JP2895068B2 - Color image reader - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image reading apparatus, and more particularly, to a color image reading apparatus which exposes a color original using an exposure unit and uses a color image sensor to indicate the color original. And a color image reading apparatus that performs input masking correction.

[Conventional technology]

Conventionally, a color image reading apparatus using a color image sensor with a color filter is generally configured as shown in FIG. That is, a color original placed on an original platen glass 601 is illuminated by a halogen lamp (light source) 602 provided with a reflector 603, and the reflected light from the original is imaged by a lens 604 and passed through a color filter 605 to form a linear image. The light is received by the sensor 606. An image signal obtained by light source conversion by the linear image sensor 606 is amplified to a predetermined level by a video amplifier 607, and then converted to a digital image signal by an A / D (analog / digital) converter 608, and further a shading correction unit 609, masking correction unit 610, log / γ
The correction unit 611 performs various correction processes, and outputs the image data from the video interface 612 to a recording unit or a display unit (not shown) as image data. An imaging device that captures a still image or a moving image has basically the same configuration.

The conventional arrangement of the color filter and the color image sensor is generally as shown in FIGS. 7A, 7B and 7C. This figure (A) shows R
This is a case where color filters 704, 705, 706 of (red), G (green), and B (blue) and linear image sensors 701, 702, 703 for R, G, B are provided in one-to-one correspondence. FIG. 7B shows a case where a linear image sensor 707 in which pixels 708 are arranged in the same direction is arranged for a mosaic color filter 709 in which R, G, and B are alternately arranged in a line. Further, in FIG. 10C, a set of color filters 711, 712, 713 of R, G, B is configured to move in parallel in the direction indicated by the arrow in FIG. .

[Problems to be solved by the invention]

By the way, in the above color image reading device,
Since color separation is performed using a color filter, there has been a problem in that when the filter is exposed to external light and fades, the color tone (including hue and color tone) is shifted.

It is an object of the present invention to be able to easily generate input masking correction data capable of correcting a color shift with high accuracy.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a color image reading apparatus that exposes a color document using an exposure unit, generates color image data indicating the color document using a color image sensor, and performs input masking correction. A shading correction unit configured to expose a reference white plate and perform shading correction based on the obtained image data in order to correct variations between pixels in the color image sensor; and a color chart in which the shading correction is performed. Generating means for generating input masking correction data used in the input masking correction based on color chart image data obtained by exposing the color image sensor,
The generation means starts a process of creating the input masking correction data based on a user's instruction, and notifies the user of a status of the creation process and an operation to be performed by the user.

(Operation)

According to the present invention, the input masking correction data is generated based on the color chart image data on which the shading correction has been performed, and the input masking correction data generation processing is started based on a user instruction. Since the user is notified of the situation and the contents of the operation to be performed by the user, it is possible to easily generate input masking correction data capable of correcting the color shift with high accuracy.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a circuit configuration of one embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a platen glass on which a document and a color chart document for filter correction are placed; 102, a light source such as a halogen lamp for irradiating the document on the platen glass 101;
It is a reflector for collecting the light of 02 and illuminating the scanning position of the original. Reference numeral 104 denotes a lens that forms an image of the reflected light of the document, 106 denotes a color filter for color separation, and 106 denotes a linear image sensor that photoelectrically converts the document image after color separation. The color filter 106 is formed integrally with the sensor 107.

Reference numeral 105 denotes a light-shielding plate according to the present invention interposed between the lens 104 and the color filter 106. When a normal document is read, the light-shielding plate 105 covers a part of the front surface of the color filter 106 and shields light. At the time of taste correction, the light is moved to a predetermined standby position by driving the light shielding plate moving motor 117, and the color filter 106 is moved.
The function of exposing the portion which has been covered up to now is performed.

108 is a video amplifier for amplifying the output of the linear image sensor 107, and 109 is an A / D converter for digitizing the output of the video amplifier. 110 is a shading correction unit, 111
Is a masking correction unit, 112 is a log / γ correction unit, and 113
Is a video interface.

Reference numeral 114 denotes an arithmetic control unit which controls the overall arithmetic control of the apparatus, and 115
2 is a memory having a backup function for storing a control procedure (program) and control data according to the present invention as shown in FIG. Reference numeral 116 denotes a finger-touch display unit arranged on an operation panel (not shown), which is configured by pasting a touch panel made of a transparent electrode on a display screen using a CRT (cathode ray tube), liquid crystal, or the like. When a finger is placed at the specified position, data (coordinate data) is input. Reference numeral 118 denotes an operation unit for giving an instruction to the device.

In the above configuration, at the time of normal document reading,
Numeral 105 completely exposes a part of the color filter 106. When scanning of the original is started, the reflected light of the original is imaged by the lens 104, passes through the color filter 106, is separated into three colors of R, G, and B, and is received by the linear image sensor 107. And converted into an electrical image signal corresponding to the original image.

The image signal output from the linear image sensor 107 is amplified to a predetermined value by a video amplifier 108, and then converted to a video image signal by an A / D converter 109. This digital image signal is supplied to the light source 10 by the shading correction unit 110.
2. The shading of the reflector 103 and the lens 104 and the variation of the bits of the linear image sensor 107 (variation of the conversion characteristics) are corrected.

Next, after the masking correction unit 111 corrects the color difference due to the color mixture or fading of the filter 106, the logarithm
After performing the density correction by the γ correction unit 112, the image data is output from the video interface 113 to an external device (recording device or display device).

Next, the operation of the tint correction processing according to the embodiment of the present invention will be described.
This will be described in detail with reference to the flowchart of FIG. 2 and the display example of FIG. Here, the color correction means the automatic correction of the masking coefficient corresponding to the fading of the color filter 106.

First, since this correction process corrects the fading of the filter 106 due to light, it is sufficient to perform the correction process according to the number of times of use or at regular intervals. Therefore, when the color image reading apparatus is the reading section of the copying apparatus, the display of FIG. 3A is displayed on the display section 116 at every prescribed number of sheets or every prescribed time according to the number of copies (step S1). ).
Further, even when the operator intentionally wants to make the main correction by key input of the operation unit 118, the present program can be entered and the display of FIG. 3A can be displayed. If the operator does not perform the main correction, the user can press the finger to select a no display position on the display screen, and the document can be copied (step S2 → S11). When the operator wants to execute the main correction, the operator presses the display position of “Yes” on the display screen with a finger to select the position, and moves from step S2 to step S3 to enter the main correction operation.

The display of “Shading is being corrected” shown in FIG. 3 (B) is displayed on the display unit 116 (step S3), and a control signal is sent to the light shielding plate moving motor 117, and the light shielding plate 105 is moved by the motor 117. Then, light is also applied to the unexposed portion of the color filter 106 (step S4). Subsequently, based on image data of light reflected from a reference white plate provided on a document cover (not shown), the light amount of the light source 102 and the video amplifier 108 are determined.
After fine-tuning with the amplification factor, the shading correction unit 110 samples the shading correction data to make it ready for shading correction (step S
Five).

Next, a message "Please place the filter correction chart at a predetermined position" is displayed on the display unit 116 as shown in FIG. 3 (C) (step S6), and several seconds after this display, FIG. 3 (D) Is displayed to prompt the operator to place the correction color chart at a predetermined position on the platen glass 101 (step S7). When it is confirmed that the chart has been placed by pressing the yes finger on the display screen (step S8), the chart is displayed on the display unit 116 with "Under correction" shown in FIG. 3 (F) (step S9). The sampling and correction of the correction data are performed in the order described in (1).

First, the process proceeds to step S10, and the masking coefficient at the time of correction shipment stored in the memory 115 is changed to the masking correction unit 11.
1 and a color chart for filter correction as shown in FIG.
Read from 7.

Here, assuming that the characteristic of the color filter 106 faded by light is as shown by the broken line curve in FIG. 5, the filter portion which is always used for reading the original image and has the bleached filter portion and the unexposed filter portion for correction. In the output between sensors, a level difference of color data occurs.

That is, since the image data of the unexposed portion has not faded, image data of a predetermined level which is known in advance,
Rk, Gk and Bk are obtained. On the other hand, in the filter part which is actually always used (hereinafter, referred to as the actual use part), Rd, Gd, and Bd having different colors are obtained for the respective color charts.

The following equation (1) shows a masking correction equation used in this embodiment.

Where Ro, Go, Bo are the data after masking correction, R _I , G _I , B _I are the masking input data, Rr, Rg, Rb, Gr, Gg, Gb, Br, Bg, Bb are the masking coefficients .

Therefore, first, the red (red) portion of the filter correction color chart is read by the image sensor 107 by sampling, and the ratios Δr, Δg, and Δb of the image data of the unexposed portion and the image data of the actually used portion are obtained.

Next, the process proceeds to step S11, where the masking coefficient is corrected based on the calculation results of the above equations (2) to (4). When the new masking coefficients are Rrn, Rgn, and Rbn, respectively, they are given by the following equations (5), (6), and (7).

A new masking coefficient for Red is obtained by the operations of the above equations (5) to (7). The same applies to Green
(Green) and Blue (blue) filter color charts are read, and new masking coefficients Grn, Ggn, Gbn, Brn, Bgn, Bbn corrected for Gr, Gg, Gb, Br, Bg, Bb are obtained. The masking coefficient of the masking correction unit 111 is updated.

After the correction (correction) of the masking coefficient is completed, the new masking coefficient is compared with a predetermined value to determine whether or not the correction is within the correction range. A message "Please replace the sensor" is displayed on the display unit 116 to inform the operator that a defect has occurred in the sensors 106 and 107.

Also, if the new masking factor is within the correction range,
Proceeding to step S12, "copy is possible" shown in FIG. 3 (F) is displayed on the display unit 116 to inform the operator that the correction operation of the filter correction has been completed.

After the above operation is completed, the control signal is sent to reverse the light shielding plate moving motor 117 to move the light shielding plate 105,
Thus, a predetermined portion of the color filter 106 is exposed. Thereby, all the correction operations according to the present invention are completed.

As a result, not only the effect of light fading of the filter due to light can be automatically corrected, but also a small-capacity memory can be used, and correction corresponding to color fluctuation of the correction chart can be performed.

In the above-described embodiment of the present invention, a document reading apparatus used in a copying machine, a facsimile apparatus, or the like is illustrated as the color image reading apparatus. However, the present invention is not limited to this. It goes without saying that the same correction as in the present embodiment can be performed for a color correction machine of a video camera. In this case, a color filter for correction is attached on the imaging lens instead of the correction chart, and the uniform correction is performed. Correction can also be performed by transferring an image of a different color.

Although the movable light shielding plate 105 is used to shield a part of the color filter in the embodiment shown in FIG. 1, the present invention is not limited to this. The same effect can be obtained by using an image sensor longer than (length), opening the window only for the length of the actual use part and mounting the image sensor, and moving the image sensor in the main scanning direction only at the time of correction according to the present invention. Is obtained. In the case where the color filter has a structure as shown in FIGS. 7A and 7C, a portion which is not exposed to light is formed on the color filter by using a color filter longer than the image sensor. The same effect can be obtained by moving the filter along the direction of the image sensor at the time of correction according to.

〔The invention's effect〕

As described above, according to the present invention, the input masking correction data is generated based on the color chart image data on which the shading correction has been performed, and the process of generating the input masking correction data is started based on a user instruction. Since the user is notified of the status of the creation process and the content of the operation to be performed by the user, it is possible to easily generate input masking correction data capable of correcting a color shift with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of an embodiment of the present invention, FIG. 2 is a flowchart showing a control operation of the embodiment of the present invention in FIG. 1, and FIGS. FIG. 4 is a plan view showing an example of a display screen displayed during the operation of FIG. 4, FIG. 4 is a plan view showing an example of a color chart for filter correction used in the embodiment of the present invention, and FIG. FIG. 6 is a characteristic diagram showing an example of the difference in terms of the relationship between wavelength and output, FIG. 6 is a block diagram showing a circuit configuration of a conventional example, and FIGS. It is a schematic diagram which shows an arrangement configuration. 104: lens, 105: light shielding plate, 106: color filter, 107: image sensor, 110: shading correction unit, 111: masking correction unit, 112: log / γ correction unit, 114: calculation Control unit, 115: memory, 116: display unit, 117: motor for moving the light shielding plate, 118: operation unit.

Claims (2)

(57) [Claims] 1. A color image reading apparatus for exposing a color document using exposure means, generating color image data indicating the color document using a color image sensor, and performing input masking correction, A shading correction unit for exposing a reference white plate and performing shading correction based on the obtained image data in order to correct a variation between pixels in the sensor; and exposing a color chart on which the shading correction has been performed and exposing the color image. Generating means for generating input masking correction data to be used in the input masking correction based on the color chart image data obtained by the sensor, wherein the generating means starts the process of generating the input masking correction data based on a user's instruction And inform the user of the status of the creation process and the contents of the operation to be performed by the user. Color image reading apparatus characterized by knowledge. 2. The color image reading apparatus according to claim 1, wherein the content of the operation to be performed by the user is to place the color chart at a predetermined position.