JP2572087B2 - White balance adjustment device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a white balance adjusting device in an imaging device.

[Related Art] For example, there is known a technology for automatically adjusting white balance based on an output signal from an image sensor. For example, by controlling the amplification factors of the R signal and the B signal from the image sensor so that the integrated value of the color difference signal obtained by converting the R, G, and B signals from the image sensor approaches a predetermined reference value. Adjust the white balance.

[Problems to be Solved by the Invention] However, when such a white balance adjustment method is adopted, a certain object such as when a colored object is up or when a subject is in front of a colored wall. When the color covered most of the screen, white balance was adjusted to an unnatural color. In particular, since the deviation of the color correction in the green and cyan directions is extremely unpleasant for the human eye, it has been a very important problem to eliminate such defects in the automatic white balance adjustment technology.

Therefore, an object of the present invention is to provide a white balance adjustment device configured to always perform appropriate white balance adjustment irrespective of the situation of a subject in view of the above points.

[Means for Solving the Problems] The white balance adjustment device of the present invention includes a plurality of information holding units that hold information data indicating different white balance correction ranges, and one of the plurality of information holding units. Selecting means for selecting one according to an external instruction;
Adjusting means for adjusting the gain of each color signal component based on the information data held in the information holding means selected by the selecting means.

[Operation] According to the above-described configuration, one of a plurality of information holding units holding information data indicating mutually different white balance correction ranges is selected according to the situation at the time of shooting, and the selection is performed. This makes it possible to perform optimal white balance adjustment based on the information data held in the information holding means.

EXAMPLES Hereinafter, the present invention will be described in detail based on examples.

FIG. 1 is a block diagram showing a schematic configuration of a white balance adjusting apparatus to which the present invention is applied as one embodiment of the present invention. In this figure, 1 is an image sensor, 2 is an image sensor 1
Variable gain amplifier (hereinafter referred to as an R amplifier) for amplifying an R (red) signal from the image sensor 3, a B (blue) signal from the image sensor 1
A variable gain amplifier (hereinafter, referred to as a B amplifier) 4 for amplifying a signal, a matrix circuit 4 for producing color difference signals RY, BY and a luminance signal Y from R, G, B signals output from the imaging device; Is a clamp circuit for clamping each blanking level of the color difference signals RY and BY to the reference potential, and 7 and 8 are averaging the color difference signals RY and BY from the clamp circuits 5 and 6, respectively. 9a and 9b are A / D converters for converting the integrated outputs (RY) 'and (BY)' from the integrating circuits 7 and 8 into digital signals, and 10 is a flowchart shown in FIG. This is a microcomputer that performs a process according to the present invention, and has a ROM provided with a plurality of tables in which different white balance adjustable ranges are stored in advance. Reference numerals 11a and 11b denote D / A converters for converting digital output signals from the microcomputer 10 into gain control signals each consisting of an analog signal. The gains of the R amplifier 2 and the B amplifier 3 are controlled by gain control signals from the D / A converters 11a and 11b. Reference numeral 12 denotes a switch for selecting one of a plurality of tables in the microcomputer 10, and reference numeral 13 denotes a display device for displaying the currently used table selected by the switch 12.

FIG. 2 is a flowchart showing a control procedure to be executed by the microcomputer 10.

Next, the operation of FIG. 1 will be described with reference to the flowchart of FIG.

When the power is turned on, predetermined values V _RO and V _BO which are initial values of gain control signals V _RC and V _BC for controlling the gains of RAMP 2 and BAMP 3 are set in step S 1 (hereinafter “step” is omitted). In S2, the table in the microcomputer 10 to be used is set as the first table, and the display device 13
To indicate that it is in use.

Then, in S3, it is checked whether the switch 12 for table switching has been pressed, and if not, the process proceeds to S5,
If it is pressed, the table used in S4 is set as the next table after the currently used table, and the process proceeds to S5. In S4, if the currently used table is the last table, the process returns to the first table. The display device 13 displays which table is being used.

At S5, the initially set gain control signals V _RC and V _BC are RAMP
2, Give to BAMP3.

Then reads the reference voltage V _S at S6, the integrated output from the integrating circuits 7 and 8 in S7 (RY '), (BY ' to each input integral value V _RY, and V _BY a). In S8 to determine the magnitude relationship between the integrated value V _RY reference voltage V _S and one of the color difference signals. That is, when the integrated value V _RY is equal to or larger than the reference voltage V _S is V _RC in S10
-1 (decrease the gain control signal) as the set value V _RC ,
If it is lower than the reference voltage, in step S9, _VRC + 1 (increase the gain control signal) is set to the set value _VRC '. In then S11, it determines the magnitude relation between the integrated value V _BY reference voltage V _S and the other of the color difference signal. That is, when the integral value V _BY is equal to or higher than the reference voltage V _S
In step S13, V _BC +1 is set to the set value V _BC ', and if it is smaller than the reference voltage, in step S12, V _BC -1 is set to the set value V _BC '.

Next, in S14, it is determined whether or not the combination of the set values V _RC ′, V _BC ′ exists in the use table. In some cases, the values of the gain control signals V _RC and V _BC initially set in S15 are set to the set values V _RC ′ and V _BC ′, respectively.
It is determined whether or not the combination of V _RC ′, V _BC (initial setting value) is in the usage table. There the value of the gain control signal V _RC is being initialized in S17 and V _RC 'if, V _BC is not changed. If the combination of V _RC ′ and V _BC ′ is not in the use table in S16, it is determined in S18 whether or not the combination of V _RC (initial setting value) and V _BC ′ is in the use table. The value of the gain control signal V _BC initially set in is set to V _BC ′,
V _RC is not changed. If the combination of V _RC and V _BC ′ is not in the table used in S18, the process returns to S3 without changing both V _RC and B _BC . After the end of S15 and S17, that is, even after the values of V _RC and V _BC are determined, the process returns to S3, and the processes of S3 to S19 are repeated. Therefore, every time the switch 12 for changing the usage table is turned on and off, S3
Steps S19 to S19 are repeated, and the optimal auto white balance is always adjusted.

[Effects of the Invention] As described above, according to the present invention, optimal white balance adjustment can always be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a flowchart showing an example of the operation of the embodiment. 10 ... microcomputer, 12 ... switch.

Claims (1)

(57) [Claims] A plurality of information holding means for holding information data indicating mutually different white balance correction ranges; and a selection means for selecting one of the plurality of information holding means in response to an external instruction. Means for adjusting the gain of each color signal component based on the information data held in the information holding means selected by the selection means.