JPH08298591A - Facsimile equipment - Google Patents

Abstract

PURPOSE: To enable a shading correction in an actual using environment even if a white reference plate to be used as the white reference at the time of reading an image is not provided all over the surface and data is not preliminarily set at the time of the shipment from a factory. CONSTITUTION: A white reference plate 9 to be used as the white reference at the time of reading an image is provided on the part of the main scanning direction of the reading of the image. Based on the image data read from the white reference plate 9 and the arithmetic expression which is preliminarily stored in a ROM 7, shading correction data is determined. Thus, the shading of a CCD sensor 1 by the shading correction data is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile machine for exchanging image data via a communication line.

[0002]

2. Description of the Related Art In a conventional facsimile apparatus, a white reference plane used as a white reference during image reading is provided on the entire surface in the main scanning direction of image reading, and image data read from the white reference plane and prestored data are stored. Based on CC
Shading correction and dark output correction of each pixel of the D sensor have been performed (see, for example, Japanese Patent Laid-Open No. 5-316299).

[0003]

However, in the conventional facsimile apparatus, a white reference surface for shading correction and dark output correction of the image reading portion such as a CCD sensor is provided on the entire surface, and a battery is mounted and shipped from the factory. Since the data necessary for shading correction and dark output correction are stored and set in the memory at some time, there is a problem that the cost of the facsimile apparatus becomes high.

In addition, when the data required for shading correction and dark output correction stored at the time of factory shipment is too different from the actual use environment, there is also a problem that shading correction and dark output correction cannot be properly performed. It was Furthermore, because the digit of the bit of the data for dark output correction is fixed, only the specific digit can be corrected, and when the dark output correction data is larger than expected, the correction does not work very well and the dark There was a problem that the output could not be corrected.

The present invention has been made in view of the above-mentioned points, and it is not necessary to provide a white reference plate to be used as a white reference at the time of image reading on the entire surface or to set data in advance at the time of factory shipment. The purpose is to enable shading correction with. It is also intended to enable accurate dark output correction in an actual use environment.

[0006]

In order to achieve the above object, the present invention provides a white reference plate used as a white reference during image reading in a part of the main scanning direction of image reading in a facsimile apparatus. A means for obtaining shading correction data is provided based on the image data read from the white reference plate and an arithmetic expression stored in advance. Further, it is preferable to provide a means for obtaining dark output correction data based on the image data read from the white reference plate and a previously stored arithmetic expression.

Further, means for reading the image data of the white original set when the power is turned on, and means for obtaining shading correction data and dark output correction data based on the read image data, and shading correction data obtained by the means. And a means for updating the shading correction data and the dark output correction data which are preset by the dark output correction data.

Further, it is preferable to provide means for detecting the peak value of the dark output correction data and means for selecting the digit of the value of the dark output correction data to be stored based on the peak value detected by the means.

[0009]

In the facsimile apparatus according to the present invention, a white reference plate used as a white reference during image reading is provided in a part of the main scanning direction of image reading, and the image data read from the white reference plate is stored in advance. Since the shading correction data is calculated based on the calculation formula, it is possible to perform shading correction during actual use without providing a white reference plate on the entire surface, and it is not necessary to set the user at factory shipment. Therefore, shading correction can be appropriately performed according to the actual use environment.

Further, if the dark output correction data is obtained based on the image data read from the white reference plate and the pre-stored arithmetic expression, the white reference plate is not required to be provided on the entire surface, and the dark output correction data can be used in actual use. The dark output correction can be performed, and since the user setting is not performed at the time of factory shipment, it is not necessary to mount a battery for that purpose, and the dark output correction can be appropriately performed according to the actual use environment.

Further, the image data of the white original set when the power is turned on is read, shading correction data and dark output correction data are obtained based on the read image data, and the obtained shading correction data and dark output are obtained. If the shading correction data and the dark output correction data set in advance by the correction data are respectively updated, the data for the shading correction and the dark output correction according to the usage environment can be set in actual use. You can

Further, if the peak value of the dark output correction data is detected and the digit of the value of the dark output correction data to be stored is selected based on the detected peak value, the range of the dark output correction can be set. Since it can be changed arbitrarily, accurate dark output correction data can be obtained according to the environment during actual use.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a facsimile apparatus according to an embodiment of the present invention. This facsimile apparatus includes a CCD sensor 1, an A / D converter 2, a dark output correction / shading correction circuit 3, an image processor 4,
Line buffer 5, CPU 6, ROM 7, and RAM 8
Consists of

A white reference plate (also referred to as "mylar") 9 used as a white reference during image reading is provided in a part of the main scanning direction of image reading, and the light source 10 is a document, a white document, and a white document. It is a light source such as an LED array that emits light when reading the image data of the reference plate 9.

The CCD sensor 1 is an optical image reading device for reading an image of a document and a white reference plate 9 for dark output correction and shading correction or an image of a white document. A / D
The conversion unit 2 is a circuit that converts the image data read by the CCD sensor 1 into digital data.

Dark output correction / shading correction circuit 3
Performs processing for obtaining dark output correction data and shading correction data of the CCD sensor 1 based on the image data read from the white document sent from the A / D conversion unit 2. Further, processing such as peak level correction and gamma (γ) correction of the CCD sensor 1 is also performed.

That is, based on the image data read from the white reference plate 9 and the processing for obtaining the dark output correction data and the shading correction data based on the arithmetic expression stored in advance in the ROM 7, and based on the image data read from the white original document. Processing for obtaining dark output correction data and shading correction data is performed.

Further, the image data of the white document set when the power is turned on is read, shading correction data and dark output correction data are obtained based on the read image data, and the obtained shading correction data and dark output are obtained. The shading correction data and the dark output correction data set in advance by the correction data are updated. Further, the peak value of the dark output correction data is detected, and the digit of the value of the dark output correction data to be stored is selected based on the detected peak value.

The image processing unit 4 performs image processing such as MTF correction and halftone correction on the image data to be transmitted by facsimile, and binarizes it. The line buffer 5 is a memory that stores image data that has been binarized by being subjected to image processing by the image processing unit 4. The image data stored here is compressed by a DCR (not shown) and is also shown. Facsimile transmission is carried out to the destination facsimile machine via the communication line by the omitted modem.

The CPU 6 controls the entire facsimile apparatus and controls the dark output correction / shading correction circuit 3 and the ROM 7 according to the present invention to obtain dark output correction data and shading correction data, and the dark output correction. It controls a dark output correction of the CCD sensor 1 based on the data and the shading correction data, and a control process for performing shading correction and other corrections.

The ROM 7 is a memory for storing various control programs of the facsimile machine and arithmetic expressions for obtaining the dark output correction data and the shading correction data according to the present invention. The RAM 8 is a working memory of the CPU 6, and stores the dark output correction data and the shading correction data obtained by the dark output correction / shading correction circuit 3.

In this facsimile apparatus, the image data output from the CCD sensor 1 is converted into digital data by the A / D converter 2 based on the control processing of the CPU 6, and the dark output correction / shading correction circuit 3 stores it in the ROM 7. The dark output correction data and the shading correction data are obtained based on the stored arithmetic expression, and they are written in the RAM 8.

Further, the dark output correction / shading correction circuit 3 obtains the dark output correction data and the shading correction data based on the image data read from the white original, and the data stored in the RAM 8 is used as the dark output correction data. Rewrite with shading correction data.

Further, the dark output correction / shading correction circuit 3 detects the peak value of the dark output correction data,
The digit of the value of the dark output correction data is selected based on the peak value, and the data of the selected digit is stored in the RAM 8 as the dark output correction data. Then, the dark output correction and the shading correction of the CCD sensor 1 are performed by the dark output correction data and the shading correction data stored in the RAM 8.

In this facsimile apparatus, when the image data of high image quality such as halftone is sent after the power is turned on, when a white original is set in advance and a predetermined button is pressed before the image of the original is transmitted, the CPU 6 causes the ROM 7 to be stored in the ROM 7. The stored command is set, the shading correction data and the dark output correction data setting mode is set, and the light source 10 is turned on to start reading the white original.

The reflected light from the white original is input to the CCD sensor 1 through a reflection glass (not shown), and C
The CD sensor 1 detects the reflected light and sends it to the A / D converter 2, and the A / D converter 2 performs direct current reproduction, AGC control, and A / D conversion, and a dark output correction / shading correction circuit 3 At, dark output correction data and shading correction data are obtained.

At this time, the dark output correction data and the shading correction data are obtained by a normal image processing algorithm. The dark output correction data and the shading correction data are stored in the RAM 8 and held until the power is turned off.

Then, after the calculation of the dark output correction data and the shading correction data is completed, the transmission operation is performed,
Dark output correction and shading correction of the CCD sensor 1 are performed based on the dark output correction data and shading correction data stored in the RAM 8, and further peak level correction and gamma correction are performed.

After that, the CCD sensor 1 reads the image of the transmission original, and the read image data is binarized by being subjected to image processing such as MTF correction and halftone processing by the image processing unit 4, which is then converted into a line. Buffer 5
After being stored in, the data is compressed by DCR and transmitted by the modem to the destination facsimile machine via the communication line.

When the white original is not set,
Alternatively, when the power is turned off and turned on again in the middle, when the document is transmitted, first, the dark output correction data and the shading correction data of a portion where the white reference plate 9 is present are obtained. That is, the image of the white reference plate 9 is read, and the dark output correction data and the shading correction data are obtained by image processing by a normal algorithm based on the image data.

After that, the dark output correction data and the shading correction data of the image data of the portion without the white reference plate 9 are obtained. When the image reading of the portion without the white reference plate 9 is started, the image data read by the white reference plate 9 and the R
The dark output correction data and the shading correction data are obtained based on the arithmetic expression stored in the OM 7 and stored in the RAM 8.

The arithmetic expression is obtained by approximating the variation of 1 of each pixel of the CCD sensor 1 by an approximate expression in advance.
The dark output correction data and the shading correction data are
It is obtained for each facsimile communication and stored in the RAM 8.

Then, when the transmission operation is performed after the calculation of the dark output correction data and the shading correction data is completed, the dark output correction and the shading correction data of the CCD sensor 1 are corrected based on the dark output correction data and the shading correction data stored in the RAM 8. Shading correction, peak level correction, and gamma correction are performed.

After that, the CCD sensor 1 reads the image of the transmission original, and the read image data is binarized by image processing such as MTF correction and halftone processing by the image processing section 4, which is then binarized. Buffer 5
After being stored in, the data is compressed by DCR and transmitted by the modem to the destination facsimile machine via the communication line.

FIG. 2 is a view showing the positional relationship among the CCD sensor 1, the white reference plate 9 and the light source 10. The white reference plate 9 is the CCD sensor 1 and the light source 10 which are the main scanning direction for reading an image.
Is provided in a part of the longitudinal direction of the. In this case, 1 to 40 pixels of the CCD sensor 1 of 120 pixels and 81 to 12 pixels
A white reference plate 9 corresponding to each of the 0 pixels is provided, and 41 to 80 pixels are a portion without the white reference plate.

First, the positions of the portion with and without the white reference plate 9 are preset in the ROM 7, and the dark output correction data and the shading correction of the portion with and without the white reference plate 9 are set based on the position data. The data calculation method is switched.

First, the shading correction data of 1 to 40 pixels and 81 to 120 pixels is (shading correction data) = (read from the white reference plate) based on the image data read from the white reference plate 9 and its peak value. Image data) / (peak value of image data read from white reference plate).

The shading correction data of 41 to 80 pixels is (shading correction data) = (based on the peak value of the image data read from the white reference plate and the value obtained by the arithmetic expression stored in the ROM 7. The value is calculated by a formula) / (peak value of image data read from the white reference plate).

For example, for the odd pixels of 41, 43, 45, ..., 79 pixels, the value based on the arithmetic expression is 5 which is the peak value.
For 0%, 42, 44, 46, ..., 80 even-numbered pixels, the following values are obtained when the value based on the arithmetic expression is 40% of the peak value. Shading correction data of odd pixels = 50/100 = 0.5 Shading correction data of even pixels = 40/100 = 0.4

In this way, the facsimile apparatus of this embodiment can perform shading correction in actual use without providing the white reference plate on the entire surface. Further, it is not necessary to perform user setting at the time of factory shipment, and it is not necessary to mount a battery for that purpose, and shading correction can be appropriately performed according to the actual use environment.

Further, the positions of the portion with the white reference plate 9 and the portion without the white reference plate 9 are stored in the ROM 7 according to the model of the facsimile apparatus, and the dark output correction of the portion with the white reference plate 9 and the portion without the white reference plate 9 is performed based on the position data. If the calculation method of the data and the shading correction data is switched, it is not necessary to detect the portion with the white reference plate 9 and the portion without the white reference plate 9, and the processing load can be reduced.

FIG. 3 is a flow chart showing a process for obtaining dark output correction data and shading correction data in the facsimile machine. In this process, when the power is turned on, it is determined in step (indicated by "S" in the figure) 1 whether or not the white original document is set and the button is pressed, and if the white original document is set and the button is not pressed, go to step 3. When the white original is set and the button is pressed, the process proceeds to step 2, where the dark output correction data and the shading correction data are obtained and stored, and the process proceeds to step 3.

In step 3, it is judged whether or not the transmission is started. If the transmission is not started, the process returns to the first process. If the transmission is started, the process proceeds to step 4 and whether the dark output correction data and the shading correction data have been stored or not. If it is already stored, the process proceeds to step 6 to perform dark output correction and shading correction of each pixel of the CCD sensor based on the already stored dark output correction data and shading correction data, read the transmission original, and read the image data. 2 is binarized and transmitted.

If the dark output correction data and the shading correction data have not been stored in the judgment in step 4,
In step 5, the dark output correction data and the shading correction data are stored, and the dark output correction data and the shading correction data are used to perform the dark output correction and the shading correction of each pixel of the CCD sensor to read the transmission original, and the image data thereof is read. 2 is binarized and transmitted.

Next, if a fixed number of bits (eg, some lower bits) of the dark correction power are stored in the RAM 8 as dark output correction data, the dynamic range cannot be obtained. For example, when the lower 3 bits of the dark output correction data are used as the dark output correction data, the dynamic range is only 8, and when the dark output correction data is larger than 8, the correction cannot be completed.

Therefore, the dark output correction data is not stored in the RAM 8 as it is, but the peak value in one line is detected and the bit number to be stored is selected based on the peak value. Therefore, the dark output correction / shading correction circuit 3 detects the peak value of the dark output data,
The digit of the value of the dark output correction data is selected based on the peak value, and the value of the digit is used as the dark output correction data in the RAM 8
To memorize.

FIG. 4 is a diagram showing an example of a circuit for selecting the digit of the dark output correction data of the dark output correction / shading correction circuit 3. This circuit includes a latch 0 circuit 11 that latches 8-bit dark output correction data by a latch signal LAT0 and a peak value (1 among the 8-bit dark output correction data latched by the latch 0 circuit 11 by a latch signal LAT1. A latch 1 circuit 12 for latching the peak value of the line) is provided.

Further, of the 8-bit dark output correction data latched in the latch 0 circuit 11 by the control signal based on the peak value in the latch 1 circuit 12, the 3-digit data (3-bit data) to be stored in the RAM 8 is selected. It also has a multiplexer 13.

For example, the peak value of the first line of the dark output correction data is "00001001", and the RAM 8 has 3 peak values.
When the bit dark output correction data is stored, the fifth to seventh bits “100” are stored, and at the time of dark output correction, the correction data “00001000” based on the data “100” is stored.
To use.

When the peak value is "00101111," the third to fifth bits "101" are stored in the RAM 8, and the correction data "00101000" based on the data "101" is used for dark output correction.

In this way, the facsimile apparatus of this embodiment can arbitrarily change the range of dark output correction, so that accurate dark output correction data can be obtained according to the environment during actual use. . Therefore, even if the dark output is large, the dark output can be accurately corrected.

[0052]

As described above, according to the facsimile apparatus of the present invention, it is not necessary to provide the white reference plate used as the white reference at the time of image reading on the entire surface or to set the data in advance at the time of factory shipment. CCD in actual use environment
Shading correction of each pixel of the sensor can be performed. Further, the dark output correction of each pixel of the CCD sensor can be accurately performed in the actual use environment. Therefore, the cost of the facsimile machine can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship among a CCD sensor 1, a white reference plate 9 and a light source 10 shown in FIG.

FIG. 3 is a flowchart showing a process for obtaining dark output correction data and shading correction data in the facsimile machine shown in FIG.

4 is a diagram showing an example of a circuit for selecting a digit of dark output correction data of a dark output correction / shading correction circuit 3 shown in FIG.

[Explanation of symbols]

 1: CCD sensor 2: A / D conversion unit 3: Dark output correction / shading correction circuit 4: Image processing unit 5: Line buffer 6: CPU 7: ROM 8: RAM 9: White reference plate (mylar) 10: Light source 11 : Latch 0 circuit 12: Latch 1 circuit 13: Multiplexer

Claims (4)

[Claims] 1. A facsimile apparatus, wherein a white reference plate used as a white reference at the time of image reading is provided in a part of the main scanning direction of image reading, and image data read from the white reference plate and previously stored calculation. A facsimile apparatus comprising means for obtaining shading correction data based on an equation. 2. The facsimile apparatus according to claim 1, further comprising means for obtaining dark output correction data based on image data read from the white reference plate and an arithmetic expression stored in advance. apparatus. 3. A facsimile apparatus, which reads image data of a white document set when a power source is turned on, obtains shading correction data and dark output correction data based on the read image data, and the means for obtaining the data. And a means for updating the shading correction data and the dark output correction data which are preset by the shading correction data and the dark output correction data, respectively. 4. The facsimile apparatus according to claim 3, wherein the means for detecting the peak value of the dark output correction data and the digit of the value of the dark output correction data to be stored based on the peak value detected by the means are selected. And a means for performing the same.