JPH0453343A - Picture reader - Google Patents

Abstract

PURPOSE:To obtain a color picture output without color slurring with arranged gray balance by executing weight mean processing to a color even at a base position with a prescribed ratio together with preceding and succeeding same color data. CONSTITUTION:An interpolation circuit 100 consists of latches 101G, 101B, 101R delaying a signal as required, adders 102G, 102B, 102R adding output signals of multipliers 105G, 105B, 105R multiplying signals delayed by the latches and each constant, and latches 104G, 104B, 104R delaying signals outputted from dividers 103G, 103B, 103R. Weight mean processing is applied to a color even at a base position with a prescribed ratio together with preceding and succeeding same color data at interpolation of position deviation in a same picture element. Thus, a color picture output is obtained without color slurring with arranged gray balance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device used in a color copying machine, etc., and more specifically to an image reading device that reads the color signal of one pixel using three light receiving elements. This relates to a reading device.

[Conventional technology]

Conventionally, one-dimensional or two-dimensional color images have been produced using a color light-receiving element array consisting of light-receiving elements in which three or more color separation filters are arranged per pixel on the light-receiving surface.
In a color image reading device that reads a sequence of color signals that are the color separation filter transmission densities of each pixel, a predetermined complementary operation is performed between adjacent pixels of each color signal in order to correct errors caused by differences in the positions of the light receiving elements. An apparatus (Japanese Unexamined Patent Publication No. 154357/1983) has been proposed.

FIG. 2 is a block diagram of a signal processing unit and a color output unit for color signals read by the image reading unit, and shows an A/C converting the analog color signal 201 read by the image reading unit (not shown) into a digital signal. Correction of variations in the sensitivity of the D conversion circuit 202 and the light receiving element of the digital color signal 203 converted by the A/D conversion circuit 202, uneven illuminance of the light source, offset of the analog system, white transmittance of the color separation filter, etc. A shading/correction circuit 204 that executes a shading/correction operation, an interpolation circuit 206 that executes a predetermined interpolation operation on the standardized color signal 205 after shading correction output from the shading correction circuit 204, and an interpolation operation output from the interpolation circuit 206. The color signal is a luminance signal 209a representing the luminance component of the pixel.
A luminance/chrominance separation circuit 208 separates the luminance signal 209b and 209c into color difference signals 209b and 209c representing the hue components of the pixel, and performs spatial high-frequency enhancement processing on the luminance signal 209a separated in the luminance/chrominance separation circuit 208, and converts the color difference signal into 209b, 20
A filter circuit 210 that performs spatial averaging processing on 9C, and three-color ink amount signals that synthesize corresponding colors with respect to the luminance signal 211a and color difference signals 211b and 211c filtered by the filter circuit 210. 213
a color conversion circuit 212 that converts the ink amount signal 213 converted by the color conversion circuit 212 into a binary ink quantity signal 215; The color output unit 216 reproduces a color image based on the binary ink color signal 215.

The operation of the above configuration will be explained.

A color signal 201 read by the image reading unit is converted into a digital color signal 203 by an A/D conversion circuit 202, and a shading correction circuit 204 corrects variations in sensitivity of the light receiving elements and the like. The color signals 205 standardized by the shading correction circuit 204 are G, -1, B, -1, R, -1, G
n, B7, R,, G a41, B a. The signals are sent to the interpolation circuit 206 in the order of 8 and R7°1.

For these inputs, interpolator 206 calculates B, l −B
, 1, and outputs the interpolated color signal 207 to the luminance/color difference separation circuit 208.

In the luminance color difference separation circuit 208, the interpolated color signal 207
is separated into a luminance signal 209a and color difference signals 209b and 209c, which have low correlation with each other. The luminance signal 209a and color difference signals 209b and 20 obtained in this way
9c is input to the filter circuit 210, and the luminance signal 209
Spatial high frequency enhancement processing is executed for a, spatial averaging processing is executed for the color difference signals 209b and 209c, and the luminance signal 211a and the color difference signals 211b and 211 are
Output c.

Filtered luminance signal 211a and color difference signal 211
b and 211c are input to a color conversion circuit 212 and converted into three color ink amount signals 213.

For example, when a binary output thermal transfer printer is used as a color output device, the ink amount signal 213 is converted into a binary ink quantity signal by a binarization circuit 214, and the color output unit 216 is driven by this signal. to play back the color image.

Further, the configuration of the interpolation circuit 206 described above employs the configuration shown in FIG. 3.

That is, assuming that the input standardized color signal 205 is Xrl, X and l are the latches 301a and 30 which are registers.
1b and 301c by one pixel, and 2Xn +X, 1-IX, 1+2Xll-+ are obtained as signals 304.305 by double multipliers 302a and 302b and adders 303a and 303b. These signals are multiplied by 1/3 by multiplier 306 and switched by selectors 307a and 307b, and signal 308 is Xn itself and is switched by selector 307b. Selectors 307a and 307b are switched by a ternary counter 309, and are switched and connected to signals 305, 308, and 304 according to the inputs B, G, and R, and the above-described interpolation calculation is executed.

[Problems to be Solved by the Invention] However, in the conventional device described above, since weighted average processing is not performed on B, the MTF of G and R deteriorates compared to B, and There is a problem in that the gray balance collapses when the frequency is exceeded.

The present invention has been made in view of the above, and an object of the present invention is to obtain a color image output with no color shift and a well-balanced gray balance.

[Means to solve the problem]

In order to achieve the above object, the present invention uses a color light-receiving element in which each pixel has a plurality of color separation filters arranged on the light-receiving surface, and converts a color image into a string of color signals, which are the transmittances of the color separation filters of each pixel. An image reading device is provided with an interpolation means for interpolating positional deviations within the same pixel, and the interpolation means performs weighted averaging processing on the color at the basic position at a predetermined ratio together with data of the same color before and after it. The present invention provides an image reading device that uses the following methods.

Further, it is preferable that the ratio is a value such that the MTF of each color matches at each spatial frequency.

[For production]

In the image reading device according to the present invention, when a color image sensor in which one pixel is divided by a plurality of color separation filters outputs image data in color order, the image reading device uses a color as a basic position in order to interpolate positional deviation within the same pixel. A weighted average process is also performed on the data of the same color before and after it at a predetermined ratio.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

FIG. 1 is a block diagram showing the configuration of an interpolation circuit used in an image reading device according to the present invention.As for the positioning of the entire device, the interpolation circuit is inserted into the interpolation circuit portion of the block diagram in FIG. . Therefore, the A/D conversion circuit, shading correction circuit, luminance color difference separation circuit, filter circuit, color conversion circuit, binarization circuit, and color output section shown in FIG. Detailed explanation will be omitted since it is redundant.

In FIG. 1, interpolation circuit 100 includes latches l0IG, each of which delays a signal as necessary.

101B, 101R, and the latch 101G.

101B and 101R, and multipliers 105G, 105B, and 105 that multiply the signals by respective constants.
Adders 102G, 102B, 102R that perform addition processing on the output signal from R, and the divider 103G,
103B.

Latch 104 that delays the signal output from 103R
G, 104B, and 104R.

In the above configuration, the operation is such that the color signal 201 read by the image reading section is converted into a digital color signal 203 via the A/D conversion circuit 202,
3, a shading correction circuit 204 corrects variations in sensitivity of light receiving elements, uneven illuminance of a light source, etc., and outputs a standardized color signal 205.

The standardized color signals 205C;, 205B, 205R, which are the outputs of the shading correction circuit 204, are expressed as G□I,B,-,%Rn-1,cn,B,,,R as shown in FIG.
I,,G,,+1,B,,. 1, R7°, and are input to the interpolation circuit 100 in this order.

Each standardized color signal 205G, 205B, 205R is connected to a latch 10IG, 10IB, 10IR, an adder 102G,
102B, 102R1 divider 103G, 103B, 10
3R and latches 104G, 104B, and 104R, the following interpolation calculations are executed.

For the ratio M of B and r in the above interpolation calculation, select the optimal value (for example, 5) so that the MTF of each color matches at each spatial frequency, and also select the same color before and after the reference position color (B). A weighted average process is executed using the above ratio M together with the data.

After the interpolation calculation is completed in the interpolation circuit 100, the interpolation circuit 100 outputs the interpolation color signals 207G and 207B.

207R is output to the luminance/color difference separation circuit 208.

Hereinafter, the signals are transmitted to the filter circuit 210, the color conversion circuit 212.
A color image is reproduced by a color output unit 216 via a binarization circuit 214.

〔Effect of the invention〕

As explained above, according to the image reading device of the present invention, 1
In an image reading device that uses a color light-receiving element in which a plurality of color-separation filters are arranged on the light-receiving surface of each pixel, and reads a color image as a string of color signals that are the transmittance of each pixel through the color-separation filters, positional deviation within the same pixel is detected. The interpolation means performs a weighted average process on the basic position color along with data of the same color before and after it at a predetermined ratio, so there is no color shift and the gray balance is well-balanced. Color image output can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an interpolation circuit in the image reading device of the present invention, FIG. 2 is a block diagram showing the configuration of a conventional image reading device, and FIG. 3 is the configuration of the interpolation circuit shown in FIG. 2. FIG. 4 is an explanatory diagram showing the normalized color signal ' input to the interpolation circuit. Description of symbols 100-interpolation circuit 101G, l0IB. 102G, 102B. 103G, 103B. 104G, 104B. 101 R-latch 102 R-adder 103 R---divider 104 R-latch

Claims (2)

[Claims] (1) In an image reading device that uses a color light-receiving element in which each pixel has a plurality of color-separation filters arranged on the light-receiving surface, and reads a color image as a string of color signals representing the color-separation filter transmittance of each pixel, the same pixel The image reading apparatus further comprises an interpolation means for interpolating a positional deviation within the image, and the interpolation means executes a weighted average process at a predetermined ratio for the color that is the basic position together with data of the same color before and after it. Device. (2) The image forming apparatus according to claim 1, wherein the ratio is a value such that MTFs of each color match at each spatial frequency.