JPH09247521A - Shading correcting method and image pickup device dealing with successive scanning system provided with shading correcting function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute correct shading correction. SOLUTION: The output signal of the CCD image pickup element 1 of a frame interline transfer type is converted into a progressive scanning signal by a successive scanning conversion circuit 4, and is outputted. On the basis of the successive scanning signal converted by the successive scanning conversion circuit 4, desired data for shading correction is detected by an odd/even numbered line data detection circuit 7 separately for an odd and an even numbered lines. The separation of the odd and the even numbered line at the time of data detection in the successive scanning signal is executed by an odd/ numbered line switching circuit 9. Further, by calculating a shading correction signal corresponding to each line by a shading correction signal calculation circuit 10 from the data of the odd and the even numbered lines detected by the odd/even numbered line data detection circuit 7 by switching the odd line and the even numbered line, shading in an image pickup device dealing with a successive scanning system is suppressed correctly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus compatible with a progressive scanning method, and more particularly to an image pickup apparatus compatible with a progressive scanning method having a shading correction function.

[0002]

2. Description of the Related Art In recent years, it has become necessary to use an image pickup apparatus such as an EDTV 2 which performs a sequential scanning operation. Further, a new frame interline transfer type Charge Coupled Device image pickup device (hereinafter referred to as FIT-CCD) has been proposed in order to realize the progressive scanning operation.

FIG. 5 is a block diagram showing the internal structure of the FIT-CCD. As shown in FIG. 5, this FIT-CCD has an odd line photoelectric conversion unit 9, an even line photoelectric conversion unit 10, a vertical transfer line 11, and an odd line storage area 1.
2, an even line storage area 13, and a horizontal transfer line 24. The details of the FIT-CCD are described in, for example, the following three documents. First
, K. Itakura et al., "A Multiple Frame-Interline-T
ransfer (M-FIT) CCD for Progressive-Scan Camera Syst
em ", ISSCC Digest of Technical Paper, pp190-191; Fe
b., 1993, Secondly, Shinden et al. "2/3 inch 520,000 pixel 16: 9 image sensor" ITE Technical Report Vol.1
7, No16, IPU93-13, CE93-12; Mar., 1993, Third, Itakura
In addition, there is "Sequential scanning M-FIT CCD image sensor-2 / 3 inch 520,000 pixel CCD compatible with wide vision-" IEICE Technical Report, PP65-7, ICD93-121; Oct., 1993.

FIG. 6 is a signal timing diagram showing the image pickup signal output of the FIT-CCD. The new FIT-CCD will be described below with reference to FIGS. 5 and 6.
Signal (charge) converted by the even-line photoelectric conversion unit 10
Is transferred to the vertical transfer line 11 by the first read pulse, and the transferred signal is transferred to the odd line storage area 12 by the high speed transfer pulse. Thereafter, the signal (charge) converted by the odd line photoelectric conversion unit 9 is transferred to the vertical transfer line 11 by the second read pulse, and then the even line signal stored in the odd line storage area 12 is transferred by the high speed transfer pulse. Even line storage area 13
And the odd line signal transferred to the vertical transfer line 11 are transferred to the odd line storage area 12.

Thereafter, the signals transferred to the even line storage area 13 and the odd line storage area 12 are transferred to the horizontal transfer line 24 one line at a time during the horizontal blanking period, and the signals transferred to the horizontal transfer line 24 are transferred horizontally. The pulses are sequentially sent out as the output of the image pickup device in synchronization with horizontal scanning. Note that the reading of signals from the even line photoelectric conversion unit 10 and the odd line photoelectric conversion unit 9 is performed within the vertical blanking period. In addition, the horizontal transfer line 24
The output of all signals from 1 to 3 is performed within one field period.

The image signal output of such an operation is as shown in FIG. That is, all the odd-numbered line signals are output in about half the period of one field, and all the even-numbered line signals are output in the remaining half period. Then, the even-numbered line signal and the odd-numbered line signal output from the image sensor are alternately output for each horizontal scanning line, thereby sequentially outputting the scanning signal.

FIG. 7 is a block diagram showing the structure of a progressive scanning type image pickup device using the image pickup element having the above structure.
As shown in FIG. 7, this progressive scan system compatible imaging device
The image sensor 1 having the above-described configuration, amplification of an output signal of the image sensor 1,
A pre-process circuit 2 that performs pre-processing such as addition and subtraction of various correction signals, an AD that converts an analog signal into a digital signal
A converter 3, a progressive scan conversion circuit 4 for alternately outputting an even line signal and an odd line signal for each horizontal scanning line,
It comprises a process circuit 5 for performing processing such as gamma correction and matrix operation, and a DA converter 6 for converting a digitized signal into an analog signal.

The operation of the progressive scan type image pickup apparatus configured as described above will be described below. First, an image pickup signal output shown in FIG. 6 is obtained from the image pickup device 1 having the above-described configuration, preprocessing such as amplification is performed in the preprocess circuit 2, the digital signal is converted by the AD converter 3, and then the sequential scanning is performed. In the conversion circuit 4, even line signals and odd line signals are alternately output for each horizontal scanning line so as to be in a regular order. The output of the progressive scan conversion circuit 4 which has been converted into the normal order is subjected to gamma processing, matrix calculation and other processing in the process circuit 5, and converted into an analog signal in the DA converter 6 for output.

FIG. 8 is a block diagram showing the arrangement of a progressive scanning type image pickup apparatus with a shading correction function, which uses the image pickup element having the above arrangement. As shown in FIG. 8, an image pickup apparatus with a progressive scanning method having a shading correction function has a preprocess circuit 2 for performing preprocessing such as an image pickup element 1 having the above-described configuration, amplification of an output signal of the image pickup element 1, addition and subtraction of various correction signals. , A to convert analog signals to digital signals
D converter 3, progressive scan conversion circuit 4 for alternately outputting even line signals and odd line signals for each horizontal scanning line, process circuit 5 for performing processing such as gamma correction and matrix operation, and digitized signals for analog A DA converter 6 for converting into a signal, a data detection circuit 12 for detecting a signal state by dividing a captured image into a plurality of blocks,
The shading correction signal calculation circuit 10 calculates a shading correction amount from the value detected by the data detection circuit 12, and the shading correction memory 11 stores the shading correction data calculated by the shading correction signal calculation circuit 10.

The operation of the progressive scan type image pickup device with a shading correction function configured as described above will be described below. First, the image sensor 1 having the above configuration
6, the imaging signal output shown in FIG. 6 is obtained, pre-processing such as amplification is performed in the pre-process circuit 2, the digital signal is converted in the AD converter 3, and then the normal scanning is performed in the progressive scan conversion circuit 4. So that the even-numbered line signal and the odd-numbered line signal are alternately output for each horizontal scanning line. The output of the progressive scan conversion circuit 4 which has been converted into the normal order is subjected to gamma processing, matrix calculation and other processing in the process circuit 5, and converted into an analog signal in the DA converter 6 for output.

The output of the progressive scan conversion circuit 4 is also supplied to the data detection circuit 12 at the same time.
Then, the output of the progressive scan conversion circuit 4 is divided into a plurality of blocks, and the image data of each block is detected. The detected image data is, for example, data that is a basis for shading correction, such as an average value of image data in a block. The detected image data is compared by the shading correction signal calculation circuit 10 with the average value data of each block detected with the diaphragm closed, for example, to determine whether the average value data with respect to each block with the diaphragm closed. The black shading correction data is calculated such that the average values of the blocks are equal, and the obtained black shading correction data is stored in the shading correction memory 11. The shading correction data accumulated in the shading correction memory 11 is fed back to the pre-process circuit 2 or the like to perform the shading correction.

[0012]

However, in the progressive scan type image pickup device of FIG. 7 which uses the image pickup device having the above-mentioned structure, there is a difference in the time accumulated in the storage units in the image pickup devices of even lines and odd lines. Occurs, the amount of shading changes due to the effect of dark current. As a result, the amount of shading greatly differs for each line in the progressive scanning signal after the combination of the odd line and the even line, which causes a problem that a horizontal streak image is unsightly.

Further, in the shading correction circuit portion of the progressive scanning type image pickup apparatus with a shading correction function using the image pickup element having the above-mentioned configuration, the odd line and the even line having different shading amounts are combined,
Since the shading correction amount is calculated by averaging, there is a problem that accurate correction cannot be performed. In view of such a point, the present invention separates the odd line and the even line in the block for data detection, and calculates the shading correction amount for the odd line and the even line separately,
It is an object of the present invention to perform accurate shading correction in a progressive scanning type image pickup device with a shading correction function using the image pickup device having the above-described configuration by performing the correction.

[0014]

In order to achieve the above object, a shading correction method according to a first aspect of the present invention reads an odd line signal group and an even line signal group accumulated in a photoelectric conversion unit at different timings, The timings for outputting all the signals within one field period are different at the output timings of all the odd-numbered line signal groups and the output timings of all the even-numbered line signal groups. When converting to a scanning signal, it is a method of performing a shading correction for a progressive scanning signal, the data that is the basis for determining the shading correction amount from the sequential scanning signal is detected by dividing it into an odd line and an even line,
Shading correction signals are calculated separately for the odd line and the even line based on the detected data, and the shading correction is performed for the odd line and the even line separately for the sequential scanning signal.

Further, according to the progressive scanning type image pickup device with the shading correction function of the second aspect, the signal group of the odd line and the signal group of the even line accumulated in the photoelectric conversion unit are read out at different timings and within one field period. The timing for outputting all signals is different between the timing of outputting all the signal groups of the odd line and the timing of outputting all of the signal groups of the even line, and the output signals of the imaging elements are sequentially scanned. A progressive scan conversion circuit for converting into a signal, an output signal of the progressive scan conversion circuit is divided into an odd line and an even line, and an odd / even line data detection circuit for detecting data which is a basis of shading correction,
Equipped with an odd / even line switching circuit for switching whether the signal detected by the odd / even line data detection circuit is an odd line or an even line, and the shading correction signal is calculated separately for the odd line and the even line. Then, the shading correction is performed separately for the odd line and the even line.

Further, according to the third aspect of the present invention, there is provided a progressive scanning type image pickup device with a shading correction function, which reads out the signal groups of the odd lines and the signal groups of the even lines accumulated in the photoelectric conversion section at different timings, and within one field period. The timing for outputting all signals differs between the image sensor and the output signal of the image sensor, which differ between the timing of outputting all the signal groups of the odd line and the timing of outputting all of the signal groups of the even line. A preprocessing circuit that performs preprocessing such as amplification and addition / subtraction of various correction signals, and A that converts the output signal of the preprocessing circuit from analog to digital
A D converter, a progressive scan conversion circuit that converts the output signal of the AD converter into a progressive scan signal, a process circuit that performs processing such as gamma correction and matrix calculation on the output signal of the progressive scan conversion circuit, and a process circuit The DA converter for converting the output signal of the digital signal from the analog signal to the analog signal and the output signal of the progressive scan conversion circuit are divided into the odd line and the even line to detect the data which is the basis of the shading correction.
Detected by an even line data detection circuit, an odd / even line switching circuit for switching the signal detected by the odd / even line data detection circuit to an odd line or an even line, and an odd / even line data detection circuit Shading correction signal calculation circuit for separately calculating the shading correction signal for the odd line and the even line from the data obtained, and the shading correction for storing the shading correction signal separately calculated for the odd line and the even line by the shading correction signal calculation circuit A shading correction signal is read from the shading correction memory and given to the pre-processing circuit so that the shading correction is performed separately for the odd line and the even line.

According to the present invention, the odd line and the even line are separated and different shading correction signals are calculated, and different shading amounts of the even line and the odd line are separately corrected. Therefore, it is possible to accurately suppress the shading in the imaging device supporting the progressive scanning method with the shading correction function and obtain a higher quality image.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a progressive scanning type imaging device with a shading correction function according to an embodiment of the present invention. As shown in FIG. 1, the progressive scanning type image pickup device with a shading correction function includes an image pickup element 1 having the above-described configuration, a preprocess circuit 2 for performing preprocessing such as amplification of an output signal of the image pickup element 1, addition and subtraction of various correction signals. , An AD converter 3 for converting an analog signal into a digital signal, a progressive scan conversion circuit 4 for alternately outputting an even line signal and an odd line signal every horizontal scanning line, a process for performing processing such as gamma correction and matrix calculation A circuit 5, a DA converter 6 for converting a digitized signal into an analog signal, an odd / even line data detection circuit for dividing a picked-up image into a plurality of blocks and detecting a signal state of an odd line or an even line in the block Shady correction amount is calculated from the value detected by the odd / even line data detection circuit 7. Correction signal calculation circuit 10, shading correction memory 11 for storing shading correction data calculated by the shading correction signal calculation circuit 10, and shading correction data for odd / even lines are distinguished and output at the timing shown in FIG. The memory control circuit 8 controls the shading correction memory 11 so as to perform the correction in accordance with the output of the image sensor, and the switching circuit 9 for detecting the signal states of the odd line and the even line, respectively.

The operation of the progressive scan type image pickup apparatus with a shading correction function of the present embodiment configured as described above will be described below. First, the image pickup signal output shown in FIG. 6 is obtained from the image pickup device 1 having the above-mentioned configuration, preprocessing such as amplification and addition / subtraction of various correction signals is performed in the preprocess circuit 2, and the AD converter 3 converts it into a digital signal. After that, the progressive scan conversion circuit 4 alternately outputs the even line signal and the odd line signal for each horizontal scanning line so as to be in a regular order. The output of the progressive scan conversion circuit 4 which has been converted into the normal order is subjected to gamma processing, matrix calculation and other processing in the process circuit 5, and converted into an analog signal in the DA converter 6 for output.

The output of the progressive scan conversion circuit 4 is simultaneously supplied to the odd / even line data detection circuit 7. The odd / even line data detection circuit 7 detects the image data of the odd line or even line of each block divided into a plurality of blocks in accordance with the switching signal of the odd / even line switching circuit 9. The detected image data is, for example, data that is a basis for calculating a shading correction amount, such as an average value of image data in a block. The detected odd-numbered or even-numbered line image data is compared by the shading correction signal calculation circuit 10 with the comparison of the average value data of the respective blocks detected with the diaphragm closed, thereby closing the diaphragm. The black shading correction data such that the average value of the odd line or the even line in each block in the set state is equal is calculated separately for each of the odd line and the even line, and the memory control circuit 8 performs the shading correction memory. It is stored in 11.

At this time, the odd / even line switching circuit 9
Of the shading correction memory 11 so that odd-numbered or even-numbered shading correction data can be distinguished by the switching signal and the image sensor output output at the timing shown in FIG. The read control is performed by the memory control circuit 8. Further, the shading correction data separately stored in the shading correction memory 11 for odd lines or even lines is stored in the shading correction memory 1 at the time of shooting.
1 and fed back to the pre-processing circuit 2 and the like, and the odd line and the even line having different shading amounts are separately corrected, and the progressive scan type imaging with the shading correction function using the above-described image sensor 1 is performed. Accurate shading correction can be performed in the device.

Next, the state of shading correction will be described in detail. FIG. 2 and FIG. 3 are schematic diagrams showing the state of shading amounts in a progressive scanning type imaging device with a shading correction function. FIG. 2 is a schematic diagram showing the relationship between the image pickup signal output and the shading amount of the image pickup device 1 having the above configuration, and FIG. 3 is a schematic diagram showing the relationship between the progressive scan conversion circuit output and the shading amount. That is,
As shown in FIG. 2, in the output of the image sensor, the shading amount changes smoothly according to the time difference accumulated in the accumulating unit, but after the sequential scan conversion as shown in FIG. Since the even number lines and the odd number lines are alternately output for each horizontal scanning line, the shading amount greatly differs for each line, and the entire image becomes an unsightly image on the horizontal stripes.

FIG. 4 shows the odd / even line data detection circuit 7
An example of the shading amounts of the even lines and the odd lines detected in 1. That is, the image data of the odd line and the even line is detected for each block obtained by dividing the screen into 24. For example, in the A1 block, the detection data of the even lines is DSE _A1 obtained by averaging the shading amounts of the dotted lines in FIG. 4, and the detection data of the odd lines in the A1 block is DSO _A1 obtained by averaging the shading amounts of the solid lines in FIG. Is the value
These values accurately detect the shading amounts of the even line portion of the A1 block and the odd line portion of the A1 block in FIG. In addition, DSE _A1 , DSO
_A1 for even-numbered lines and than calculating the shading correction signal for odd-numbered lines, at the preprocess circuit 2 may be carried out accurately each shading correction of odd lines of even-numbered line portions and the A1 block of A1 block of FIG.

As described above, according to this embodiment,
By calculating the shading correction signals by separating the odd line and the even line, respectively, the different shading amounts of the even line and the odd line are separately corrected. It is possible to accurately suppress shading and obtain a higher quality image.

In the data detection in the above embodiment, the screen is divided into 24 blocks.
It is not limited to individuals. Further, although the screen division in the embodiment divides the entire screen into equal blocks, it is not limited to equal block division. Further, the detection data detected by the odd / even line data detection circuit in the embodiment is the average value of the image data, but this is not limited to the average value, and it may be the image data for calculating the shading correction amount. Obviously, the invention can be constructed.

Further, in the calculation of the shading correction amount in the embodiment, the average value data for each block detected with the diaphragm closed is compared to determine the magnitude.
The calculation was performed by calculating the black shading correction data such that the average value of the odd line or the even line in each block in the state where the diaphragm is closed is equal, but the invention is not limited to this, and for example, the reference value A method of calculating the difference amount or a method of calculating the shading correction amount by combining the interpolation process may be used.

[0027]

As described above, according to the progressive scan type image pickup apparatus with the shading correction function of the present invention, the shading correction amount is calculated separately for the odd line and the even line, and the odd line and the even line are calculated. Since the shading correction is performed separately, it is possible to accurately suppress the shading in the image capturing apparatus compatible with the progressive scanning method and obtain a higher quality image.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a progressive scanning type imaging device with a shading correction function according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a relationship between an imaging output of a conventional FIT-CCD compatible with a progressive scanning method and a shading amount.

FIG. 3 is a schematic diagram showing a relationship between a progressive scan conversion circuit output and a shading amount.

FIG. 4 is a schematic diagram for explaining how the odd / even line data detection circuit detects the image data for the odd lines and the image data for the even lines separately.

FIG. 5 is a schematic diagram showing an internal configuration of a conventional FIT-CCD compatible with a progressive scanning method.

FIG. 6 is a schematic diagram showing imaging output timing of a conventional FIT-CCD compatible with a progressive scanning method.

FIG. 7 is a block diagram showing a configuration of a conventional progressive-scan-compatible image pickup apparatus.

FIG. 8 is a block diagram showing a configuration of a conventional progressive scan system compatible image pickup device with a shading correction function.

[Explanation of symbols]

 1 Image sensor compatible with progressive scanning method 2 Pre-process circuit 3 AD converter 4 Progressive scanning conversion circuit 5 Process circuit 6 DA converter 7 Odd / even line data detection circuit 8 Memory control circuit 9 Odd / even line switching circuit 10 Shading correction Signal calculation circuit 11 Shading correction memory 12 Data detection circuit

Claims (3)

[Claims] 1. The odd-line signal is read at a timing for reading out the odd-line signal group and the even-line signal group accumulated in the photoelectric conversion unit at different timings, and outputting all signals within one field period. Shading for performing shading correction on the sequential scanning signal when converting the output signals of the image pickup device, which are different at the timing of outputting all the groups and the timing of outputting all of the even-numbered signal groups, to the sequential scanning signals A method of correction, wherein the data that is the basis for determining the shading correction amount from the progressive scan signal is divided into an odd line and an even line and detected, and the odd line and the even line are shaded based on the detected data. The correction signal is calculated separately, and the odd scan lines and the even scan lines are separately shaded with respect to the progressive scan signal. Shading correction method and performing grayed correction. 2. The odd line signal is read at different timings when the odd line signal group and the even line signal group accumulated in the photoelectric conversion unit are read out at different timings. An image pickup element that differs at the timing of outputting all of the groups and the timing of outputting all of the signal groups of the even lines; a progressive scan conversion circuit that converts the output signal of the image pickup element into a progressive scan signal; and the progressive scan conversion An output signal of the circuit is divided into an odd line and an even line to detect the data that is the basis of shading correction, and an odd / even line data detection circuit detects the signal detected by the odd / even line data as an odd line. Equipped with an odd / even line switching circuit for switching between the even line and the even line. Over loading correction signal shading correction function interlace corresponding imaging apparatus is characterized in that so as to separate shading correction in odd and even lines is calculated separately. 3. The odd-line signal is read at a different timing when the odd-line signal group and the even-line signal group accumulated in the photoelectric conversion unit are read out at different timings. An image sensor that differs in the timing of outputting all the groups and the timing of outputting all of the signal groups in the even-numbered lines, and a pre-processing that performs preprocessing such as amplification and addition / subtraction of various correction signals on the output signal of the image sensor. A process circuit, an AD converter that converts the output signal of the pre-process circuit from analog to digital, a progressive scan conversion circuit that converts the output signal of the AD converter into a progressive scan signal, and an output of the progressive scan converter circuit Gamma correction on the signal,
A process circuit that performs processing such as matrix operation, a DA converter that converts the output signal of the process circuit from digital to analog, and an output signal of the progressive scan conversion circuit that is divided into odd lines and even lines for shading correction. Odd / even line data detection circuit for detecting the underlying data, and odd / even line switching circuit for switching whether the signal detected by the odd / even line data detection circuit is an odd line or an even line And a shading correction signal arithmetic circuit for separately calculating a shading correction signal for an odd line and an even line from the data detected by the odd / even line data detection circuit, and an odd line and an even line for the shading correction signal arithmetic circuit. The shading correction signal calculated separately with Shading correction function, wherein the shading correction signal is read from the shading correction memory and given to the pre-processing circuit to perform shading correction separately for odd lines and even lines. Sequential scanning system compatible imaging device.