JPH09247393A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify circuit constitution by adjusting a scanner video gain with a variable resistor. SOLUTION: A scanner 1 irradiates a document with light by using an LED array light source, photoelectrically converts its reflected light, and outputs a video analog signal. The analog video signal has its voltage divided by a resistance R and a video amplifier circuit 15 adjusts the level. The adjustment of the level is determined by the reference voltage of an A/D converter 2. The level-adjusted video signal is converted by the A/D converter 2 into a digital video signal, which is inputted to an adder 3. This adder 3, a peak level register 4, a multiplexer 5, and an arithmetic result register 6 perform shading correction, peak level correction, etc., and the video signal after the shading correction, etc., is supplied to a binarizing circuit 9 to perform MTF correction, a half-tone process, and a binarizing process, so that binary data of 0 and 1 are stored in a memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing device, and more particularly to an image processing device which can perform video level adjustment with a simple structure and with high accuracy.

[0002]

2. Description of the Related Art An image input apparatus such as a facsimile machine irradiates a read document with light from an LED array or the like and photoelectrically converts the reflected light into an analog signal. In such an optical system scanner, since the amount of light differs depending on the reading position, it is necessary to perform correction (shading correction) for it. In order to perform shading correction, first, the white reference surface is read, but if dust or the like is attached to the reading surface at that time, correct shading correction cannot be performed. Therefore, conventionally, data is stored in the RAM as an initial value, and the abnormal pixel is detected by comparing the data with the data.

[0003]

SUMMARY OF THE INVENTION The present invention, in the shading correction as described above, adjusts the scanner video gain by adjusting the volume resistor to simplify the circuit configuration and improve the accuracy of the adjustment. In the detection, the white reference data is fetched and compared with the software set value to eliminate the abnormal detection of abnormal pixels due to the movement of dust, etc., and the detection accuracy is further improved. Is set to prevent the decrease of the light amount due to the deterioration of the LED light source due to long-term use.

[0004]

According to a first aspect of the present invention, in an image processing apparatus having a shading correction function, an LCD for displaying a peak value of a video signal A / D converted when a white reference plane is read. And a display unit for displaying the peak value of the video signal on the display unit to adjust the video level with a volume resistor.

According to a second aspect of the present invention, in the first aspect of the present invention, the value of the video signal obtained by reading the white reference plane is stored in the RAM, and a scanner abnormality is displayed on a display unit such as an LCD by comparing the value with a software set value. It is characterized by being displayed.

According to a third aspect of the invention, in the first aspect of the invention, the duty of the lighting clock of the LED array used as the light source is varied to cover the reduction of the light amount due to the deterioration of the LEDs. is there.

[0007]

1 is a block diagram of an image processing circuit, and FIG. 2 is a block diagram of a control system. In the figure, reference numeral 1 is a scanner, which, as is well known, illuminates an original by an LED array light source. Is irradiated and the reflected light is photoelectrically converted to output the read video signal as an analog signal. The analog video signal is divided by the resistor R, and its level is adjusted by the video amplifier circuit 15. The level adjustment depends on the reference voltage of the A / D converter 2. For example, if the reference voltage is + 2.5V,
The variable resistor is adjusted so that the peak value of the analog video signal becomes + 2.25V, which corresponds to 90% of + 2.5V.

The level-adjusted video signal is A / D
The video signal after being converted into a digital video signal by the converter 2 and converted into a digital signal is input to the adder 3, and the adder 3 and the peak level register 4, the multiplexer 5 and the operation result register 6 perform shading correction and peak level correction. And so on. The video signal after the shading correction and the like is processed by the binarizing circuit 9 by MT.
F correction, halftone processing, and binarization processing are performed, and 0,
The binary data of 1 is stored in the memory.

FIG. 3 is a flow chart for explaining the operation of the present invention. First, the white reference plane is read by the scanner 1 (S
1). At this time, the clock for turning on the LED array light source is supplied from the facsimile engine 10 by the scanner. At the time of shipment, the duty of the clock is set to about 50%. The data read from the white reference plane is gain-adjusted by the video amplifier circuit 15 (S2), and A /
After being A / D converted by the D converter 2, it is held in the register 6 through the adder 3. At this time, the multiplexer 5
Since the output of 0 is 0, the white reference data is held in the register 6. Then, it is written in the RAM 8 by the memory I / F 7. The white reference data is 172 for A4 size.
8-bit data for 8 pixels is stored. When the white reference data is read, since 1728 peak values of the white reference data are stored in the peak level register 4, the CPU reads the value and displays the peak value on the display unit 14 in the operation unit 13. .

The data is displayed from 00h to FFh, and the variable resistor is adjusted so that the value becomes E6h which is 90% of FFh. This adjustment is usually performed in the process before shipment, but it can be adjusted after the shipment by inserting the driver into the hole for adjustment. In that case, compare the displayed value with E6h and You can easily make adjustments by displaying the turning direction on the display. Almost
After adjustment to E6h, another line white reference plane is read (S3). In this reading, abnormal pixels are detected (S4), and each time normal reading is performed, reading is performed before reading the first page. In this case as well, it is the same as the transfer route of the white reference data, and finally R
Data is stored in the AM 8 only for the read pixels. It detects if there is an abnormally low level by comparing the stored data with the software set value. When it is detected, the position of the dust or the scanner failure is displayed on the display unit to notify the operator. Remove the dust, display on the display whether to read again, and press a certain key to start reading the white reference surface again. If the same abnormality still occurs (S5), whether to start the shading correction data acquisition in this state (S5)
6) Or, when notifying the service person is displayed (S7), when the shading correction data is started to be taken in, it is displayed that there is a possibility that an image abnormality will occur at the abnormal pixel and is taken in. To start.

The shading correction data is fetched by
The one-line white reference plane is read to detect the peak value, and the detected peak value is stored in the peak level register 4. The shading correction data of each pixel is taken in by the next one-line white reference plane reading. The shading correction data is calculated by dividing the white reference data output from the A / D converter 2 by the peak level output from the peak level register 4, and the calculated data is finally stored in the RAM 8. To be done. After that, when the document is conveyed to the scan line, shading correction is performed on the shading correction data fetched earlier, correction such as peak level correction and MTF correction is performed, and the data is converted into binary data. If it is used for a long time, the LED may deteriorate and the image may become dirty due to the decrease of the light quantity. If it becomes noticeable, clean the white reference surface or the duty of the lighting clock of the LED array light source. Is increased from 50% to increase the amount of light and enhance gradation. When the duty of the LED light source lighting clock is changed, the peak level becomes the closest to the optimum value by software and the value is automatically set after the white reference plane data is taken in as in the case of the level adjustment. .

[0012]

According to the first aspect of the invention, in the image processing apparatus having the shading correction function, a display such as an LCD for displaying the peak value of the A / D converted video signal when the white reference plane is read. The video signal is adjusted by adjusting the volume resistance by displaying the peak value of the video signal on the display section, and the scanner video gain is adjusted by adjusting the volume resistance. Can be simplified and the accuracy of adjustment can be improved.

According to the invention of claim 2, in the invention of claim 1, the value of the video signal obtained by reading the white reference plane is RA.
It is characterized by displaying the scanner abnormality on the display unit such as LCD by storing it in M and comparing it with the software setting value. The white reference data is captured and compared with the software setting value to detect the abnormal pixel. Since there is no abnormal pixel undetected due to the movement of dust, the detection accuracy can be further improved.

According to the invention of claim 3, in the invention of claim 1, the duty of the lighting clock of the LED array used as the light source is varied to cover the reduction of the light amount due to the deterioration of the LED.
Since several kinds of clock duty are set to adjust the lighting clock of the array light source, LE has been used for many years.
It is possible to prevent the decrease of the light amount due to the deterioration of the D light source.

[Brief description of drawings]

FIG. 1 is a block diagram of an image processing circuit according to the present invention.

FIG. 2 is a block diagram of a control system according to the present invention.

FIG. 3 is a flowchart for explaining the operation of the present invention.

[Explanation of symbols]

1 ... Scanner, 2 ... A / D converter, 3 ... Adder, 4
... peak level register, 5 ... multiplexer, 6 ... operation result register, 7 ... memory I / F, 8 ... RAM, 9 ...
Binarization circuit, 10 ... Facsimile engine, 11 ... RO
M, 12 ... RAM, 13 ... Operation unit, 14 ... Display unit, 15
… Video amplifier circuit.

Claims (3)

[Claims] 1. An image processing apparatus having a shading correction function, comprising a display unit such as an LCD for displaying a peak value of a video signal A / D converted when a white reference plane is read, and the display unit is provided with the display unit. An image processing apparatus characterized in that the peak value of a video signal is displayed and the video level is adjusted by a volume resistor by displaying the peak value. 2. The apparatus according to claim 1, wherein the value of the video signal obtained by reading the white reference plane is stored in a RAM, and the scanner abnormality is displayed on a display unit such as an LCD by comparing it with a software set value. Image processing device. 3. The image processing apparatus according to claim 1, wherein the duty of a lighting clock of an LED array used as a light source is varied to cover a decrease in light amount due to deterioration of the LED.