JPH01112887A - White balance adjusting device - Google Patents

Abstract

PURPOSE:To eliminate the influence of the object color of a white balance adjustment by providing plural input devices on a white balance automatic adjusting device. CONSTITUTION:A microcomputer 11 reads in a (R-Y)BP and a (B-Y)BP by an A/D converter 10 as soon as the peak detecting signal of a peak detecting circuit becomes 1. A color difference signal level at the time of the blanking of a vertical synchronizing signal is read in by a synchronizing signal VDX of a vertical synchronizing signal V. Based on these data, the microcomputer 11 judges whether it is a light source color or not, selects data, controls the gains of an R signal amplifier 2 and a B signal amplifier 3 based on the selected data. Thus, the white balance adjustment is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a white balance adjustment device that automatically adjusts white balance in a color imaging device.

[Prior Art] Conventionally, as a method of automatically performing white balance adjustment of a color imaging device using only signals from an image sensor or an image pickup tube, there is a method as described in Japanese Patent Application Laid-Open No. 101188/1983. Then, based on the peak level of the RGB signal output from the image pickup tube or image sensor and the value obtained by integrating the RGB signal over one field period, adjust the amplifier gain of each RGB signal so that the peak level of the RGB signal becomes the same level. is controlled, and when the difference in values obtained by integrating the RGB signals over one field period exceeds a certain level, a correction signal is added to the gain control based only on the peak level.

Figures 7(a) and 7(b) show scenes in which conventional white balance adjustment devices based on signals from image sensors or image pickup tubes are weak. This figure shows a case where the color of a highly saturated object dominates, and the figure (b) shows a case where the peak part has a color far different from that of the light source.

In Figure 7(a), even if the peak level of the RGB signal is white, the saturation level of the value integrated over one field period of the RGB signal is extremely high, so only the peak level of the color of the highly saturated object is present. A gain control correction signal is added based on .

Further, in FIG. 7(b), when the white balance is adjusted based on the RGB peak signal values, red is corrected to white, and the white background becomes blue. Here, even if the value integrated over one field period of the RGB signal exceeds a certain level and a correction signal is output, natural white balance adjustment cannot be performed.

[Problems to be solved by the invention] As mentioned above, in the conventional white balance adjustment device,
The gain of the amplifier for each RGB signal is controlled so that the peak values of the RGB signals output from the image pickup tube or image sensor are at the same level, and thereby the RGB signal is integrated over one field period or at a constant level. In order to operate in such a way that it does not exceed

For example, when the saturation level of the value obtained by integrating the RGB signal over one field period is extremely high, there is a problem in that it is affected by the saturation level. Furthermore, if the peak part of the scene has a color with a high saturation level that is far from the light source, if you adjust the white balance based on the peak value of the RGB signal, in this case, the color with a high saturation level will be corrected to white. There was a problem that the white background turned blue.

This invention was made to solve this problem.If the color of a high-brightness part of one screen or the color of a value obtained by dividing RGB signals for one field period has an extremely high saturation, that color will be affected by the light source. Judging that it is an object color that is far from color,
It is an object of the present invention to provide a white balance adjustment device that eliminates the influence of this object color.

[Means for Solving the Problems] In order to achieve the above object, the white balance adjustment device of the present invention adjusts the amplifier of each color signal using signals of high luminance and low chroma portions within the screen. It is equipped with means for controlling gain.

[Function] By having the above-mentioned configuration, for example, when an image is captured of a color far different from the light source color, white balance adjustment can be performed to eliminate the influence of the object color.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the white balance adjustment device of the present invention, and FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. It is a flow chart of a microcomputer in an example.

In FIG. 1, l is an image sensor, 2 is an R signal amplifier for controlling the R gain from RGB signals, and 3 is an R signal amplifier for controlling the R gain from RGB signals.
4 is also a B signal amplifier, and 4 is a luminance signal Y and a color difference signal RY from RGB signals.

7 is a peak detection circuit that detects the peak time of the luminance signal Y; 5.6 is the peak detection circuit that detects the color difference signals R-Y and B-Y and the vertical synchronization signal V, respectively.
synchronization signal V. Sample hold (sample at timing X and hold the level until the next sampling)
9 is an integration circuit that integrates the color difference signal B-Y for one field period; 10 is a color difference signal R-Y, B (R-Y)I and (B-Y) which are the outputs of the -Y integration circuit 8.9
(R-
Y) BP, (B-Y) A/D converter for converting BP from an analog signal to a digital signal; 11 reads data based on the signal digitized by this A/D converter IO; 9 judges data selection; A microcomputer 12.13 performs processing such as gain control, and is an A/D converter that converts a digital signal output from the microcomputer 11 into an analog signal.

In the configuration shown in FIG. 1, an image captured by the image sensor 1 is converted into RGB electrical signals. Of the RGB signals, the R signal and the B signal are each sent to the R signal amplifier 2. B
The signal is amplified by the signal amplifier 3. These R signal amplifiers 2. By changing the gain of B signal amplifier 3, RG
Controls the balance of the B signal. Next, that RG
The matrix circuit 4 generates a luminance signal Y and color difference signals R-Y, B-Y based on the B signal, and whether a signal processing circuit is further provided on the output side is irrelevant to the present invention. The specific configuration and explanation thereof will be omitted. Based on the color difference signals R-Y and B-Y created by the matrix circuit 4, the dividing circuits 8 and 9 divide the color difference signals R-Y)I into one field period.

(B-Y)I is created. Further, in the S/H circuit 5.6, (R-Y
)BP, (B-Y)BP are made, (RY)I, (B
-Y)I, (RY)BP, and (B-Y)BP signals are converted into digital signals by the A/D converter 10, and the microcomputer 11 reads these signals.

When the peak detection circuit 7 of the luminance signal Y detects a peak value, the S/H circuits 5 and 6 detect the color difference signals R-Y, B-Y at that time.
Hold and output the value. At the same time, the peak detection signal is also sent to the microcomputer 11, and the microcomputer 11 reads (R-Y)BP and (B-Y)BP by the A/D converter lO at the same time that the peak detection signal of the peak detection circuit becomes 1. . After the S/H circuit 5.6 detects the peak of the luminance signal Y,
Even if it takes a little time for the microcomputer 11 to read the color difference signals R-Y and B-Y, the purpose is to read accurate values. Also, using a procedure similar to peak detection,
The color difference signal level during blanking of the vertical synchronizing signal V is also read by the synchronizing signal vDx of the vertical synchronizing signal V.

Based on these data, the microcomputer 11 determines whether it is the light source color, selects the data, and controls the gains of the R signal amplifier 2 and the B signal amplifier 3 based on the selected data.

Note that the analog signal output from the microcomputer 11 is digitized by D/A converters 12 and 13, and then sent to an R signal amplifier 2. Input to B signal amplifier 3.

FIG. 2 is a flowchart showing the entire process of the microcomputer II.

When the power is turned on in step (1), in step (2), preset gain control voltage initial values R and B of the R signal amplifier and B signal amplifier are output. In step (3), counter C in microcomputer 11 is set to O, and in step (4), l is added to counter C. In step (5), the operation is divided into four operations depending on the number of counter C at that time.

First, in step (6), the blanking level of the color difference signals R-Y and B-Y and the integral value of one field period of the color difference signals R-Y and B-Y are input, and in step (7) is the color difference signal R of the high luminance part of the luminance signal Y in one field.
-Y, B-Y are input, step (8) is data selection, step (9) is R gain,
An operation is performed to output the B gain, and step (37) is an operation to set the counter C to 0. When the operations from step (6) to step (9) are completed, this process is repeated again.

As is clear from the above explanation, after the electric raON, the R
Outputs the initial values R and B of the gain and B gain, and outputs the color difference signal R.
-Y, B-Y blanking level, color difference signal R-Y,
By repeating the input of the integrated value of B-Y for one field period, the R-Y and B-Y input of the high luminance part of the luminance signal Y in one field, the selection of data, and the output of R gain and B gain, White balance adjustment is performed using feedback control.

FIG. 3 is a flowchart showing the operation of step (6) in FIG. 2 in more detail. Step (10)
is the integral value of the color difference signals R-Y and B-Y (R-Y)1
．． (B-Y)I is input, step (11) waits for the timing of the synchronization signal VCIX of the vertical synchronization signal V, and when this synchronization signal vDx is input, the process moves to step (I2). Then, in step (12), the blanking levels of the color difference signals R-Y and B-Y are input to (R-Y)B and (B-Y)B. Step (13) returns, and when the operations from step (6) to step (12) are completed, the process returns to step (6).

FIG. 4 is a flowchart showing in detail the operation of step (7) in FIG.

In step (14), the synchronization signal V. Wait for the timing when X changes from l to 0, set the counter Q = 0 in step (15), and judge whether P, which is the output of the peak detection circuit 7, is l or O in step (16), and if l, step To (17),
If O, go to step (18). Step (17) is (
Brush the value of (RY)BP to (RY)P and also (B
-Y)P plus the value of (B-Y)BP, and (B
-Y) To P (B-Y) Add 1 to the value of BP to the counter Q. Synchronization signal V in step (18). The operations in steps (16) to (18) are repeated until X becomes l again. Step (19)
-Y) BP.

Calculate the average of (B-Y)BP and (R-Y)P.

(B-Y) Input to P. Step (20) returns and returns to step (7) when the operations from step (7) to step (19) are completed.

By the above operation, the average value (B-Y)P of the color difference signals of the high brightness portion of the brightness signal Y in the 1 field is obtained.

Input (RY)P into memory.

FIG. 5 is a flowchart showing in detail the operation of the stem (8) in FIG.

In step (21), it is determined whether or not the peak detection circuit 7 has detected a peak during the l field period. If there is no peak value, the process goes to step (23), and if there is a peak value, the process goes to step (22). Step (22) is the brightness signal Y
It is determined whether the color saturation in the color difference signal of the high luminance part is larger or smaller than a preset threshold value P, and if it is larger, the process goes to step (23), and if it is smaller, the process goes to step (24).

Further, in steps (23) and (24), it is determined whether the color saturation in the value obtained by integrating the color difference signal in one field is larger or smaller than a preset threshold value (■). If it is larger, go to step (26) in case of step (23), and go to step (2) in case of step (24).
If it is smaller, go to step (25) if it is step (23), and go to step (28) if it is step (24).
). Step (25) is the precision value (R-
It operates to input Y)I and (B-Y)I as data to (RY) data and (B-Y) data. Step (
26) is an operation to return the counter C to O. Step (
27) is the color difference signal (RY) of the high brightness part of the brightness signal Y
P, (B-Y) P as data, (R-Y) data, (
b-y) This is the operation of inputting data. -Step (2
8) is the color difference signal (RY) P of the high brightness part of the brightness signal Y.
, (B-Y)P and the integral value of the color difference signal (R-Y)I, (B
-Y) This is an operation of inputting the two average values of I as data to (RY) data and (B-Y) data, step (29) is a return, and step (8) to step (
When the operations up to 28) are completed, the process returns to step (8).

To summarize the above operation, when the peak detection circuit 7 does not detect a peak value during the l field and the saturation of the integral value of one color difference signal is smaller than the preset threshold value I, the integral value of the color difference signal Perform white balance adjustment based on.

When the peak detection circuit 7 does not detect a peak value during the l field and the saturation of the fine value of the color difference signal is larger than a preset threshold value ■, the output R gain and B gain are not changed.

When the saturation of the color difference signal in the high brightness part of the screen is greater than the preset threshold value P and the saturation of the integral value of the color difference signal is less than the threshold value I, white is set based on the integral value of the color difference signal.・Perform balance adjustment.

The saturation of the color difference signal in the high brightness part of the screen is the threshold value P
When the saturation of the integral value of the color difference signal is larger than the threshold value ■, the output R gain and B gain are not changed.

The saturation of the color difference signal in the high brightness part of the screen is the threshold value P
When the saturation of the fine value of the color difference signal is smaller than the threshold value I, white balance adjustment is performed based on the color difference signal of the high brightness portion of the screen.

Furthermore, when the saturation of the color difference signal in the high brightness part of one screen is less than the threshold value P and the saturation of the integral value of the color difference signal is less than the threshold value I, the color difference signal in the high brightness part of the screen and the integral value of the color difference signal are White balance adjustment is performed based on the average value of .

As described above, data is selected by determining whether the input signal is a color that can be considered as a light source color or is clearly due to an object color.

FIG. 6 is a flowchart showing the operation of step (9) in FIG. 2 in detail. Step (30) is (RY)
Data or color difference signal R-Y blanking level (R-Y
) B is larger or smaller than B, and if it is smaller, the R gain is increased by I LSB in step (31). If it is larger, the R gain is lowered by step (32). In step (33), the (B-Y) data is the color difference signal B.
-Y blanking level (B-Y) It is determined whether it is larger or smaller than B. If it is smaller, the B gain is increased by L Llill in step (35). Also, if it is large, step (
34) lowers the B gain to ILSR. Step (36
) is a return, and when the operations from step (9) to step (35) are completed, the process returns to step (9).

In addition to the embodiments described above, the present invention is also effective in a white balance adjustment circuit having a plurality of color difference signal data detection devices.

In addition, in the above embodiment, the saturation is determined by setting a certain threshold level, but there is also a method in which combinations of hue and saturation that are considered as light source colors are stored in a table in the microcomputer memory. In this case, there is also a method in which a flicker detection device for fluorescent lamps or something similar is provided to determine whether or not the lamp is a fluorescent lamp to further limit this table.

[Effects of the Invention] As explained in detail above, the present invention eliminates the influence of object color on white balance adjustment, which is a problem in the conventional art, by providing a plurality of input devices in an automatic white balance adjustment device. It is something that can be done.

This is particularly effective for automatic white balance adjustment devices based on signals from image sensors or image pickup tubes that are greatly affected by object color, and is useful when the color of a highly saturated object occupies most of the screen or when the peak part of an image , when the color is far different from the light source, you can adjust the natural white balance.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the white balance adjustment device of the present invention, Fig. 2 is a flowchart showing the overall processing of the microcomputer, and Fig. 3 is the operation of step (6) in Fig. 2. 4 is a flowchart showing in detail the operation of step (7) in FIG. 2, FIG. 5 is a flowchart showing in detail the operation of step (8) in FIG. 2, FIG. 6 is a flowchart showing the operation of step (9) in FIG. It is a diagram showing scenes in which he is good at. In the figure. 1: Image sensor 2: R signal amplifier 3: B signal amplifier 4: Matrix circuit 5.5: S/
H circuit 7: Peak detection circuit 8.9 = Integrating circuit 10
: A/D converter 11: Microcomputer 12.13: D/A converter Representative Patent attorney 1) Haru Kitatake Figure 3 Figure 4 Figure 6 Figure 7

Claims (1)

[Claims] A white balance adjustment device comprising means for controlling the gain of an amplifier for each color signal using signals of high luminance and low chroma portions within a screen.