JPH03229569A - Color picture input device - Google Patents

Abstract

PURPOSE:To realize the color picture scanner of high resolution for all three colors by using the reading system of the high resolution for only a monochromatic one channel portion in addition to the color input system of low resolution. CONSTITUTION:Only a standard color picture is read by a high resolution, and the other two colors are read from the output of the separation system of the low resolution, and the picture signal of the high resolution for all three colors is generated. An original picture 1 is three-color-separtion-scanned first by the resolution coarser than a prescribed picture element in order to calculate a parameter, and it becomes the coarse pictures 2, 3, 4 of R, G, B respectively. Next, the approximate solutions of the parameter [r0, r1] of red and the parameter [b0, b1] of blue are derived for every block from the coarse pictures 2, 3, 4 of R, G, B. Next, the signal of the high resolution for all three colors is obtained by using the parameters and the standard color picture signal of the high resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color image input device that uses the correlation of three color signals to input gold color separation of a high-definition color image when inputting color image information. It is.

2. Description of the Related Art It is well known that in conventional color scanners and color facsimile image feeders, RGB a color signals are separated and scanned using a color separation system in which each color has a predetermined resolution.

In particular, color scanners for printing plates require high-definition color separation, and are therefore equipped with high-resolution and expensive reading and scanning systems.

Recently, high-definition, high-quality images are also required for color copying machines and desktop electronic publishing, making high-resolution color manual equipment essential.

Problems to be Solved by the Invention For this reason, conventional color scanners for plate making have generally been mechanical scanners equipped with a highly accurate color separation optical system on a precise drum scanning mechanism. Not only was it expensive, but its reading speed was also slow. In addition, as an electronic scanner, there is an image input device using a CCD solid-state sensor, but for color applications, high-definition sensors are used in three magnolia rows for each color, or a mosaic filter for three-color separation is used. A high-density color sensor was required.

The present invention uses new signal processing means to improve the conventional high-definition 3
This simplifies the color separation scanning system and aims to realize high-quality image input without requiring a high-definition reading mechanism for each of the three colors as in the past.

Means for Solving the Problems In order to achieve the above object, the present invention provides a monochrome image reading means for separating and scanning a color original image at high resolution, and a color image reading means for separating and scanning a color original image at a lower resolution than the monochrome image reading means. a reading means, a correlation calculation means for calculating a correlation characteristic of an output signal of the color image reading means, and a color conversion means for converting the output of the monochrome image reading means into a color signal using the output of the correlation calculation means. It was established.

According to the above-mentioned configuration, the present invention first calculates parameters using low-resolution three-color separation signals, and then uses the parameters and high-resolution reference color image signals to obtain high-resolution signals for all three colors. .

Example The principle of the present invention will be explained below.

Figure 2 shows a specific example of the correlation characteristics of the three color signals used in the present invention. The red (R
), green (G), and blue (B) The cross-correlation coefficient between the RGB three color separation signals for each partial region is 95% or more between adjacent channels of R and G, and G and B, respectively. R
An extremely strong correlation of around 90% has been observed between both end channels of and B. Such correlation characteristics of three color signals within a partial area are observed in other images as well, and for example, in Japanese Patent Application No. 62-300716, this is utilized to Select one color, for example, the G signal, as the reference color, and use the R and B signals of the other two colors as the G signal.
A method of dependent representation as a function of a signal is described.

Here, as the simplest function, R and B are each G
If it is expressed by the linear equation of, in a certain subregion,
R, G, at sampled coordinates (i, j)
Each pixel value of B is R1j* G Ij+Bij
When Rij = rl Gij + rO-(1
) Bij Yu bl Gij + bo
... Approximate by (2).

As a result, all RGB signals are described using G1 color, which is the reference color, and the three color information of the original image is converted into the reference color image [
Gij] and parameters [rl, ro] and [bl, b
□]. Here, it is not necessary to extract the parameters for each pixel, but it is sufficient to roughly extract them for each partial region. By using this, it is possible to obtain high-resolution three-color image signals using a low-resolution color separation system. It becomes possible to form. That is, the present invention attempts to generate high-resolution image signals for all three colors by reading only the reference color image at high resolution and using the outputs of the separation system for the other two colors at low resolution.

Furthermore, according to the above-mentioned Japanese Patent Application No. 62-300716, the screen is divided into MXM pixels (M and N are positive integers), each block is treated as a partial area, and the parameters are set for each block. (1) and (2) and the original pixel value Ri
A method is described in which the mean squared error between j and Bij is determined to be minimized. Calculation of the parameters requires calculation of the minimum squared error method using all pixels of the block.

For example, all MXN red pixels R1j in a block
, find the coefficient vector [rO, rl] that minimizes the mean square error MN e r2 = (1/MN )ΣΣ -14-1 (RiJR+j) z (3) with equation (1). requires statistical matrix calculation (4). (However, -1 represents an inverse matrix.

For the coefficient vector [bo, b,], RI of equation (4)
It can be calculated similarly by replacing s with BIj.

) In the present invention, first, the function is limited to a linear equation to simplify parameter calculation. Figure 1 shows the basic configuration of the present invention. First, parameters are calculated using low-resolution three-color separation signals, and then parameters and high-resolution reference color image signals are used to calculate all three colors at high resolution. The flow of signal processing to obtain the signal is illustrated.

In FIG. 1, in order to calculate parameters, an original image 1 is first scanned for three color separations at a coarser resolution than a predetermined pixel, resulting in rough images 2.3.4 of R, G, and B, respectively. Here, when the coarse image is divided into blocks of MXN pixels, it is decomposed so that at least two or more coarse pixels are included in one block. Figure 3 shows an example of the decomposition unit for obtaining such a coarsely decomposed image. 2.N/2) The case of coarse decomposition in pixel units is shown. Similarly, 32 and Oha (M/2).

N) This is a case where two coarse pixels are included in each block by coarse decomposition in pixel units and (M, N/2) pixel units.

Next, from the R, G, B coarse image 2.3.4, the red parameter [rO corresponding to equation (4)] is calculated for each block.

rl] and blue parameters [bo, b1].

That is, for the red parameters, rO and rl
In order to solve the two unknowns, it is necessary to set up two simultaneous linear equations, and for this purpose, it is sufficient to have at least 2@ or more coarse pixel data. Strict calculation of equation (4) requires all pixel values within a block at a predetermined resolution, but in the present invention, coarse pixels are used instead for this calculation to reduce the amount of calculation. Note that Equation (4) includes a calculation process for calculating the integrated amount for the coordinates (i, j) with respect to the pixel values Glj and Rlj at a predetermined resolution. Therefore, the term corresponding to this integrated amount is substituted with the value of the coarse pixel.

Therefore, within each block, two coarse pixel values for R, G, and B are (Rx, Ry), (Gx, Gy)',
(Bx.

By), then for ro and rl, the first (1st
), the following simultaneous one-medical equations are established.

Rx = r I Gx + rO---(5) Ry
= r I Gy + ro ・
-(6) That is, solve this instead of equation (4) and get ro-(RxGy-RyGx)/(Gy-Gx)
17) rl = (Rx - Ry) / (Gx - G
y) −(8) is obtained.

Similarly for bo and bl, Bx=bl Gx + bO...(9) By=bIG
By solving y+bO...(10), we can easily obtain bo-(BxGy-ByGx)/(Gy-Gx)
...(11) b 1 = (Bx - By) /
(Gx −Gy) (12) is obtained.

Calculation of coefficient parameters using coarse pixels as described above is extremely simple, and real-time calculations can be performed using an electronic circuit.

Next, FIG. 4 shows another embodiment, based on FIG. 3, configured as a specific color manual device.

In FIG. 4, a color original image 401 is read by a low-resolution color separation camera 402 and outputs an RGB three-color rough image signal 403. For example, 402 is an ordinary color television camera that can color-separate and scan the entire original image at once. The resolution of the camera only needs to have a resolution capability corresponding to the partial area necessary for calculating the parameters described above, and in practice, it may be as coarse as about 8 times the target high resolution.

The three-color coarse image signal 403 is immediately sent to the parameter calculation circuit 4.
05, the four parameters [rO, rl] and [bo, bi] are calculated according to the calculation formulas (5) to (12).
is converted into a parameter signal 407.

On the other hand, 404 is a high-resolution monochromatic line sensor camera that separates and scans one scanning line PQ of the original image with high resolution.

A CCD solid-state image sensor or the like can be used for this, and a color separation filter of, for example, green is attached to obtain an image signal of the reference color. A one-dimensional line sensor is suitable for 404 in order to obtain high resolution, but a two-dimensional sensor is of course faster if the resolution is high.

When using a -dimensional line sensor, it is necessary to move the original screen in the direction perpendicular to the horizontal scanning line or move the line sensor camera 404, but this is generally not the case as it is widely used as a solid-state image scanner. It is a technology that exists.

The high-resolution reference color image signal 406 from the licensor camera 404 is guided to the high-resolution color signal reproducing circuit 408 together with the parameter signal 407, and is converted into a high-resolution color image signal equivalent to that of the reference color according to the linear function approximation equation described above. resolution 3 color signals 4
It will be restored in 09.

Effects of the Invention With the above configuration, the present invention uses a high-resolution reading system for only one single color channel in addition to a low-resolution color manual system such as a television camera, thereby creating a color scanner that has high resolution for all three colors. 1, which has a great effect on simplifying and economicalizing equipment that was conventionally complicated and expensive.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a color image input device according to an embodiment of the present invention, Fig. 2 is a diagram showing the concept of the present invention, and Fig. 3 shows a decomposition unit for obtaining a coarsely decomposed image in the same embodiment. The figure shown in FIG. 4 is a block diagram of a color image input device according to another embodiment of the present invention. 1...Original picture, 2,3.4...Rough image, 5.7...
Parameters, 6... dense image, 8, 10... reproduced image, 9... reference color image.

Claims (2)

[Claims] (1) A monochrome image reading means that separates and scans a color original image at high resolution, and a color image reading means that separates and scans a color original image at a lower resolution than the monochrome image reading means,
A color image input comprising a correlation calculation means for calculating the correlation characteristics of the output signal of the color image reading means, and a color conversion means for converting the output of the monochrome image reading means into a color signal using the output of the correlation calculation means. Device. (2) The color image input device according to claim 1, wherein the monochrome image reading means uses a one-dimensional solid-state image sensor, and the color image reading means uses a color television camera.