 1 type, data conversion is required. At this time 9 For example, R+G+B for black and white signals.

D can be obtained by taking an approximate average of 7-Tera, or by converting the gray component into a black and white component among the color separation components of the same pixel of a color original, but in the former case, for example, if the original is Spectral energy distribution of irradiating illumination Spectral transmission characteristics of a single-color separation filter Depending on the solid-state image sensor and spectral characteristics, depending on the color components of the document, the concentration of certain color components may not be obtained, resulting in an unbalanced black and white image. In the case of post-printing, if the original is composed of primary colors, there is no gray component, so it has the disadvantage that it cannot be printed in black and white.

(Purpose) The present invention was made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a color image signal processing method capable of appropriately reproducing a black and white image in a well-balanced manner for any color original.

(Example of the invention) The present invention will be described in detail below with reference to FIG.

FIG. 1 is a circuit diagram in which the present invention is implemented, and input image data R, G, and B are quantized after color separation, photoelectric conversion, and A/D conversion of the aforementioned color original. 8bi
This is color image data of t. This circuit is a circuit that obtains black-and-white image data D to be printed on a black-and-white printing device from the three types of color image data R, G, and B, and obtains black-and-white image data according to the following formula, that is, by . The circuit will be explained below. Input is 8 bit R, G, B signal 10.11.12
and are each input to a multiplier 1.2°3. The other inputs of each multiplier are input with i and m as coefficient settings.

However, Oak, Q, m≦1, and setting switch 5.
6.7, and therefore the output of the multiplier is also 8.
It becomes a bit. Output of each multiplier.

That is, kR, uG, mB (16, 17, 18) is first k
RllG (16, 17) is added in adder 4 and shifted by 1 bit in shift register 8.

In other words, it is halved. Therefore, output 19 is kRjubunG/
2, which is further sent to the next-stage adder 9 as a signal 18 (=
mB).

The adder 9 and shift register 21 perform the same operation as the adder 4 and shift register 8, and (kR
+iG/2+mB)+2 or D= (kR+iR+2m
B/4) is calculated.

Based on this D, appropriate black-and-white image data is sent to a black-and-white printing device. In addition, it is also possible to adjust the density balance by adjusting the 2m variable to the coefficient setting value according to the exposure illumination, the spectral characteristics of the color separation filter, and the spectral characteristics of the photoelectric conversion element. be.

(Effects) As explained above, according to the present invention, with a simple configuration,
Optimal black and white data required for black and white image formation can be generated from the three color separated image data obtained by a color image reading device, and the input color balance adjustment mechanism can respond to irregularities of 1<1 in a single color image signal. It is possible to form monochrome image data, and when a monochrome image forming device is connected to a color image reading device, a monochrome image can be formed without any problems.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of this embodiment. In the figure, 1 and 2.3 are multipliers, 4.9 is an adder, and 5
, 6.7 are setting switches, and 8.21 is a shift register.

Claims (2)

[Claims] (1) A color method characterized in that a document is color separated using a color separation filter, image signals of each color component are obtained, and black and white density image data is obtained by using a weighted average of the image signals of each color component. Image signal processing method. (2) The color image signal processing method according to claim 1, wherein the weighting coefficient of each color component is arbitrarily variable.