JP2612283B2 - 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] To achieve the above object, the present invention provides a memory means for storing a plurality of tables for limiting a white balance correction range, and one of the plurality of tables. And a white balance control unit that performs white balance correction within a correction range based on the table selected by the selection unit among a plurality of tables stored in the memory unit. And

[Operation] According to the present invention, one of a plurality of tables for limiting the white balance correction range in the memory means is selected based on the selection signal, and the white balance is corrected within the correction range based on the selected table. By performing the balance correction, erroneous adjustment in the white balance automatic adjustment is significantly reduced.

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 a reference voltage, and 7 and 8 average 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, respectively, and 10 is a flowchart shown in FIG. And a ROM that stores conversion information for white balance adjustment. Reference numeral 12 denotes a RAM that stores an information conversion table stored in a ROM in the microcomputer 10. The microcomputer 10 receives the RA based on the change information for changing the white balance correction range input from the input device 13.
Change the information conversion table stored in M12. 11a, 1
Reference numeral 1b denotes a D / A converter for converting a digital output signal from the microcomputer 10 into a gain control signal composed 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 14 denotes a display device that displays the value of the changed information conversion table.

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, the initial values of the gain control signals V _RC and V _BC for controlling the gains of RAMP2 and BAMP3 are set to predetermined values V _RO and V _BO in step S1 (hereinafter “step” is omitted). S2, ROM of microcomputer 10
Is stored in the RAM 12.

Then, in S3, check whether the table has been changed,
If the information for change has not been input from the input device 13, proceed to S5, and if the information for change has been input, change the information conversion table in the RAM 12 according to the change information,
The value of the current table is displayed on the display device 14, and the process proceeds to S5.

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 , V _BC initially set in S15 are set to the set values V _RC ′, V _BC ′, respectively.
It is determined whether or not the combination of _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. in the value of the initially set to have a gain control signal V _BC and V _BC ', V
_RC is not changed. If the combination of V _RC and V _BC ′ is not in the use table in S18, the process returns to S3 without changing both V _RC and V _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. Accordingly, S3 to S19 are repeated each time an instruction to change the use table is input by the input device 13, and the optimal automatic white balance adjustment is always performed.

[Effects of the Invention] As described above, according to the present invention, a memory means for storing a plurality of tables for limiting the white balance correction range is provided, and one of the plurality of tables is used as a selection signal. By providing a selection means for selecting based on the white balance correction range, it is possible to switch and select the white balance correction range, and further, within a correction range based on the table selected by the selection means among a plurality of tables stored in the memory means. By providing the white balance control means for performing the white balance correction, the erroneous adjustment in the automatic white balance adjustment can be remarkably reduced.

[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, 13 ... input device.

Claims (1)

(57) [Claims] A memory means for storing a plurality of tables for limiting a white balance correction range; a selection means for selecting one of the plurality of tables based on a selection signal; And a white balance control unit that performs white balance correction within a correction range based on the table selected by the selection unit among the plurality of stored tables.