JPH02274178A - Monochromic processing system for color picture - Google Patents

Abstract

PURPOSE:To attain monochromic processing in which preservation of color information is excellent by using each uniform area of a color picture as a different texture and converting its color separation signal into a monochromic signal. CONSTITUTION:A texture signal depending on the result of quantization of R, G, B signals is valid in a uniform area of a color picture read by a scanner 1 and a conventional dither processing signal is valid in other area. A monochromic processing signal outputted from a synthesis section 5 is printed out by a printer 6 as a hard copy or sent from a transmission section 7 or recorded on a recording medium such as an optical disk or a hard disk by a picture file section 8. Since the uniform area of the color picture is used as a different texture and subjected to monochromic processing in this way, the color information is preserved as the texture and the monochromic processing in which the preservation of the color information of the original color picture is excellent is attained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for converting color images into monochrome.

[Conventional technology]

In monochrome copiers and facsimile machines,
It is necessary to convert color originals to monochrome. Conventionally, this type of apparatus performs monochrome conversion by reading only the shading information of a color document.

[Problem to be solved by the invention]

However, in such a monochrome method, color information contained in a color image is lost. That is, even if the colors are different, the read signal level may be the same, and if the images are reproduced as they are, the difference between the original colors will not be noticeable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for converting color images into monochrome that can preserve color information.

[Means and effects for solving the problem] The monochrome conversion method of the present invention extracts uniform areas from the color separation signals of a color image, treats each uniform area as a different texture, and converts the color separation signals into monochrome signals. It is a converter that expresses one color information as texture, and can preserve color information even after converting to monochrome.

〔Example〕

The monochrome conversion method of the present invention is applicable to hard copy devices and soft copy devices that reproduce color originals as monochrome images, facsimile devices that transmit color originals as monochrome signals, image file devices that file color images as monochrome images, etc. can be applied to

FIG. 1 is a schematic block diagram showing an embodiment of such a device with multiple functions.

Reference numeral 1 denotes a scanner that separates and reads a color original into R (red), G (green), and B (blue), and sends out R, G, and B signals. 2 is a uniform area extraction unit that extracts a uniform area based on each R, G, and B signal; 3 is a texture generation unit that generates a texture for the uniform area; 4 is a Bk (black)
This is a halftone processing section that performs dither processing as a substitute signal for the signal. Reference numeral 5 denotes a synthesizing section that synthesizes the dithered signal and the texture signal to obtain a monochrome signal. 6 is a monochrome image printer, 7 is a transmission unit for monochrome facsimile communication, and 8 is a monochrome image file unit.

FIG. 2 is a block diagram of the uniform area extraction section 2. As shown in FIG.

The uniform area extracting section 2 is comprised of a circuit section 1o for determining the extraction of a uniform area, and a circuit section 11 for generating an index (texture number).

In one circuit section 10, 12 is an R signal processing circuit;
3 is a G signal processing circuit, 14 is a B signal processing circuit,
These have the same configuration except for the input signal, so R
Only the configuration of the signal processing circuit 12 is shown. Reference numeral 15 denotes an AND gate that performs the logical product of the output signals of the respective circuits 12, 13, and 14, and its output signal becomes a detection signal for the uniform area.

In the R signal processing circuit 12, first, in order to correspond to a halftone image, the R signal is smoothed by a smoother 16 using, for example, a 5×5 pixel window, and then the wax circuit 17 and the win
The circuit 18 selects a region near the pixel of interest (for example, 8×8
The maximum value R+max and the minimum value Rwin of the R signal in the pixel window) are detected.

By the subtractor 19, ΔR= R+++ax −Ra1n
is determined, and the comparator 20 compares ΔR with a threshold value 'rh.

When ΔR<Th, the output of the comparator 20 becomes "1".

Similarly, in the G signal processing circuit 13 and the B signal processing circuit 14, ΔG = G mac - G l1in and ΔB = B+max - Bmin are determined, and ΔG<T
The respective outputs are set to 11111 when h and when ΔB<Th.

The other circuit section 11 quantizes each of the R, G, and B signals into several levels, and uses the quantized output as an index signal. In the example shown here, the comparator 21,
R,G by 22.23.

By comparing each B signal with a threshold Th, two-level quantization is performed to obtain a three-bit index. That is, 8 (=23) types of indexes are generated.

In addition, if the configuration is configured to perform 3-level quantization,
It is possible to generate 27 (=33) types of indexes.

FIG. 3 is a block diagram of the texture generating section 3. 25
is a ROM that stores eight types of textures (monochrome patterns) as shown in FIG. 4, and 26 and 27 are counters that are incremented by an X-direction clock X and a Y-direction clock y. In this example, the texture is an 8x8 pattern, so counters 26 and 27 can be 3-bit counters. 3-bit index signal (corresponding to texture number) and counter 2
The 6-bit output signals (X-axis and Y-axis position information) of 6 and 27 become the address signal of the ROM 25, and the signal of the bit specified by the 1 position information of the texture number specified by the index signal is sent to the texture from the ROM 25. Output as a signal.

FIG. 5 is a block diagram of the synthesis section 5. When the output signal (uniform area signal) of the uniform area extractor 2 is '1'', the texture signal passes through the AND gate 29 and is output to the OR gate 3.
0 is output as a monochrome signal. When the uniform area signal is (l OI+), the output of the inverter 31 becomes 11111, so the dithered signal passes through the AND gate 32 and is output from the OR gate 30.

That is, in a uniform area of a color image read by the scanner 1, a texture signal determined by the quantization results of the R, G, and B signals is effective, and in other areas, a normal dither processing signal is effective. Become.

The monochrome signal output from the synthesis section 5 is reproduced as a hard copy by the printer 6 or transmitted to the transmission section 7.
or recorded on a recording medium such as an optical disk or a hard disk by the image file section 8.

In this way, since each uniform area of a color image is made into a monochrome image with a different texture, one color information can be expressed and stored as a texture. Therefore, it is possible to obtain a monochrome hard copy of the original image with clear color differences using the printer 6. Furthermore, even when the monochrome signal transmitted by the transmission section 7 is received by a monochrome facsimile machine, a received document with clear color differences can be obtained. Furthermore, by outputting the image data stored in the image file unit 8 to the printer 6 or a monochrome display device, a reproduced image with good preservation of the color information of the original color image can be obtained.

Note that Y (yellow) and M (magenta) are used instead of RGB signals.
, C (cyan) signals can also be used to similarly perform monochrome conversion.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to perform monochrome conversion with good preservation of color information.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention, and FIG.
3 is a block diagram of the uniform area extracting section, FIG. 3 is a block diagram of the texture generating section, FIG. 4 is a diagram showing an example of texture, and FIG. 5 is a block diagram of the synthesizing section. 1... Scanner, 2... Uniform area extraction unit, 3.
... Texture generation section, 4. Halftone processing section, 5.
...Composition section, 6.Printer, 7.Transmission section,
8... Image file section. Figure 3 (Temosu+Ya○) (Tegizu-Fy1)

Claims (1)

[Claims] (1) Extract a uniform area from the color separation signals of a color image,
A method for converting color images into monochrome, which is characterized by treating each uniform area with a different texture and converting the color separation signals into monochrome signals.