JPH01143592A - White balance correction system - Google Patents

Abstract

PURPOSE:To facilitate the adjustment of white balance by providing in adjusting memory respectively corresponding to each of two output signals in 3 kinds of output signals from a color image sensor. CONSTITUTION:R, G, B output signals from a color image CCD sensor 10 are converted respectively into digital signals by A/D converters 21-23 and set to registers 31-33. A multiplexer 41 outputs a value of the register 31 not in the adjustment mode and outputs a signal on an address bus of a device control circuit 70 in case of the adjustment mode. A multiplexer 42 applies similar operation. Outputs of the multiplexers 41, 42 are given to an address terminal of E<2> PROM 51, 52. The output of the E<2> PROM 51, 52 is set to registers 61, 62. The device control circuit 70 in case of white balance adjustment allows the sensor 10 to read a gray scale and writes a data in the adjustment memories 51, 52 so that the corrected contrast of an R signal and the corrected contrast of the corrected G signal are respectively equal to the contrast of the B signal.

Description

[Detailed Description of the Invention] [Summary] Regarding a white balance correction method for a color image sensor, the present invention provides a high-fidelity, simple, and inexpensive white balance correction method for a color image sensor. Two of the three types of output signals (R, G, B) output from the color image sensor
Two adjustment memories are provided for each of the output signals (for example, R signal and G signal), and the color image
The R signal and G signal output from the sensor are input as addresses to the corresponding adjustment memories, and successive data from the adjustment memories are used as corrected color signals.

When performing white balance adjustment, the color image sensor reads the gray scale, and the corrected R
Data is written into the adjustment memory corresponding to the R signal and the adjustment memory corresponding to the G signal so that the gray value of the signal and the corrected gray value of the G signal are respectively equal to the gray value of the B signal.

[Industrial application field]

The present invention relates to a white balance correction method for a color image sensor.

(Prior Art) Conventional white balance circuits perform adjustment using analog circuits.

[Problem that the invention seeks to solve]

In conventional technology, color image sensor R (red)
, G (green), and B (blue) outputs and the output linearity from low to high concentrations are corrected by adjusting the analog circuit. There are problems such as aging.

The present invention was created in view of this point, and it is an object of the present invention to provide a high-fidelity, simple, and inexpensive white balance correction method for color image sensors.

[Means for solving problems]

FIG. 1 is a diagram showing the principle of the present invention. The color image sensor 10 has a first analog output signal, a second analog output signal, and a third analog output signal (R, G, B).
Output. The first analog signal is converted into a digital signal by the A/D converter 21, and this digital signal is set in the register 31. Similar processing is performed on the second analog signal and the third analog signal. The device control circuit 70 includes a processor 71 and a control memory 7.
It has 2. The output of the register 31 is input to one input terminal of the multiplexer 41, and the signal on the address bus of the device control circuit 70 is input to the other input terminal. The multiplexer 41 selects one of the two input signals and inputs the selected signal to the address terminal of the adjustment memory 51. The output of the register 32 is input to one input terminal of the multiplexer 42, and the signal on the address bus of the device control circuit 70 is input to the other input terminal. The multiplexer 42 selects one of the two input signals and inputs the selected signal to the address terminal of the adjustment memory 52. The outputs of register 31, register 32 and register 33 are selectively connected to the data bus of device control circuit 70 by connection means 91. The data terminals of the adjustment memory 51 and the adjustment memory 52 are selectively connected to the data bus of the device control circuit 70 by connection means 92 . Adjustment mode setting switch 80 is connected to the data bus of device control circuit 70 via a gate.

〔Example〕

FIG. 2 is a bronch diagram of one embodiment of the present invention.

In the figure, 10 is a color CCD sensor, 21 to 23 are A/D converters, 31 to 33 are registers, and 41
and 42 are multiplexers, and 51 and 52 are E” PROMs.
, 61 and 62 are registers, 70 is a device control circuit, 71 is a microprocessor, 72 is a control ROM, 80 is an adjustment mode setting switch, and 91 and 92 are connection means, respectively. FIG. 2 shows a portion of a color image scanner device.

The color CCD sensor 10 is a contact type color CCD.
Sensors can be used. FIG. 4(a) shows a side sectional view of the contact type color CCD sensor, and FIG. 4(Φ) shows a plan view. In the figure, 1 indicates a red lens, 2 a green lens, 3 a blue lens, and 4 a CCD cell. A red lens 1 is provided above the first cell 4, a green lens 2 is provided above the second cell 4, and a blue lens 3 is provided above the third cell 4. is provided. The following is as shown.

As the color CCD sensor 10, a color CCD line・
Of course it is also possible to use sensors.

The R output signal of the color CCD sensor 10 is sent to the A/D converter 2.
1 is converted into a digital signal and set in the register 31, and the G output signal of the color CCD sensor 10 is A.
It is converted into a digital signal by the /D converter 22 and set in the register 32, and the B of the color CCD sensor 10 is
The output signal is converted into a digital signal by the A/D converter 23 and set in the register 33. Multiplexer 41 outputs the value of register 31 when not in adjustment mode, and outputs the signal on the address bus of device control circuit 70 when in adjustment mode.

Multiplexer 42 also performs similar operations. The output of multiplexer 41 is input to the address terminal of E'' PROM51, and the output of multiplexer 42 is input to E'' PROM5.
It is input to the address terminal of No.2.

EzPROM is called non-volatile RAM.

The output of E" PROM51 is set to register 61, and the output of EZ PROM52 is set to register 62. Device control circuit 70 controls E2PROM51 and
Data can be written to 2. Device control circuit 70
has a microprocessor 71 and a control ROM 72. The adjustment mode setting switch 80 is used to set whether or not the adjustment mode is set, and when the adjustment mode setting switch 80 is closed, the adjustment mode is set. Connection means 91
consists of tristate gates. The same applies to the connecting means 92.

FIG. 5 is a diagram showing an example of characteristics of a color CCD sensor.

Assuming that the gradation value is 16 gradations from 0 to F, mixing red light with a gradation value of F, green light with a gradation value of F, and blue light with a gradation value of F results in pure white. If you mix red light with a gradation value of O, green light with a gradation value of 0, and blue light with a gradation value of O, you will get pitch black. When you mix red light with a gradation value of 8, green light with a gradation value of 8, and blue light with a gradation value of 8, you get gray. When gray is read by a color CCD sensor, it is desirable that the value of the red output signal, the value of the green output signal, and the value of the blue output signal be equal, but in reality, the value of the red output signal, as shown in Figure 5, The value of the green output signal and the value of the blue output signal are not equal.

FIG. 6 is a diagram showing an example of gray scale.

Gray scale is paper that has multiple areas of gray of different shades. However, pure black is the darkest gray, and pure white is the lightest gray. The gray gradation is, for example, 10 gradations.

FIG. 3 is a diagram showing the processing of the device control circuit 70. When adjusting the white balance, gray scale is used as the reading paper, and the mode is set to adjustment mode.

■ Check whether it is in adjustment mode. When the answer is YES, the process (■) is performed.

■ Determine whether the color image scanner device is activated. In the case of YES, the process of (2) is performed.

■ Set the motor rotation position to N. Initially, the color CCD sensor 10 is made to read a completely black area on a gray scale.

■ Read the R output value ■ of the color CCD sensor 10.

(2) Read the G output value vG of the color CCD sensor 10.

(2) Read the G output value v8 of the color CCD sensor 10.

(E” Write data V to address vR of PROM 51.

■ Write data ■8 to EX PROM5217) address ■6.

■ Check whether it is finished or not. If NO, N+α is set to N in order to read the next gray area, and the process returns to (2).

When not in adjustment mode, R of color CCD sensor 10
Data is read from the E'' PROM 51 using the output as an address, and the read data is set in the register 61.

Similarly, data is read from the E'' PROM 52 using the G output of the color CCD sensor 10 as an address, and subsequent data is set in the register 62.The B output of the color CCD sensor 10 is set in the register 63 as is.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, (a) white balance adjustment is very easy;

(b) Optimal white balance for each device can be achieved.

(C) The balance can be adjusted by the user (adjustment mode setting is open).

It is possible to achieve remarkable effects such as:

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is a diagram showing the processing of the device control circuit 70, and FIG. 4 is an overview of the contact type color CCD sensor. diagram showing,
FIG. 5 is a diagram showing an example of characteristics of a color CCD sensor, and FIG. 6 is a diagram showing an example of a color scale. 1...Red lens, 2...Green lens, 3...
・Blue lens, 4... COD cell, 10... Color CCD sensor, 21 to 23... A/D converter, 3 to 33... Register, 41 and 42... Multiplexer, 51 and 52...E” PROM, 61
and 62... register, 70... device control circuit, 71
... Microprocessor, 72 ... Control ROM, 8
0...Adjustment mode setting switch.

Claims (1)

[Claims] A color image sensor (10); and a first image sensor output from the color image sensor (10).
a first A/D converter (21) that converts the analog output signal of the color image sensor (10) into a digital signal;
a second A/D converter (22) that converts the analog output signal of the color image sensor (10) into a digital signal;
a third A/D converter (23) that converts the analog output signal of
register (31), and a second A/D converter (22) in which the output of the second A/D converter (22) is set.
register (32) and a third A/D converter (23) in which the output of the third A/D converter (23) is set.
a register (33); a device control circuit (70) having a processor (71) and a control memory (72); a first adjustment memory (51); a second adjustment memory (52); 1 register (31) output and device control circuit (70)
a first multiplexer (41) that selects one of the signals on the address bus and inputs the selected signal to the address terminal of the first adjustment memory (51); and a second register. (32) output and device control circuit (70)
a second multiplexer (42) for selecting one of the signals on the address bus and inputting the selected signal to the address terminal of the second adjustment memory (52); and a first register. (31) output, the second register (32
) and the output of the third register (33) to a data bus of the device control circuit (70); and a first adjustment memory (51). a second connection means (92) for selectively connecting the data terminal and the data terminal of the second adjustment memory (52) to the data bus of the device control circuit (70); and an adjustment mode setting switch (80). A white balance correction method characterized by comprising: