JP2000224375A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct color smear of a color image signal obtained through the selection of a lighting means with a line memory of a small capacity and a computing element. SOLUTION: The image processor is provided with a light source 104 that emits repetitively a 1st luminescent color, a 2nd luminescent color, and a 3rd luminescent color whose spectral characteristics differ from each other in a 1st luminescent pattern of the luminescence in the order of the 1st luminescent color, the 2nd luminescent color, and the 3rd luminescent color, and in a 2nd luminescent pattern of the luminescence in the order of the 1st luminescent color, the 3rd luminescent color, and the 2nd luminescent color, and lights an original 101, with an image sensor 103 that obtains a pixel signal in three luminescent colors on the original 101 on the basis of a reflected light from the lighted original 101, and with a color smear correction section 105c that shifts each of bit data of each color line by one bit through addition of current line data and preceding line data of each color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus for reading a color image, and more particularly to an image processing apparatus for obtaining a color image signal by switching a lighting unit as a light source.

[0002]

2. Description of the Related Art In recent years, sheet feed scanners, flatbed scanners, handy scanners, and the like have been used as color image reading apparatuses. Here, as shown in FIG. 4, this type of device includes a light source (illuminating means) 403 that sequentially switches three colors of red (R), green (G), and blue (B) to illuminate the document 404, An image sensor 401 having one linear light receiving element array, and a lens 402 for guiding the reflected light from the original 404 to the image sensor 401 are provided. Pixel signals due to the reflected light from the original 404 corresponding to each light source 403 are sequentially transmitted. It is configured to obtain.

As described above, the linear image sensor 401
When the document 404 is read by the sheet feed scanner, the document 404 needs to be moved in a direction orthogonal to the linear image sensor 401 in synchronization with the signal output from the image sensor 401. Alternatively, in an apparatus in which the document 404 is fixed, such as a flatbed scanner, the light source 403 and the image sensor 401 need to be moved. In each device, the output result from the image sensor 401 is the same, and a color image signal corresponding to the reflected light from the document 404 is sequentially obtained.

The color image signal obtained here is shown in FIG.
As shown in (a), the light source 403 is in the lighting order, and is a time-series signal obtained by repeating R, G, and B, for example.

However, since the data is read while the original 404 or the image sensor 401 moves as described above, the output pixel signals of R, G, and B are located at locations physically separated by an amount corresponding to the reading cycle. Is the data read. The output pixel signal from the image sensor 401 is processed as data read from the same place in a subsequent signal processing unit, so that a so-called color misregistration occurs such that a color is blurred at an image boundary or the like. .

As a means for correcting the color misregistration, generally, a linear interpolation process is performed by an arithmetic process with the previous data of each color.

FIGS. 3B and 3C show output pixel signal models of each color.

In FIG. 3B, the output signals of the image sensor when reading the original 404 in the direction of the arrow are denoted by R1, G1, B1, R2, G2, B2 and R, respectively.
3, G3, B3.

Here, considering the R color, G2, B
2 should be originally read at the position of R2, but actually, a position shifted by shift 1 and shift 2 is read. Therefore,
This shift amount will be corrected.

In FIG. 3C, G is set based on R2.
2. Consider the correction of B2.

In order to correct the data of G2 to the original position R2, a correction operation is performed using the data of G1 and G2.
That is, if the document 404 is moving at a constant speed,
Since the distance between G2 and G1 about R2 is 1: 2, the equation (1) holds if the corrected data is G2 ′.

G2 ′ = (G1 + 2 × G2) / 3 (1) Similarly, correction data B2 ′ is obtained using B1 and B2.
Becomes the equation (2).

B2 ′ = (B2 + 2 × B1) / 3 (2) For the reference color R, R2 ′ = R2 (3), and it is necessary to perform this arithmetic processing for each pixel.

[0014]

However, in order to realize such a correction operation, a line memory for holding data of a previous line such as G1 and B1 and a circuit such as a multiplication and division unit are required. There is a problem that an arithmetic unit having a large scale is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image processing apparatus capable of correcting a color shift of a color image signal obtained by switching illumination means with a small-capacity line memory and a computing unit. .

[0016]

In order to solve this problem, an image processing apparatus according to the present invention provides a first luminescent color, a second luminescent color, and a third luminescent color having mutually different spectral characteristics. A first light emitting pattern that emits light in the order of a first light emitting color, a second light emitting color, and a third light emitting color, and a first light emitting color, a third light emitting color, and a second light emitting color in that order. Illuminating means for illuminating the illuminated object while repeating the second light emission pattern to emit light, and photoelectric conversion means for obtaining pixel signals of three luminescent colors in the illuminated object based on reflected light from the illuminated illuminated object And a configuration having:

This makes it possible to correct the color misregistration of the color image signal obtained by switching the illuminating means by using a small-capacity line memory and a computing unit.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a first luminescent color and a second luminescent color having mutually different spectral characteristics.
The first emission color, the second emission color, and the third emission color
A first light emitting pattern that emits light in the order of the first light emitting color and the third light emitting color, and a second light emitting pattern that emits light in the order of the first light emitting color, the third light emitting color, and the second light emitting color. An image processing apparatus having illumination means for illuminating an object to be irradiated while repeating, and photoelectric conversion means for obtaining pixel signals of three emission colors in the object to be irradiated based on reflected light from the object to be illuminated, This has the effect that the color shift correction of the color image signal obtained by switching the illumination means can be performed by a small-capacity line memory and a computing unit.

According to a second aspect of the present invention, in the first aspect, any one of the first luminescent color, the second luminescent color and the third luminescent color is red, and any other This is an image processing apparatus in which the color is green and the remaining is blue, and the color shift of the color image signal obtained by switching the illumination means can be corrected with a small-capacity line memory and an arithmetic unit. Have.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

FIG. 1 is an explanatory view showing an image processing apparatus according to an embodiment of the present invention and a configuration of a color misregistration correction unit of the image processing apparatus. FIG. 2 is an output pixel signal of the image processing apparatus shown in FIG. FIG. 3 is an explanatory diagram illustrating a positional relationship between a document and read data.

As shown in FIG. 1A, the operation of the image processing apparatus according to the present embodiment is controlled by a light source switching control unit 104a, and R, G, and R having different spectral characteristics from each other.
Original (irradiated object) 1 by sequentially switching the three color light-emitting bodies B
A light source (illuminating means) 104 for illuminating the document 101 and photoelectric conversion elements are arranged in a linear shape, and R, G,
An image sensor (photoelectric conversion unit) 103 that obtains a pixel signal of B3 color, a lens 102 that guides reflected light from the document 101 to the image sensor 103, and an image sensor 103
An image processing unit 105 that performs predetermined processing on a signal sent from the PC and outputs the processed signal to a PC (personal computer) 106.

Here, the light source 104 is an R, G, B LE
It is composed of a D chip array, R, G, B LED chips, a light guide, and the like. Also, the image sensor 103
Comprises a light receiving element such as a phototransistor or a photodiode and a shift register. The lens 102 is configured by a rod array lens, a reduction lens, or a lens array of the same magnification.

The image processing unit 105 includes the image sensor 10
An A / D converter 105 for converting the R, G, and B color pixel signals sent from 3 into analog signals and digital signals;
a, a shading correction unit 10 for correcting unevenness of illumination of the light source 104 and sensitivity variation of each pixel of the image sensor 103 with respect to each color pixel signal converted into a digital signal.
5b, a color misregistration correction unit (color misregistration correction unit) 105c that performs color misregistration correction on each color pixel signal, an MTF correction unit 105d that performs spatial frequency correction on each color pixel signal, and an output system for spectral characteristics of the image sensor 103. And a PC I / F (interface) unit 105f that outputs to the PC 106 the color pixel signals that have been subjected to such a series of corrections to the PC 106. . Note that the MTF correction unit 105
d and the color correction unit 105e may be omitted or realized by software on the PC 106.

Further, the color misregistration correction unit 105c performs addition of the current line data of each color and the previous line data, and a line memory 107 for holding the previous line data of each color necessary for performing the color misregistration correction operation. An adder 108; and a shift operation unit 1 that shifts each bit data of each color line by one bit in order to divide the addition result by the adder 108 by two.
09.

Next, correction of color misregistration in the image processing apparatus having such a configuration will be described with reference to FIGS.

In the present embodiment, the light emission order of each color of the light source 104 is not the repetition of R, G, and B as in the related art. For example, when R is used as a reference, the lighting order of G and B is switched every time. G, B, R, B, G, R, G, B. When G is used as a reference, the lighting order of R and B is switched, and when B is used as a reference, the lighting order of R and G is switched.

That is, three types of emission colors (here, R,
G, B) are the first emission color, the second emission color, and the third emission color, respectively.
, The first luminescent color, the second luminescent color, the third luminescent color, and the first luminescent pattern, the first luminescent color, the third luminescent color, and the second luminescent color. The second light emitting pattern that emits light in the order of the light emitting colors is repeated.

Therefore, as shown in FIG. 2A, the output pixel signals according to the present embodiment are R1, G1, B1, R2, B2, G2, R
3, G3, B3, R4, B4, G4.

FIGS. 2B and 2C show the reading positions of the respective colors on the original 101 when the light sources are turned on in this order.

As shown in FIG. 2B, the image sensor 10 is used to read the original 101 in the direction of the arrow.
3 is R1, G1, B1, R2, B2, G2,
R3, G3, and B3.

Here, considering the R color as a reference, G2, B2
Is originally to be read at the position of R2, but actually, a position shifted by shift 1 and shift 2 is read. Therefore, this shift amount is corrected.

As shown in FIG. 2C, the correction of G2 and B2 is considered with reference to R2. In order to correct the data of B2 to the original position R2, a correction operation is performed using the data of B1 and B2.

Assuming that the original 101 is moving at a constant speed, the distance between B2 and B1 is 1: 1 with respect to R2, so that if the corrected data is B2 ', equation (1) holds.

B 2 ′ = (B 1 + B 2) / 2 (1) Similarly, using G 1 and G 2, the correction data G 2 ′ is given by equation (2).

G2 ′ = (G2 + G1) / 2 (2) For the reference color R, R2 ′ = R2 (3)

Here, the color misregistration correction unit 105c includes a line memory 107, an adder 108, and a shift operation unit 109 as shown in FIG.

As a result, the line memory 107 holds the previous line data of each color, that is, the B1 and G1 lines, and sends them to the adder 108 together with the current lines B2 and G1 as necessary.

In the adder 108, B1, B2 and G1
And G2 are added and sent to the shift operation unit 109.

The shift operation unit 109 divides each bit data of each color line by 1 in order to divide the added result by two.
Bit shift. Therefore, there is no need to use a multiplier and a divider for dividing by 3 as in the related art.

The reference color R is output without being calculated.

The data of each color as a result of executing the operation corresponding to the above equation is converted to the MTF correction unit 105 in the next stage.
d, and thereafter, the color correction unit 105e and the PC I / F unit 1
The data is sequentially sent to the PC 106 through the network 05f.

As described above, according to the image processing apparatus of the present embodiment, the first emission pattern that emits light in the order of the first emission color, the second emission color, and the third emission color, and the first emission pattern , A third luminescent color, and a second luminescent color in this order.
Is repeated, the current line data and the previous line data of each color are added, shifted by 1 bit, and then divided by 2 to perform color shift correction. This eliminates the need for a multiplier or divider with a large circuit scale, and makes it possible to perform color misregistration correction of a color image signal obtained by switching light sources using a relatively simple small-capacity operation such as an adder and a shift operation unit. And the line memory.

[0044]

As described above, according to the present invention, the illumination is performed by the first light emission pattern and the second light emission pattern. By adding and shifting by one bit, the color shift can be corrected, and the color shift of the color image signal can be corrected by a small-capacity computing unit and a line memory.

As a result, an effective effect of increasing the calculation speed of the color misregistration correction can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an image processing apparatus according to an embodiment of the present invention and a configuration of a color misregistration correction unit of the image processing apparatus.

FIG. 2 is an explanatory diagram showing an output pixel signal by the image processing apparatus of FIG. 1 and a positional relationship between a document and read data.

FIG. 3 is an explanatory diagram showing an output pixel signal by a conventional image processing apparatus and a positional relationship between a document and read data.

FIG. 4 is an explanatory diagram showing a main part of a conventional image processing apparatus.

[Explanation of symbols]

 101 Document (illuminated object) 103 Image sensor (photoelectric conversion means) 104 Light source (illumination means) 105c Color shift correction unit (color shift correction means)

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hirofumi Kasedo 1006 Ojidoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Incorporated F term (reference) 5C072 AA01 BA19 CA05 CA07 CA12 DA21 QA12 QA17 UA12 UA13 UA18

Claims (2)

[Claims] 1. An order of a first luminescent color, a second luminescent color, and a third luminescent color with respect to a first luminescent color, a second luminescent color, and a third luminescent color having mutually different spectral characteristics. The first that emits light
, The first luminescent color, the third luminescent color, the second
Illuminating means for illuminating the illuminated object while repeating a second light emission pattern that emits light in the order of the emission colors of the three colors, and the three light emissions of the illuminated object based on the illuminated reflected light from the illuminated object An image processing apparatus comprising: photoelectric conversion means for obtaining a color pixel signal. 2. The method according to claim 1, wherein one of the first, second, and third emission colors is red, any other is green, and the other is blue. Item 2. The image processing apparatus according to Item 1.