JP2002281343A - Black level correcting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a black level correcting device with high versatility, by which abrupt change of black level between the respective images are prevented and various black level compensating operations are selected without increasing the circuit scale. SOLUTION: Black level reference data is updated from the average value of the black levels per frame or line and black level reference data at the previous time, a black level of a valid image data is corrected by using the black level reference data after update.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a black level correction device for correcting a black level of image data captured by an image sensor.

[0002]

2. Description of the Related Art In a semiconductor device, charges are accumulated with the passage of time even in a state where light is blocked. The charge accumulated in this way regardless of light is called dark current. In order to electrically correct and remove this dark current, a light-shielding portion is provided in a part of the sensor photosensitive portion, a reference value of the dark current is detected, and this reference value is clamped and the amount of change from this is detected. A method of obtaining only a signal component is generally used.

FIG. 23 is a block diagram showing a conventional black level correction apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 64-18370. In FIG. 23, reference numeral 1 denotes an image data imaged by an image sensor from analog data to digital data. A / D converter for converting to data, 2 for a gate, 3 for a memory for storing black level reference data corresponding to each pixel of the image sensor, 4 for A
The subtracter subtracts black level reference data from the image data converted into digital data by the / D converter 1 to correct the black level of the image data.

Next, the operation will be described. Black level reference data corresponding to each pixel of the image sensor is stored in the memory 3 in advance. When the A / D converter 1 converts image data captured by the image sensor from analog data to digital data, The black level reference data corresponding to the pixel is output to the subtractor 4.

A subtractor 4 subtracts black level reference data from the image data converted into digital data by the A / D converter 1 to correct the black level of the image data. Thereby, it is possible to eliminate the variation in the black level of each pixel.

[0006]

Since the conventional black level correction device is configured as described above, it is possible to eliminate the variation in the black level of each pixel. However, for example, in a case where image data is continuously obtained as in a digital still camera, the black level between the images may change suddenly, but there is a problem that the sudden change cannot be prevented. . In addition, there is a problem that the black level correction method is always the same, and the versatility of the black level correction device cannot be improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a black level correction device capable of preventing a sharp change in black level between images. It is another object of the present invention to provide a highly versatile black level correction device capable of selecting various black level correction operations without increasing the circuit scale.

[0008]

A black level correction apparatus according to the present invention updates the black level reference data from the average value calculated by the average value calculation means and the previous black level reference data, and updates the updated black level reference data. The black level of the image data is corrected using the level reference data.

A black level correction device according to the present invention calculates an average value of black level data per line.

[0010] A black level correction apparatus according to the present invention calculates an average value of black level data per frame.

The black level correction apparatus according to the present invention calculates an average value of black level data per line, calculates an average value of black level data per frame, and calculates one of the average values. Is selected and output to the updating means.

The black level correction device according to the present invention multiplies the previous black level reference data by the first weighting value, while multiplying the average value calculated by the average value calculating means by the second weighting value smaller than the first weighting value. , And the results of the multiplication are added to each other to obtain new black level reference data.

A black level correction device according to the present invention calculates an average value of black level data belonging to a first region in an optical black region, and calculates a black value belonging to a second region in the optical black region. The average value of the level data is calculated.

The black level correction apparatus according to the present invention selects the one of the average values calculated by the average value calculation means or the black level reference data updated by the update means and outputs the selected data to the correction means. A selection means is provided.

The black level correcting device according to the present invention includes a second selecting means for selecting the fixed value stored in the fixed value storing means or the black level reference data updated by the updating means and outputting the same to the correcting means. It is provided.

The black level correcting apparatus according to the present invention includes a third selecting means for selecting the initial value stored in the initial value storing means or the black level reference data updated by the updating means and outputting the selected data to the correcting means. It is provided.

A black level correction device according to the present invention sets a horizontal pixel number in an optical black region, sets a shift count of a shift operation, and sets the number of horizontal pixels by the horizontal pixel number set by the setting circuit. An arithmetic circuit for integrating the black level data and performing a shift operation on the integration result by the number of shifts corresponds to an average value calculating means.

A black level correcting apparatus according to the present invention sets a number of vertical lines in an optical black region, sets a shift number of shift operations, and sets the number of vertical lines by the number of vertical lines set by the setting circuit. An arithmetic circuit for integrating the average value of the black level line and performing a shift operation on the integration result by the number of shifts corresponds to an average value calculating means.

In the black level correcting apparatus according to the present invention, the average value calculating means includes a plurality of setting circuits, and the arithmetic circuit selects one of the setting circuits.

The black level correcting device according to the present invention is provided with a connecting means for outputting image data picked up by the image pickup device to the average value calculating means and the correcting means only when correcting the black level. .

The black level correction device according to the present invention outputs the corrected image data when the correction start permission signal is significant, and outputs the image data before correction when the correction start permission signal is insignificant. It is something to do.

According to the black level correcting apparatus of the present invention, the specified value is subtracted from the updated black level reference data by the updating means, and the subtraction result is subtracted from the image data.

The black level correction device according to the present invention subtracts the specified value from the black level reference data when the updated black level reference data is larger than the specified value by the updating means, and calculates the subtraction result from the image data. If the black level reference data is not larger than the designated value, the black level reference data is subtracted from the image data.

The black level correcting device according to the present invention corrects the dynamic range after correcting the black level of the image data.

According to the black level correcting apparatus of the present invention, the black level reference data updated based on the average value of the black level data belonging to the first area in the optical black area, and the black level reference data in the optical black area. The average value with the updated black level reference data based on the average value of the black level data belonging to the second area is calculated.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a black level correction device according to Embodiment 1 of the present invention.
Denotes a lens system that forms an optical image of the subject, 12 denotes an image sensor that photoelectrically converts the subject image formed by the lens system 11 and outputs image data that is an electric signal, and 13 denotes an image sensor that is output from the image sensor 12. An analog processing unit 14 performs analog processing such as amplifying image data, and an A / D converter 14 converts the image data output from the analog processing unit 13 from analog data to digital data.

15 clips the data belonging to the black level clip area in the optical black area from the image data output from the A / D converter 14 and performs the integration of the horizontal black level. By dividing by the number of pixels, 1
A line black level calculation circuit 16 for calculating the average value of the black level per line is integrated in the vertical direction with the average value of the black level per line calculated by the line black level calculation circuit 15 and then divided by the number of lines. , A frame black level calculation circuit 17 for calculating the average value of the black level per frame, and outputs the black level reference data calculated by the time constant calculation circuit 18 to the A terminal of the time constant calculation circuit 18. A time constant data selection circuit for selecting an average value of the black levels calculated by the line black level calculation circuit 15 or the frame black level calculation circuit 16 and outputting the average value to the B terminal of the time constant calculation circuit 18. The line black level calculation circuit 15, frame black level calculation circuit 16 and time constant data selection circuit 17 constitute an average value calculation means.

Numeral 18 multiplies the previous black level reference data input from the terminal A by a first weighting value, and multiplies the average value of the black level input from the terminal B by a second weighting value smaller than the first weighting value. And a time constant calculating circuit (updating means) for obtaining new black level reference data by adding the results of both multiplications to each other. A time constant calculating circuit 19 uses the black level reference data calculated by the time constant calculating circuit 18 to generate A. The correction circuit (correction unit) corrects the black level of the image data output from the / D converter 14. FIG. 2 is an explanatory diagram showing a sensor surface of the imaging device 12 such as a CCD, and FIG. 3 is an explanatory diagram showing a selection result of the time constant data selection circuit 17.

Next, the operation will be described. The sensor surface is
It is mainly divided into an effective pixel area and an optical black area (see FIG. 2). The optical black area is an area where a light-shielding portion is provided on the sensor photosensitive portion and a dark current reference value is detected. In the first embodiment, 32 pixels × 10
It is assumed that a dark current reference value in a black level clip region of 24 lines is detected.

First, of the black level correction operation, the frame propagation black level correction operation of detecting the black level of one frame and subtracting the detection result from the effective image data of the next frame will be described.

First, when the lens system 11 forms a subject image, the image sensor 12 photoelectrically converts the subject image and outputs image data as an electric signal, and the analog processing unit 13 amplifies the image data. Perform analog processing. The A / D converter 14 converts the image data output from the analog processing unit 13 from analog data to digital data, and outputs the digital data to the line black level calculation circuit 15 and the correction circuit 19.

When receiving the digital image data from the A / D converter 14, the line black level calculation circuit 15 clips data belonging to the black level clip region in the optical black region from the image data. Then, when the scanning of “A”, which is the first line of the black level clip area, is started after the start of shooting, the line black level calculation circuit 15 integrates the black level of 32 pixels, and outputs the integration result as one line. By dividing by “32” which is the number of pixels per minute, the average value of the black level per line is calculated. Hereinafter, this operation is performed up to 1024 lines in the order of “A” and “U”.

The frame black level calculating circuit 16 integrates the average value of the black level per line calculated by the line black level calculating circuit 15 by 1024 lines in the vertical direction. Then, the integration result is expressed as “10” which is the number of lines.
By dividing by 24 ″, the average value of the black level per frame is calculated.

Next, the time constant data selection circuit 17 calculates a1
The terminal receives the previous black level reference data calculated by the time constant calculating circuit 18 from the terminal, inputs the average value of the black level per frame calculated by the frame black level calculating circuit 16 from the b1 terminal, and inputs from the c1 terminal The average value of the black level per line calculated by the line black level calculation circuit 15 is input.

In the frame propagation black level correction operation, as shown in FIG. 3, the previous black level reference data input from the terminal a1 is output to the terminal A of the time constant calculation circuit 18, and one frame input from the terminal b1 is output. The average value of the hit black level is output to the B terminal of the time constant calculation circuit 18.

The time-constant calculation circuit 18 controls the A as follows to prevent a sharp change in the black level between the images.
The previous black level reference data input from the terminal is multiplied by the first weight value (= 63/64), while the average value of the black level per frame input from the B terminal is changed by the second weight value (= 1). / 64), and the results of both multiplications are added to each other to obtain new black level reference data. C = A × 63/64 + B / 64 where A: previous black level reference data input from terminal A B: average black level per frame C: new black level reference data

When the photographing of the next frame is started, the correction circuit 19 clips the effective image data of the effective pixel area from the image data output from the A / D converter 14. Then, from the effective image data, the time constant calculation circuit 1
The black level reference data calculated in step 8 is subtracted to correct the black level of the effective image data. The line black level calculation circuit 15 and the frame black level calculation circuit 1
6, time constant data selection circuit 17 and time constant calculation circuit 18
Performs the same operation in the next frame as in the previous frame.

Next, among the black level correction operations, an in-plane black level correction operation of detecting the black level of one line and subtracting the detection result from the effective image data of the next line will be described.

The operations of the lens system 11, the image pickup device 12, the analog processing section 13, the A / D converter 14, the line black level calculation circuit 15, and the frame black level calculation circuit 16 are the same as the above-described frame propagation black level correction operation. Therefore, the description is omitted.

The time constant data selection circuit 17 receives the previous black level reference data calculated by the time constant calculation circuit 18 from the terminal a1 and inputs the per-frame per frame calculated by the frame black level calculation circuit 16 from the terminal b1. The average value of the black level is input, and the average value of the black level per line calculated by the line black level calculation circuit 15 is input from the terminal c1.

In the in-plane black level correction operation, as shown in FIG. 3, the previous black level reference data input from the a1 terminal is output to the A terminal of the time constant calculation circuit 18, and one line input from the c1 terminal is output. The average value of the hit black level is output to the B terminal of the time constant calculation circuit 18.

The time-constant operation circuit 18 controls the A as described below in order to prevent a sharp change in the black level between the images.
The previous black level reference data input from the terminal is multiplied by the first weight value (= 63/64), while the average value of the black level per line input from the B terminal is changed by the second weight value (= 1). / 64), and the results of both multiplications are added to each other to obtain new black level reference data. C = A × 63/64 + B / 64 where A: previous black level reference data input from terminal A B: average black level per line C: new black level reference data

When the scanning of the first line of the effective pixel area starts, the correction circuit 19 clips the effective image data of the first line from the image data output from the A / D converter 14. Then, the black level reference data (“A”) calculated from the effective image data by the time constant calculation circuit 18.
, The black level of the effective image data is corrected.

When the scanning of the second line of the effective pixel area starts, the black level reference data for the line "A" is subtracted from the effective image data of the second line to change the black level of the effective image data. to correct. Black level correction is similarly performed for the effective image data of the third and subsequent lines.

As is clear from the above, the first embodiment
According to the method, the black level reference data is updated from the average value of the black level per frame or line and the previous black level reference data, and the black level of the effective image data is updated using the updated black level reference data. Since the correction is made, it is possible to prevent a sharp change in the black level between the images. Also, a line black level calculation circuit 1
5, since the frame black level calculation circuit 16 and the time constant data selection circuit 17 are provided, the frame propagation black level correction operation and the in-plane black level correction operation can be performed without increasing the circuit scale. As a result, there is an effect that a highly versatile black level correction device can be obtained.

Although the black level clip area is 32 pixels × 1024 lines in the first embodiment, the black level clip area may be arbitrary, and accordingly, the line black level calculation circuit 15 and the frame black level calculation circuit 16
May be changed.

In the first embodiment, the equation for giving the time constant is shown as C = A × 63/64 + B / 64. However, the present invention is not limited to this, and the equation may be changed as necessary. do it. The operation and processing of the time constant operation circuit 18 according to the first embodiment can also be realized by a microprocessor.

Embodiment 2 FIG. 4 is a block diagram showing a black level correcting apparatus according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. Reference numeral 15a clips data belonging to a black level clip region (first region) in the optical black region from the image data output from the A / D converter 14, and performs integration of the horizontal black level. After that, a line black level calculation circuit for calculating the average value of the black level per line by performing division by the number of pixels, and 15b is an optical black area from the image data output from the A / D converter 14. After clipping the data belonging to the black level clip area (second area) within, the black level in the horizontal direction is integrated and then divided by the number of pixels, the average value of the black level per line is obtained. This is a line black level calculation circuit to be calculated.

16a is obtained by integrating the average value of the black level per line calculated by the line black level calculation circuit 15a in the vertical direction, and then dividing by the number of lines.
A frame black level calculation circuit for calculating an average value of black levels per frame;
This is a frame black level calculation circuit that calculates the average value of the black level per frame by integrating the average value of the black level per line calculated by b in the vertical direction and then dividing by the number of lines.

Reference numeral 20 denotes an average value of the average value of the black level per frame calculated by the frame black level calculation circuit 16a and the average value of the black level per frame calculated by the frame black level calculation circuit 16b. The frame black level averaging circuit 21 outputs the black level reference data calculated by the time constant calculating circuit 18 to the A terminal of the time constant calculating circuit 18 while the line black level calculating circuit 15 outputs the black level reference data.
b, a time constant data selection circuit that selects the average value of the black levels calculated by the frame black level calculation circuit 16a or the frame black level averaging circuit 20 and outputs the selected value to the B terminal of the time constant calculation circuit 18. The line black level calculation circuits 15a and 15b and the frame black level calculation circuits 16a and 1
6b, a frame black level averaging circuit 20 and a time constant data selecting circuit 21 constitute an average value calculating means. FIG. 5 is an explanatory diagram showing a sensor surface of the image pickup device 12 such as a CCD, and FIG. 6 is an explanatory diagram showing a selection result of the time constant data selection circuit 21.

Next, the operation will be described. The sensor surface is
It is mainly divided into an effective pixel area and an optical black area (see FIG. 5). The optical black area is an area where a light-shielding portion is provided on the sensor photosensitive portion and a dark current reference value is detected. In the second embodiment, 1600 pixels ×
A three-line black level clip area (first area);
Black level clip area of 2 pixels × 1024 lines (second
Area) is detected.

First, of the black level correction operation, the frame propagation black level correction operation of detecting the black level of one frame and subtracting the detection result from the effective image data of the next frame will be described.

First, when the lens system 11 forms a subject image, the image sensor 12 photoelectrically converts the subject image and outputs image data as an electric signal, and the analog processing unit 13 amplifies the image data. Perform analog processing. Then, the A / D converter 14 converts the image data output from the analog processing unit 13 from analog data to digital data, and outputs the digital data to the line black level calculation circuits 15a and 15b and the correction circuit 19.

The line black level calculation circuit 15a integrates the black level of 1600 pixels when the scanning of "A" which is the first line of the black level clip area (first area) is started after the photographing is started. The average of the black level per line is calculated by dividing the integration result by "1600" which is the number of pixels for one line. Hereinafter, this operation is performed up to three lines in the order of “a” and “c”.

The line black level calculation circuit 15b
When scanning of “d”, which is the first line of the black level clip region (second region), is started, the black level of 32 pixels is integrated, and the integration result is expressed as “32” which is the number of pixels for one line. To calculate the average value of the black level per line. Hereinafter, this operation is referred to as "O",
The processing is performed up to 1024 lines in the order of “f”.

The frame black level calculation circuit 16a integrates the average value of the black level per line calculated by the line black level calculation circuit 15a for three lines in the vertical direction. Then, the average of the black level per frame in the first area is calculated by dividing the integration result by the number of lines “3”.

The frame black level calculation circuit 16b
Is 1 calculated by the line black level calculation circuit 15b.
The average value of the black level per line is integrated for 1024 lines in the vertical direction. Then, the average value of the black level per frame in the second area is calculated by dividing the integration result by the number of lines “1024”.

The frame black level averaging circuit 20 calculates the average value of the black level per frame in the first area and the second black level.
The average value of the black levels of the first area and the second area is obtained by adding the average value of the black level per frame in the area and dividing the addition result by “2”.

Next, the time constant data selection circuit 21 sets a2
The terminal receives the previous black level reference data calculated by the time constant calculating circuit 18 from the terminal, the average value of the black level per frame calculated by the frame black level calculating circuit 16a from the terminal b2, and the terminal c2 from the terminal c2. The average value of the black level per line calculated by the line black level calculation circuit 15b is input, and the average of the black levels of the first area and the second area calculated by the frame black level averaging circuit 20 from the terminal d2. Enter a value.

In the frame propagation black level correction operation, as shown in FIG. 6, the previous black level reference data input from the terminal a2 is output to the terminal A of the time constant calculation circuit 18 and the first black level reference data input from the terminal d2 is input. The average value of the black level in the area and the second area is output to the B terminal of the time constant calculation circuit 18.

The time-constant calculation circuit 18 controls the A as follows to prevent a sharp change in the black level between the images.
The previous black level reference data input from the terminal is multiplied by the first weighting value (= 63/64), while the average of the black levels of the first and second areas input from the B terminal is converted to the second value. , And the results of both multiplications are added to each other to obtain new black level reference data. C = A × 63/64 + B / 64 where A: previous black level reference data input from terminal A B: average value of black levels of first and second areas C: new black level reference data

When the photographing of the next frame is started, the correction circuit 19 clips the effective image data of the effective pixel area from the image data output from the A / D converter 14. Then, from the effective image data, the time constant calculation circuit 1
The black level reference data calculated in step 8 is subtracted to correct the black level of the effective image data. The line black level calculating circuits 15a and 15b, the frame black level calculating circuits 16a and 16b, and the frame black level averaging circuit 2
0, time constant data selection circuit 21 and time constant calculation circuit 18
Performs the same operation in the next frame as in the previous frame.

Next, the in-plane black level correction operation of detecting the black level of one line and subtracting the detection result from the effective image data of the next line in the black level correction operation will be described.

The lens system 11, the image sensor 12, the analog processing section 13, the A / D converter 14, the line black level calculation circuits 15a and 15b, and the frame black level calculation circuits 16a and 1
6b and the operation of the frame black level averaging circuit 20 are the same as the above-described frame propagation black level correction operation, and therefore description thereof is omitted.

The time constant data selection circuit 21 receives the previous black level reference data calculated by the time constant calculation circuit 18 from the terminal a2, and receives the data per frame calculated by the frame black level calculation circuit 16a from the terminal b2. The average value of the black level is input, the average value of the black level per line calculated by the line black level calculation circuit 15b is input from the terminal c2, and the first value calculated by the frame black level average circuit 20 from the terminal d2. The average value of the black levels of the area and the second area is input.

In the in-plane black level correction operation, when the black level of the first area is detected, the previous black level reference data input from the terminal a2 is supplied to the A terminal of the time constant calculating circuit 18 as shown in FIG. Then, the average value of the black level per frame input from the terminal b2 is output to the terminal B of the time constant calculation circuit 18. In the in-plane black level correction operation,
When detecting the black level of the second area, as shown in FIG.
The previous black level reference data input from the two terminals is output to the A terminal of the time constant calculation circuit 18, and the average value of the black level per line input from the c2 terminal is calculated by the time constant calculation circuit 18.
To the B terminal.

The time constant calculation circuit 18 controls the A as follows to prevent a sharp change in the black level between the images.
The previous black level reference data input from the terminal is multiplied by the first weight value (= 63/64), while the average of the black level per frame or line input from the B terminal is converted to the second weight value. (= 1/64), and the results of both multiplications are added to each other to obtain new black level reference data. C = A × 63/64 + B / 64 where A: last black level reference data input from terminal A B: average value of black level per frame or line C: new black level reference data

When the scanning of the first line of the effective pixel area starts, the correction circuit 19 clips the effective image data of the first line from the image data output from the A / D converter 14. Then, the black level reference data (black level reference data up to the line of “A, I, C”, which is the first area) calculated by the time constant calculation circuit 18 is subtracted from the effective image data. Correct the black level of the image data.

When the scanning of the second line of the effective pixel area starts, the effective image data of the second line is clipped from the image data output from the A / D converter 14.
Then, the black level reference data (black level reference data up to the line “D”, which is the second area) calculated by the time constant calculation circuit 18 is subtracted from the effective image data, and the black of the effective image data is subtracted. Correct the level. In addition,
For the effective image data of the third and subsequent lines, black level correction is performed in the same manner as the effective image data of the second line.

As is apparent from the above, the second embodiment
According to the method, the average value of the black level data belonging to the first area in the optical black area is calculated, and the average value of the black level data belonging to the second area in the optical black area is calculated. With such a configuration, it is possible to select various black level correction operations with one circuit and realize highly accurate black level detection. As a result, there is an effect that a more versatile black level correction device can be obtained.

In the second embodiment, the first region is 1600 pixels × 3 lines, and the second region is 32 pixels × 1024 lines. However, the black level clip region may be arbitrarily set. The divisors of the line black level calculation circuits 15a and 15b and the frame black level calculation circuits 16a and 16b may be changed accordingly.

Embodiment 3 FIG. 7 is a block diagram showing a black level correcting apparatus according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIG. 22 is a frame black level calculation circuit 1
A selection circuit (first selection means) that selects the average value of the black level per frame calculated by 6a or the black level reference data calculated by the time constant calculation circuit 18 and outputs the selected data to the correction circuit 19. FIG. 8 is an explanatory diagram showing selection results of the time constant data selection circuit 21 and the selection circuit 22.

Next, the operation will be described. In the frame propagation black level correction operation and the in-plane black level correction operation, the selection circuit 22 always selects the black level reference data input from the v terminal and outputs it to the correction circuit 19. For this reason, the same control as in the second embodiment is performed.

However, in the in-plane black level correction operation, the independent in-plane black level correction operation for performing independent black level correction for each frame without transmitting black level data between frames is as follows.

First, at the time of detection of the first area, the selection circuit 22 selects the average value of the black level of the first area input from the u terminal and outputs it to the correction circuit 19. On this occasion,
The time constant data selection circuit 21 compares the average value of the black level of the first area inputted from the terminal b2 with
The average value of the black level per line input from the terminal c2 is output to the terminal B of the time constant calculation circuit 18. At this stage, the processing of the line black level calculation circuit 15b is not performed. Therefore, the time constant calculation is not performed.

Next, when the scanning of the first line of the effective pixel area starts, the correction circuit 19 subtracts the average value of the black level of the first area selected by the selection circuit 22 from the effective image data, and The black level of the line is corrected. Next, when the scanning reaches the black level clip line "D" in the second area, the line black level calculation circuit 15b integrates the black levels of the 32 pixels "D", and the average value is used as the time constant data selection circuit 21. Output to

At this time, the first signal already input to the A terminal
The average value of the black level in the region and the average value of the black level of "D" input to the B terminal via the c2 terminal are calculated by the time constant calculating circuit 18, and the calculation result is obtained by the C terminal. Are output to the time constant data selection circuit 21 and the selection circuit 22.

Next, when the black level detection of "D" in the second area is completed, the selecting means 22 selects and corrects the black level reference data which is the calculation result of the time constant calculation circuit 18 inputted from the v terminal. Output to the circuit 19.

Next, when the scanning of the second line of the image effective area starts, the correction circuit 19 subtracts the operation result of the time constant operation circuit 18 selected by the selection circuit 22 from the effective image data, and Perform eye black level correction. Or later,
By performing the same control as in the second line, the final 102
Black level correction is performed for each line up to four lines. By repeating the above control for each frame, an independent in-plane black level correction operation for performing independent black level correction for each frame without transmitting black level data between frames becomes possible.

As is clear from the above, the third embodiment
The selection circuit 22 selects the average value of the black level per frame calculated by the frame black level calculation circuit 16a or the black level reference data calculated by the time constant calculation circuit 18 and outputs the selected data to the correction circuit 19. Provided, one circuit can select various black level correction operations,
It is possible to realize highly accurate black level detection.
As a result, there is an effect that a more versatile black level correction device can be obtained.

Embodiment 4 FIG. 9 is a block diagram showing a black level correcting apparatus according to Embodiment 4 of the present invention. In the figure, the same reference numerals as those in FIG. 23, a black level fixed value storage unit (fixed value storage unit) for storing a desired black level fixed value;
Is a selection circuit (second selection means) that selects a fixed value stored in the black level fixed value storage unit 23 or an output value of the selection circuit 22 and outputs the selected value to the correction circuit 19. FIG. 10 is an explanatory diagram showing selection results of the time constant data selection circuit 21 and the selection circuits 22 and 24.

Next, the operation will be described. In the frame propagation black level correction operation, the in-plane black level correction operation, and the independent in-plane black level correction operation, the selection circuit 24 always selects the output value of the selection circuit 22 input from the x terminal and outputs it to the correction circuit 19. . Therefore, the control is the same as in the third embodiment.

On the other hand, the case where the black level correction is performed with a preset black level fixed value without performing the black level detection operation is as follows.

In the fixed value black level correction operation, the selection circuit 24 selects the black level fixed value input from the w terminal and outputs it to the correction circuit 19. Next, when the scanning of the first line of the image effective area starts, the correction circuit 19 performs the black level correction of the first line by subtracting the black level fixed value selected by the selection circuit 24 from the effective image data. .

Thereafter, by performing the same control as that for the first line, black level correction is performed for each line up to the last 1024 lines. By repeating the above control, it is possible to perform a fixed value black level correction operation for performing black level correction with a preset black level fixed value without performing a black level detection operation.

As is apparent from the above, the fourth embodiment
According to the first embodiment, the selection circuit 24 for selecting the fixed value stored in the black level fixed value storage unit 23 or the output value of the selection circuit 22 and outputting the selected value to the correction circuit 19 is provided. By selecting the level correction operation, it is possible to realize highly accurate black level detection. As a result, there is an effect that a more versatile black level correction device can be obtained.

In the black level fixed value storage unit 23 in the fourth embodiment, a desired fixed value of the black level is set in advance, but if it is replaced with a microprocessor, an arbitrary value can be set. Is possible, and versatility can be further improved.

Embodiment 5 FIG. 11 is a configuration diagram showing a black level correction device according to Embodiment 5 of the present invention. In the figure, the same reference numerals as those in FIG. 9 denote the same or corresponding parts, and a description thereof will be omitted. Reference numeral 25 denotes a black level initial value storage unit (initial value storage unit) for storing a desired black level initial value;
Reference numeral 6 denotes a selection circuit (third selection means) that selects the initial value stored in the black level initial value storage unit 25 or the black level reference value data calculated by the time constant calculation circuit 18 and outputs it to the selection circuit 22. It is. FIG. 12 is an explanatory diagram showing selection results of the time constant data selection circuit 21 and the selection circuits 22, 24, and 26.

Next, the operation will be described. Selection circuit 26
When selecting the black level reference value data input from the y terminal, the description is omitted because it is the same as in the fourth embodiment. However, during the black level correction of the first frame in the frame propagation black level correction operation and the black level correction of the first line in the in-plane black level correction operation, the selection circuit 26 selects the initial value input from the z terminal. . In this case, the selection circuit 22 selects data at the v terminal, and the selection circuit 24 selects data at the x terminal.

When the selection circuit 26 selects the initial value input from the z terminal, the correction circuit 19 subtracts the initial value from the effective image data and performs the black level correction of the first frame or the first line. The black level correction for the first frame or the first and subsequent lines is performed in the same manner as in the fourth embodiment.

As is clear from the above, the fifth embodiment
According to the present invention, the selection circuit 26 is provided for selecting the initial value stored in the black level initial value storage unit 25 or the black level reference value data calculated by the time constant calculation circuit 18 and outputting it to the selection circuit 22. It is possible to select various black level correction operations with one circuit and realize highly accurate black level detection. As a result, there is an effect that a more versatile black level correction device can be obtained.

Although the desired black level initial value is set in advance in the black level initial value storage unit 25 in the fifth embodiment, an arbitrary initial value can be set by replacing it with a microprocessor. And the versatility can be further improved.

Embodiment 6 FIG. FIG. 13 is a configuration diagram showing the insides of the line black level calculation circuit 15 and the frame black level calculation circuit 16 of the black level correction device according to the sixth embodiment of the present invention. A divisor reference circuit (setting circuit) 32 for setting the number of horizontal pixels and for setting the number of shifts of the shift operation circuit 33. The divisor reference circuit 32 outputs black level data per line by the number of horizontal pixels output from the divisor reference circuit 31. A black level integration circuit 33 for integrating is a shift operation circuit for shifting the integration result of the black level integration circuit 32 by the number of shifts. Note that an operation circuit is configured by the black level integration circuit 32 and the shift operation circuit 33.

Reference numeral 34 denotes a divisor reference circuit (setting circuit) for setting the number of vertical lines of the optical black area to be clipped and the number of shifts of the shift operation circuit 36. Reference numeral 35 denotes a vertical line output from the divisor reference circuit 34. A black level integration circuit for integrating the average value of the black level line by several minutes, 36
Is a shift operation circuit that shifts the integration result of the black level integration circuit 35 by the number of shifts. Note that an arithmetic circuit is configured by the black level integration circuit 35 and the shift arithmetic circuit 36.

Next, the operation will be described. In the first embodiment and the like, the internal configurations of the line black level calculation circuit 15 and the frame black level calculation circuit 16 are not particularly mentioned, but may be configured as shown in FIG.

For example, as shown in FIG.
The effective pixel area and the optical black area are roughly classified, and when 32 pixels × 512 lines are set as the black level clip area in the optical black area, as shown in FIG. 15, refer to the divisor of the line black level calculation circuit 15. A set value H′5 (the number of clipped pixels “32”, the number of shifts “5”) is set in the circuit 31.
The set value H′9 (the number of clip lines “512”, the number of shifts “9”) is set in the divisor reference circuit 34 of the frame black level calculation circuit 16.

The black level integration circuit 32 of the line black level calculation circuit 15 integrates black level data per line by the number of horizontal pixels output from the divisor reference circuit 31. That is, when the set value H'5 is set in the divisor reference circuit 31, the black level data of 32 pixels is integrated. The shift operation circuit 33 of the line black level calculation circuit 15 shifts the integration result of the black level integration circuit 32 by the number of shifts. That is, the set value H′5 is the divisor reference circuit 3
When set to 1, the integration result of the black level integration circuit 32 is shifted by 5 bits.

Thus, the line black level calculation circuit 15
In the shift operation circuit 33, the average value of the black level data per line is calculated, and the average value is calculated by the c of the frame black level calculation circuit 16 and the time constant data selection circuit 17.
Output to one terminal. As described above, when the processing of the line “A” is completed, the processing of “A” and “U” is performed in the following order.
Similar processing is performed up to 12 lines.

When the black level integration circuit 35 of the frame black level calculation circuit 16 receives the average value of the black level data per line from the line black level calculation circuit 15, the number of vertical lines output from the divisor reference circuit 34 The line average value of the black level is integrated by the minute (the data of the black level per frame is integrated). That is, when the set value H'9 is set in the divisor reference circuit 34, the line average value of the black level for 512 lines is integrated.

The shift operation circuit 36 of the frame black level calculation circuit 16 shifts the integration result of the black level integration circuit 35 by the number of shifts. That is, the set value H'9
Is set in the divisor reference circuit 34, the integration result of the black level integration circuit 32 is shifted by 9 bits. Thus, the shift operation circuit 36 of the frame black level calculation circuit 16 calculates the average value of the black level data per frame, and outputs the average value to the b1 terminal of the time constant data selection circuit 17.

The subsequent steps are the same as those in the first embodiment and the like, and will not be described. As is clear from the above, according to the sixth embodiment, the frame propagation black level correction operation and the in-plane black level correction operation can be realized by one circuit, and the divisor reference circuits 31, 34 and By providing the shift operation circuits 33 and 36, a more versatile black level correction device can be provided without increasing the circuit scale.

[0102] In the sixth embodiment, although the black level clipping region with 32 pixels × 512 lines, black level clipping region may be a respective horizontal / vertical 2 ^n,
The values set in the divisor reference circuits 31 and 34 may be changed accordingly.

Embodiment 7 FIG. FIG. 16 is a configuration diagram showing the insides of the line black level calculation circuit 15 and the frame black level calculation circuit 16 of the black level correction device according to the seventh embodiment of the present invention. The description is omitted because the portion is shown. 31a is a divisor reference circuit (setting circuit) similar to the divisor reference circuit 31 used in mode 1, 31b is a divisor reference circuit (setting circuit) similar to the divisor reference circuit 31 used in mode 2, and 41 is a divisor reference circuit 31a. Alternatively, a pixel number selection circuit for selecting the number of horizontal pixels set by the divisor reference circuit 31b, and a shift number selection circuit for selecting the number of shifts set by the divisor reference circuit 31a or the divisor reference circuit 31b.

Reference numeral 34a denotes a divisor reference circuit (setting circuit) similar to the divisor reference circuit 34 used in mode 1, 34b denotes a divisor reference circuit (setting circuit) similar to the divisor reference circuit 34 used in mode 2, and 43 denotes a divisor. A line number selection circuit 44 selects the number of vertical lines set by the reference circuit 34a or the divisor reference circuit 34b, and a shift number selection circuit 44 selects the number of shifts set by the divisor reference circuit 34a or the divisor reference circuit 34b.

Next, the operation will be described. In the seventh embodiment, the line black level calculation circuit 15 and the frame black level calculation circuit 16 each have a plurality of divisor reference circuits, and one of the divisor reference circuits is selected.

In recent years, the number of pixels of the image sensor 12 has been increased, and accordingly, the time required to read image data from the image sensor 12 tends to increase. This leads to a decrease in response, for example, when adjusting the angle of view in a digital still camera, that is, during finder operation. Therefore, recently, an all-pixel reading mode in which image quality is prioritized during normal shooting and all pixel data is read out, and a high-speed reading mode in which reading is prioritized in viewfinder operation and vertical or horizontal thinning-out is performed are given. There is an imaging device 12 provided. The mode selection signal in FIG. 16 is a signal for selecting the all-pixel reading mode or the high-speed reading mode. In the seventh embodiment, mode 1 is described as the all-pixel reading mode, and mode 2 is described as the high-speed reading mode.

In the seventh embodiment, mode 1
The clip area of the black level in (all pixel read mode) is set to 32 pixels × 512 lines (see FIG. 14), and the clip area in mode 2 (high-speed read mode) is set to 1
It is assumed that the dark current reference value is detected as 6 pixels × 128 lines.

In this case, by setting H′5 as the set value in FIG. 15 in the divisor reference circuit 31a of the line black level calculation circuit 15, the number of horizontal pixels used in mode 1 (all pixel read mode) is set. 32 "and the number of shifts" 5 "are set. In the divisor reference circuit 31b of the line black level calculation circuit 15, H'4 is set as a set value, so that horizontal pixels used in mode 2 (high-speed read mode) are set. The number “16” and the number of shifts “4” are set.

Also, by setting H'9 as a set value in the divisor reference circuit 34a of the frame black level calculation circuit 16, the number of vertical lines used in mode 1 (all pixel reading mode) is shifted to "512". The number “9” is set, and the divisor reference circuit 34 of the frame black level calculation circuit 16 is set.
By setting H'7 as a set value in b, the number of vertical lines “128” and the number of shifts “7” used in mode 2 (high-speed read mode) are set.

Here, mode 1 is selected by the mode selection signal.
When (all-pixel read mode) is selected, the pixel number selection circuit 41 of the line black level calculation circuit 15 outputs the horizontal pixel number “32” to the black level integration circuit 32, and the shift number selection circuit 42 Shift operation circuit 33
Output to Further, the line number selection circuit 43 of the frame black level calculation circuit 16 outputs the number of vertical lines “512” to the black level integration circuit 35, and the shift number selection circuit 44
The number of shifts “9” is output to the shift operation circuit 36. At this time, the black level integration circuits 32 and 35 and the shift operation circuit 3
3 and 36 perform the same operation as in the sixth embodiment,
Here, the description is omitted.

On the other hand, in the mode 2 by the mode selection signal,
When (high-speed read mode) is selected, the pixel number selection circuit 41 of the line black level calculation circuit 15 outputs the horizontal pixel number “1”.
6 "to the black level integration circuit 32, the shift number selection circuit 42 outputs the number of shifts" 4 "to the shift operation circuit 33. The line number selection circuit 43 of the frame black level calculation circuit 16 outputs The number of lines “128” is output to the black level integration circuit 35, and the shift number selection circuit 44 outputs the number of shifts “7” to the shift operation circuit 36.

As is clear from the above, this embodiment 7
According to this, by providing the divisor reference circuit for each mode, it is possible to select the output of the divisor reference circuit only by the mode selection signal. This eliminates the need to rewrite the set values in FIG. 15 when changing the mode, and can reduce the register write operation time. In addition,
In the seventh embodiment, two divisor reference circuits of mode 1 and mode 2 are provided, but the number may be increased as necessary.

Embodiment 8 FIG. FIG. 17 is a block diagram showing a black level correcting apparatus according to Embodiment 8 of the present invention. In the figure, the same reference numerals as those in FIG. Reference numeral 51 denotes a bypass selection circuit (connection means) that outputs the image data output from the A / D converter 14 to the line black level calculation circuit 15 and the correction circuit 19 only when performing black level correction.

Next, the operation will be described. When the bypass control signal indicates that the black level is to be corrected, the bypass selection circuit 51 converts the image data output from the A / D converter 14 into the line black level calculation circuit 15 and the correction circuit 19.
Output to Thus, the correction of the black level is performed in the same manner as in the first embodiment. On the other hand, when the bypass control signal indicates that the black level is not corrected, A /
The image data output from the D converter 14 is not output to the line black level calculation circuit 15 but is output only to the correction circuit 19. As a result, the black level is not corrected, but the line black level calculating circuit 15, the frame black level calculating circuit 16, the time constant data selecting circuit 17 and the time constant calculating circuit 18 are bypassed, and unnecessary operations are avoided. Therefore, power consumption can be reduced.

Embodiment 9 FIG. FIG. 18 is a block diagram showing a black level correcting apparatus according to Embodiment 9 of the present invention. In the figure, the same reference numerals as those in FIG. Numeral 52 outputs the image data corrected by the correction circuit 19 when the correction start permission signal is significant, and the image data output from the A / D converter 14 as it is when the correction start permission signal is insignificant. A correction start selection circuit (correction means) for outputting.

Next, the operation will be described. Immediately after the power is turned on, the dark level stored in the image sensor 12 is in an unstable state, so that it is necessary to prohibit the black level correction operation.
When the operation of the black level correction is prohibited, the correction start permission signal may be made insignificant, and the correction start selection circuit 52 outputs the A / D signal.
The image data output from the converter 14 is output as it is to the outside.

On the other hand, when the correction start permission signal is significant, the correction start selection circuit 52 outputs the image data corrected by the correction circuit 19 to the outside. As is clear above,
According to the ninth embodiment, the presence / absence of black level correction can be arbitrarily set by a correction start permission signal.

Embodiment 10 FIG. FIG. 19 is a configuration diagram showing the inside of the correction circuit 19 of the black level correction device according to the tenth embodiment of the present invention.
2, a designated value setting register for setting a designated value according to the dark current characteristic; 62, a designated value subtracting circuit for subtracting the designated value from the black level reference data calculated by the time constant calculating circuit 18; 63, A / D conversion A black level subtraction circuit for subtracting the subtraction result of the designated value subtraction circuit 62 from the image data output from the unit 14.

Next, the operation will be described. The accumulated dark current depends on the characteristics of the image sensor 12, and when the value of the dark current is high, the data of the black level to be detected is large, which may affect the image quality in the black level correction. In such a case, by preparing a value corresponding to the dark current characteristic of the image sensor 12 in advance, it is possible to reduce the deterioration of the image quality.

That is, the designated value setting register 61 sets a designated value according to the dark current characteristic of the image sensor 12 in advance, and the designated value subtracting circuit 62 receives the black level reference data from the time constant calculating circuit 18 when The specified value is subtracted from the black level reference data. As a result, a value corresponding to an extra dark current is subtracted from the black level reference data.

Then, the black level subtraction circuit 63 outputs the A / D
The subtraction result of the designated value subtraction circuit 62 is subtracted from the image data output from the converter 14. As is clear above,
According to the tenth embodiment, even when the image sensor 12 having a large dark current characteristic is used, the black level can be corrected without deteriorating the image quality.

Embodiment 11 FIG. FIG. 20 is a configuration diagram showing the inside of the correction circuit 19 of the black level correction device according to the eleventh embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 64
Is a designated value setting register for setting a designated value corresponding to the variation of the black level data which fluctuates with the environment, and 65 is set by the black level reference data calculated by the time constant calculating circuit 18 and the designated value setting register 64 The comparison circuit 66 compares the designated value and outputs an enable signal when the black level reference data is larger than the designated value.
5 receives the enable signal from the designated value subtracting circuit 62.
Is output to the black level subtraction circuit 63, and when the enable signal is not received from the comparison circuit 65, the black level reference data output from the time constant calculation circuit 18 is output to the black level subtraction circuit 63. It is a selection circuit.

Next, the operation will be described. Depending on the environment in which the image is taken, the data of the black level may fluctuate greatly, which may affect the image quality when performing the black level correction. In such a case, if the black level reference data is larger than the specified value corresponding to the variation of the black level data, the black level correction is performed by subtracting the specified value from the black level reference data to obtain the image quality. Can be reduced.

That is, the comparison circuit 65 includes the time constant calculation circuit 1
8 and the designated value set by the designated value setting register 64, and outputs an enable signal when the black level reference data is larger than the designated value. Then, when receiving the enable signal from the comparison circuit 65 (when black level reference data> specified value), the black level selection circuit 66 outputs the subtraction result of the specified value subtraction circuit 62 to the black level subtraction circuit 63. On the other hand, the comparison circuit 6
5 (when black level reference data ≦ designated value), the black level reference data output from the time constant calculation circuit 18 is subtracted from the black level subtraction circuit 63.
Output to

As is apparent from the above, the first embodiment
According to 1, even when the black level data greatly fluctuates depending on the environment, the black level can be corrected without deteriorating the image quality.

Embodiment 12 FIG. FIG. 21 is a block diagram showing a black level correcting apparatus according to Embodiment 12 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. Reference numeral 53 denotes a dynamic range correction circuit (correction means) for inputting the image data corrected by the correction circuit 19 and correcting the dynamic range.

Next, the operation will be described. The black level data may fluctuate greatly depending on the environment in which the image is taken. In such a case, the correction circuit 19 outputs image data with a reduced dynamic range. Therefore, in the twelfth embodiment, the dynamic range correction circuit 53 inputs the image data corrected by the correction circuit 19 and corrects the dynamic range, thereby reducing the deterioration of the image quality due to the black level correction.

Embodiment 13 FIG. FIG. 22 is a configuration diagram showing a black level correction apparatus according to Embodiment 13 of the present invention. In the figure, the same reference numerals as those in FIG. 54 is a time constant operation circuit 18
A register selecting circuit for outputting the black level reference data output from the black level register 55 or the black level register 56 in accordance with the field identification signal. The register selection circuit 55 includes black belonging to the first field (first area) in the optical black area. A black level register 56 for storing black level reference data updated based on the average value of the level data; a black level register 56 stores the average value of the black level data belonging to the second field (second area) in the optical black area; A black level register for storing black level reference data updated based on the black level reference data.

Reference numeral 57 denotes a black level operation circuit for calculating an average value of the black level reference data stored in the black level register 55 and the black level reference data stored in the black level register 56, and 58 denotes an operation control signal. The operation selection circuit selects and outputs the black level reference data output from the time constant operation circuit 18 or the average value calculated by the black level operation circuit 57 with reference to the output. Note that the register selection circuit 54, the black level registers 55 and 56, the black level calculation circuit 57, and the operation selection circuit 58 constitute updating means.

Next, the operation will be described. In the all-pixel reading mode, there is an image sensor 12 that outputs image data for each field to form one frame. In the thirteenth embodiment, a description will be given of an image sensor 12 that outputs two fields to form one frame. Here, the field identification signal is a signal provided from outside the black level correction device to identify the first field and the second field, and the frame identification signal indicates the end of the second field, that is, the end of the frame. This is a signal provided from outside to notify. Also,
The operation control signal is a signal for selecting the operation of the first embodiment and the operation of the thirteenth embodiment, and will be described on the assumption that "1" has been notified.

When the time constant calculation circuit 18 outputs the black level reference data in the first field, the register selection circuit 54 inputs the field identification signal indicating the first field from the outside, thereby converting the black level reference data to black. Output to the level register 55. Next, when the time constant calculation circuit 18 outputs the black level reference data in the second field, the register selection circuit 54
By inputting a field identification signal indicating a field, the black level reference data is stored in a black level register 56.
Output to

When a frame identification signal is input from the outside, the black level calculation circuit 57 receives the black level reference data stored in the black level register 55 and the black level register 56.
, And outputs the average to the operation selection circuit 58. The operation selection circuit 58 selects the black level reference data output from the time constant calculation circuit 18 or the average calculated by the black level calculation circuit 57 with reference to the operation control signal, and outputs the selected data to the correction circuit 19. In this example, as described above, since the operation control signal of “1” is given from the outside, the average value calculated by the black level calculation circuit 57 is selected and output to the correction circuit 19.

As is apparent from the above, the first embodiment
According to No. 3, by performing black level correction for every two fields, stable black level correction can be performed even when the black level reference data detected for each field fluctuates.

[0134]

As described above, according to the present invention, the black level reference data is updated from the average value calculated by the average value calculation means and the previous black level reference data, and the updated black level reference data is updated. Is used to correct the black level of the image data, so that it is possible to prevent a sharp change in the black level between the images.

According to the present invention, the average value of the data of the black level per line is calculated.
There is an effect that the in-plane black level correction operation can be performed.

According to the present invention, since the average value of the black level data per frame is calculated, there is an effect that the frame propagation black level correction operation can be performed.

According to the present invention, the average value of the black level data per line is calculated, the average value of the black level data per frame is calculated, and one of the average values is selected. Since the output is provided to the updating means, the frame propagation black level correction operation and the in-plane black level correction operation can be performed without increasing the circuit scale. As a result, there is an effect that a highly versatile black level correction device can be obtained.

According to the present invention, while the previous black level reference data is multiplied by the first weighting value, the average value calculated by the average value calculating means is changed by the second weighting value smaller than the first weighting value. Multiplication is performed, and the results of both multiplications are added to each other to obtain new black level reference data. Therefore, it is possible to prevent a sharp change in black level between images without complicating the configuration. There is an effect that can be.

According to the present invention, the first in the optical black region is provided.
And the average value of the black level data belonging to the second region in the optical black region is calculated, so that one circuit can be used to calculate various values. By selecting the black level correction operation, it is possible to realize highly accurate black level detection. As a result, there is an effect that a more versatile black level correction device can be obtained.

According to the present invention, the first selection means is provided for selecting either one of the average values calculated by the average value calculation means or the black level reference data updated by the update means and outputting the selected data to the correction means. With such a configuration, it is possible to select various black level correction operations with one circuit and realize highly accurate black level detection. As a result, there is an effect that a more versatile black level correction device can be obtained.

According to the present invention, there is provided the second selecting means for selecting the fixed value stored by the fixed value storing means or the black level reference data updated by the updating means and outputting the same to the correcting means. Therefore, it is possible to select various black level correction operations with one circuit and realize highly accurate black level detection. As a result, there is an effect that a more versatile black level correction device can be obtained.

According to the present invention, the third selection means for selecting the initial value stored by the initial value storage means or the black level reference data updated by the updating means and outputting the same to the correction means is provided. Therefore, it is possible to select various black level correction operations with one circuit and realize highly accurate black level detection. As a result, there is an effect that a more versatile black level correction device can be obtained.

According to the present invention, a setting circuit for setting the number of horizontal pixels in the optical black area and setting the number of shifts of the shift operation, and the black level data corresponding to the number of horizontal pixels set by the setting circuit. And an arithmetic circuit that shifts the integration result by the number of shifts to form the average value calculating means. Therefore, a black level correction device with higher versatility without increasing the circuit scale. There is an effect that can be provided.

According to the present invention, the setting circuit for setting the number of vertical lines in the optical black area and setting the number of shifts in the shift operation, and the black level lines by the number of vertical lines set by the setting circuit Since an average value is integrated by an arithmetic circuit that integrates the average value and shifts the integration result by the number of shifts, an average value calculation unit is configured.
There is an effect that a more versatile black level correction device can be provided without increasing the circuit scale.

According to the present invention, the average value calculating means is provided with a plurality of setting circuits, and the arithmetic circuit is configured to select any one of the setting circuits. There is no need to rewrite, and as a result, there is an effect that the register write operation time can be reduced.

According to the present invention, only when the black level is corrected, the image data picked up by the image pickup device is output to the average value calculating means and the correcting means, so that unnecessary operations are avoided. As a result, there is an effect that power consumption can be reduced.

According to the present invention, the image data after correction is output when the correction start permission signal is significant, and the image data before correction is output when the correction start permission signal is insignificant. Therefore, there is an effect that the correction of the black level in a state where the dark current is unstable can be prohibited.

According to the present invention, the designated value is subtracted from the black level reference data updated by the updating means, and the result of the subtraction is subtracted from the image data. Therefore, an image sensor having a large dark current characteristic is used. In this case, the black level can be corrected without deteriorating the image quality.

According to the present invention, when the black level reference data updated by the updating means is larger than the specified value, the specified value is subtracted from the black level reference data, and the subtraction result is subtracted from the image data. When the black level reference data is not larger than the specified value, the black level reference data is subtracted from the image data. There is an effect that the black level can be corrected without inviting.

According to the present invention, since the dynamic range is corrected after the black level of the image data is corrected, there is an effect that deterioration in image quality due to the black level correction can be reduced.

According to the present invention, the first in the optical black region
And the black level reference data updated based on the average value of the black level data belonging to the second region in the optical black region. Since the average value with the data is calculated, there is an effect that stable black level correction can be performed even when the black level reference data detected for each field varies.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a black level correction device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a sensor surface of an image sensor such as a CCD.

FIG. 3 is an explanatory diagram showing a selection result of a time constant data selection circuit.

FIG. 4 is a configuration diagram showing a black level correction device according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a sensor surface of an image sensor such as a CCD.

FIG. 6 is an explanatory diagram showing a selection result of a time constant data selection circuit.

FIG. 7 is a configuration diagram showing a black level correction device according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram illustrating a selection result of a time constant data selection circuit and a selection circuit.

FIG. 9 is a configuration diagram illustrating a black level correction device according to a fourth embodiment of the present invention.

FIG. 10 is an explanatory diagram showing selection results of a time constant data selection circuit and a selection circuit.

FIG. 11 is a configuration diagram showing a black level correction device according to a fifth embodiment of the present invention.

FIG. 12 is an explanatory diagram showing selection results of a time constant data selection circuit and a selection circuit.

FIG. 13 is a configuration diagram showing the insides of a line black level calculation circuit and a frame black level calculation circuit of a black level correction device according to a sixth embodiment of the present invention.

FIG. 14 is an explanatory diagram showing a sensor surface of an image sensor such as a CCD.

FIG. 15 is an explanatory diagram showing set values of a divisor reference circuit.

FIG. 16 is a configuration diagram showing the insides of a line black level calculation circuit and a frame black level calculation circuit of a black level correction device according to a seventh embodiment of the present invention.

FIG. 17 is a configuration diagram showing a black level correction device according to an eighth embodiment of the present invention.

FIG. 18 is a configuration diagram showing a black level correction device according to a ninth embodiment of the present invention.

FIG. 19 is a configuration diagram showing the inside of a correction circuit of a black level correction device according to a tenth embodiment of the present invention.

FIG. 20 is a configuration diagram showing the inside of a correction circuit of a black level correction device according to Embodiment 11 of the present invention.

FIG. 21 is a configuration diagram showing a black level correction device according to a twelfth embodiment of the present invention.

FIG. 22 is a configuration diagram showing a black level correction device according to Embodiment 13 of the present invention.

FIG. 23 is a configuration diagram showing a conventional black level correction device.

[Explanation of symbols]

Reference Signs List 11 lens system, 12 image sensor, 13 analog processing unit, 14 A / D converter, 15 line black level calculation circuit (average value calculation means), 15a, 15b line black level calculation circuit (average value calculation means), 16 frames Black level calculation circuit (average value calculation means), 16a, 16b Frame black level calculation circuit (average value calculation means), 17 time constant data selection circuit (average value calculation means), 18 time constant calculation circuit (update means), 19 Correction circuit (correction means), 2
0 frame black level averaging circuit (mean value calculating means), 2
1 time constant data selection circuit (mean value calculation means), 22
Selection circuit (first selection means), 23 black level fixed value storage section (fixed value storage section), 24 selection circuit (second selection section), 25 black level initial value storage section (initial value storage section), 26 Selection circuit (third selection means), 31, 31
a, 31b divisor reference circuit (setting circuit), 32 black level integration circuit (arithmetic circuit), 33 shift operation circuit (arithmetic circuit), 34, 34a, 34b divisor reference circuit (setting circuit), 35 black level integrator circuit (calculation) Circuit), 36 shift operation circuit (operation circuit), 41 pixel number selection circuit, 4
2 shift number selection circuit, 43 line number selection circuit, 44
Shift number selection circuit, 51 bypass selection circuit (connection means), 52 correction start selection circuit (correction means), 53 dynamic range correction circuit (correction means), 54 register selection circuit (update means), 55, 56 black level registers ( Updating means), 57 black level calculating circuit (updating means), 58 operation selecting circuit (updating means), 61 designated value setting register, 62 designated value subtracting circuit, 63 black level subtracting circuit, 64 designated value setting register, 65 comparing circuit , 66 Black level selection circuit.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // H04N 101: 00 H04N 1/40 101Z F term (reference) 5B057 AA20 BA02 BA29 BA30 CA08 CA12 CA16 CB08 CB12 CB16 CE11 CH08 CH18 5C021 PA76 XA03 YA08 5C022 AC42 AC69 5C024 BX01 CX32 GY01 5C077 LL01 MM03 PP12 PP14 PP45 PP46 PQ08 PQ18

Claims (18)

[Claims] 1. An average value calculating means for calculating an average value of black level data belonging to an optical black area in image data picked up by an image sensor, and an average value calculated by the average value calculating means. A black level comprising: updating means for updating the black level reference data from the previous black level reference data; and correcting means for correcting the black level of the image data using the black level reference data updated by the updating means. Correction device. 2. The black level correction device according to claim 1, wherein the average value calculation means calculates an average value of black level data per line. 3. The black level correction device according to claim 1, wherein the average value calculation means calculates an average value of black level data per frame. 4. An average value calculating means calculates an average value of black level data per line, calculates an average value of black level data per frame, and selects one of the average values. 2. The black level correction device according to claim 1, wherein the output is output to an updating unit. 5. The updating means multiplies the previous black level reference data by a first weighting value, and updates the average value calculated by the average value calculating means with a second weighting value smaller than the first weighting value. The black level correction device according to any one of claims 1 to 4, wherein the multiplication is performed, and the results of the multiplication are added to each other to obtain new black level reference data. 6. An average value calculating means calculates an average value of black level data belonging to a first area in the optical black area, and calculates an average value of black level data belonging to a second area in the optical black area. The black level correction device according to any one of claims 1 to 5, wherein an average value of the data is calculated. 7. A first selection means for selecting either one of the average values calculated by the average value calculation means or the black level reference data updated by the update means and outputting the selected data to the correction means. The black level correction device according to claim 6, wherein 8. A fixed value storage means for storing a fixed value of a desired black level, and a correction means for selecting the fixed value stored by the fixed value storage means or the black level reference data updated by the updating means. 8. The black level correction device according to claim 6, further comprising a second selection unit that outputs the data to the black level correction unit. 9. An initial value storing means for storing an initial value of a desired black level, and a correcting means for selecting the initial value stored by the initial value storing means or the black level reference data updated by the updating means. 9. The black level correction apparatus according to claim 6, further comprising a third selection unit that outputs the black level to the black level correction unit. 10. A setting circuit for setting the number of horizontal pixels in an optical black area and setting the number of shifts in a shift operation, and integrating black level data by the number of horizontal pixels set by the setting circuit. 5. The black level correction device according to claim 2, wherein an average value calculating means comprises an arithmetic circuit for performing a shift operation of the integration result by the number of shifts. 11. A setting circuit for setting the number of vertical lines in an optical black region and setting the number of shifts in a shift operation, and integrating a line average value of a black level by the number of vertical lines set by the setting circuit. 5. The black level correction device according to claim 3, wherein an average value calculating means comprises an arithmetic circuit for shifting the integration result by the number of shifts. 12. The black level correction device according to claim 10, wherein the average value calculation means includes a plurality of setting circuits, and the arithmetic circuit selects one of the setting circuits. 13. The image processing apparatus according to claim 1, further comprising a connection unit that outputs image data picked up by the image pickup device to an average value calculation unit and a correction unit only when black level correction is performed. 13. The black level correction device according to claim 12. 14. The correction means outputs image data after correction when the correction start permission signal is significant, and outputs image data before correction when the correction start permission signal is insignificant. 13. The black level correction device according to claim 1, wherein: 15. The method according to claim 1, wherein the correction unit subtracts the designated value from the black level reference data updated by the updating unit, and subtracts the subtraction result from the image data. The black level correction device according to claim 1. 16. When the black level reference data updated by the updating means is larger than a specified value, the correction means subtracts the specified value from the black level reference data and subtracts the subtraction result from the image data. The black level according to any one of claims 1 to 14, wherein the black level reference data is subtracted from the image data when the black level reference data is not larger than the designated value. Correction device. 17. The method according to claim 1, wherein the correction means corrects a black level of the image data and then corrects a dynamic range.
Item 6. The black level correction device according to item 1. 18. An updating means for updating black level reference data based on an average value of black level data belonging to a first area in an optical black area and a second level in the optical black area.
7. The black level correction device according to claim 6, wherein the average value with the updated black level reference data is calculated based on the average value of the black level data belonging to the region.