JP2003250091A - Apparatus for detecting defective pixel of solid-state imaging element and electronic camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for detecting a defective pixel of a solid-state imaging element capable of detecting a defective pixel in a short time with a simple configuration and to provide an electronic camera employing the same. <P>SOLUTION: The apparatus for detecting a defective pixel is configured with: an accumulating section 6 for accumulating image data outputted from a solid-state imaging element 3 by each optional block; a memory 5 for temporarily storing the accumulated value obtained by the accumulating section, storing the image data and temporarily storing information with respect to a defective pixel; a CPU 7 for selecting a block from which the defective pixel is detected on the basis of the accumulated value to detect the defective pixel from the image data included in the block; and a nonvolatile memory 8 for permanently storing defective pixel information. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image sensor defective pixel detection device for electrically detecting a defective pixel generated on or in an image output from a solid-state image sensor, and a defective pixel detection device. The present invention relates to an electronic camera using the device.

[0002]

2. Description of the Related Art Generally, a solid-state image sensor may have defective pixels due to dust adhesion, crystal defects, or the like. In particular, a solid-state image sensor having many pixels has a high occurrence frequency of defective pixels, and a technique for detecting and correcting the defective pixels is indispensable. One method of such detection / correction technique is disclosed in, for example, Japanese Patent Laid-Open No. 11-220661. The proposal is made in the publication.

By the way, the defect of the solid-state image pickup device has a change with time such that defective pixels are generated while the solid-state image pickup device is used. However, the method of detecting and storing the defective pixel position in advance and correcting it based on the stored position information as in the prior art disclosed in the above publication cannot cope with the change with time.

Therefore, as a technique for coping with changes over time,
Japanese Patent Laid-Open No. 10-322603 discloses that when power is turned on,
One screen is photographed by CCD with the aperture closed and in a pitch dark state, the image obtained by the photographing is compared with a threshold value, and when the image data shows a higher brightness than the threshold value, a defective pixel (white defect) In the state where the defective pixel detection mode is selected by the mode switch, the camera is pointed at a dedicated subject, one screen is photographed by the CCD, and the image data obtained by the photographing is compared with a threshold value. An electronic camera is disclosed which detects defective pixels (black scratches) when the image data has a luminance lower than the threshold value.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the method disclosed in Japanese Patent No. 2603, it is possible to detect a defective pixel caused by the change over time of the solid-state imaging device. However, when the power is turned on, one screen of image capturing and defective pixel detection processing are performed. Therefore, there is a problem in that it takes a long time to start the electronic camera. Also, switching to the defect detection mode and shooting a dedicated subject,
There is also a problem in that the user of the electronic camera has troublesome work. As described above, in the method in which an image dedicated to defect detection is captured and defective pixel detection is performed using the image data, detection accuracy is high, but processing time increases and operations that are not necessary for original imaging occur. There is a problem.

The present invention has been made to solve the above-mentioned problems in the conventional defective pixel detection system of a solid-state image pickup device. The invention according to claims 1 to 12 uses an image dedicated to defect detection. It is an object of the present invention to provide a defective pixel detection device for a solid-state image sensor, which is capable of detecting defective pixels with high accuracy in a short time. Further, the invention according to claims 13 to 20 aims to provide an electronic camera using the defective pixel detection device of the solid-state image pickup device, which enables appropriate defective pixel detection according to various imaging conditions. And

[0007]

In order to solve the above problems, the invention according to claim 1 is a cumulative addition means for cumulatively adding image data output from a solid-state image pickup device for each arbitrary block, Block selecting means for selecting a block for performing defective pixel detection using the cumulative addition value by the cumulative adding means, and defect detecting means for performing defective pixel detection in the block using image data included in the selected block, A defective pixel detection device for a solid-state image sensor is configured with a storage unit that stores information about the detected defective pixel.

In the defective pixel detecting device having such a configuration, the block for which the defective pixel is detected by the defect detecting means can be appropriately selected by the block selecting means, so that the defective pixel detecting process can be performed in a short time. It will be possible.

According to a second aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the first aspect, the storage means detects an area for storing defective pixel position information detected at the time of factory shipment, and detects after the factory shipment. The defective pixel position information detected at the time of factory shipment is not updated.

In the defective pixel detecting device thus constructed, the defective pixel position information at the time of factory shipment is not overwritten and erased when detecting and storing the defective pixel generated due to aging. Since the defective pixel detected at the time of factory shipment is detected with extremely high accuracy, it is possible to perform highly accurate defective pixel correction by protecting this defective pixel position information.

According to a third aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the first aspect, the cumulative addition means accumulates each color when the solid-state image pickup device includes a Bayer array color filter. It is characterized in that it is configured to calculate an addition value.

In the defective pixel detection device thus constructed, the defective pixel detection is performed by selecting a block based on the cumulative addition value of each color of R, Gr, Gb and B, so that it is not affected by the Bayer array color filter. It is possible to detect defective pixels with high accuracy.

According to a fourth aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the first aspect, the cumulative addition means is arranged for each color when the solid-state image pickup device includes a complementary color mosaic array color filter. It is characterized in that it is configured to calculate a cumulative addition value.

In the defective pixel detection device thus constructed, the defective pixel detection is performed by selecting a block based on the cumulative addition value of each color of Mg, G, Ye and Cy, so that the complementary color mosaic array color filter is affected. It is possible to detect defective pixels with high accuracy.

According to a fifth aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the first aspect, the cumulative addition means is composed of a CMOS image pickup device, and the output of the CMOS image pickup device is arranged for each column and each row. It is characterized in that it is configured to perform cumulative addition.

In the defective pixel detecting device having such a configuration, the number of data to be cumulatively added is reduced, so that the time required for the defective pixel detecting process can be further shortened.

According to a sixth aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the first aspect, the block selection means compares the cumulative addition value with a bright block determination threshold value and a dark block determination threshold value, and accumulates them. When the added value is larger than the bright block determination threshold value or smaller than the dark block determination threshold value, the block is configured to be selected as a block to be subjected to defective pixel detection processing.

In the defective pixel detection device having such a configuration, it is possible to select a uniformly bright block or a uniformly dark block that facilitates defective pixel detection, and it is possible to improve the defective pixel detection accuracy. . Further, since there is a tendency in the position where a uniformly bright block or a uniformly dark block appears at the time of shooting, the defective pixel detection is preferentially continued for the uniformly bright block or the uniformly dark block. As a result, it becomes possible to efficiently detect defective pixels at positions that are easily noticeable.

According to a seventh aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the first aspect, the block selection means is a cumulative addition value, a bright block determination threshold value, and a dark block in a defined arbitrary block order. It is characterized in that it is configured to compare the block determination thresholds and select a block for which the cumulative addition value exceeds the bright block determination threshold or falls below the dark block determination threshold as a block to be detected. is there.

In the defective pixel detection device having such a configuration, block selection can be performed in order from the position where the defective pixel is easily noticeable, and the defective pixel generated due to the temporal change of the pixel at the easily noticeable position is selected. It is possible to detect it promptly.

According to an eighth aspect of the present invention, in the defective pixel detecting device for a solid-state image pickup device according to the first aspect, the block selecting means is configured to select a designated arbitrary number of blocks. It is characterized by.

In the defective pixel detection device having such a configuration, if it is desired to shorten the period required for the defective pixel detection process for one frame as a whole, the number of blocks to be selected for each photographing is increased and the defective pixel detection process is performed once. If you want to reduce the time required, reduce the number of blocks selected to
It is possible to appropriately adjust the defective pixel detection processing data amount per time.

According to a ninth aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the first aspect, the storage means has position information of the defective pixel, the number of times the defective pixel is detected as a defect, and the defective pixel. Stores the number of times the block including is selected, and when the storage means is full, the ratio of the number of times that the defective pixel is detected to the number of times when the block including the detected defective pixel is selected is It is characterized in that the area in which the information of the smallest defective pixel is stored is set as an empty area.

In the defective pixel detection device thus constructed, when defective pixel detection is performed in a state where the empty space of the storage means is exhausted while the defective pixel detection is repeated, false detection of a previously detected defective pixel may occur. It is possible to reduce the rate of erroneous detection by discarding information that has a high possibility of being present and storing the newly detected defective pixel information.

According to a tenth aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the first aspect, the defect detection means, when the cumulative addition value of the selected blocks is larger than the bright block determination threshold value, In the pixels in the block, those below the bright defect determination threshold are detected as defective pixels, and when the cumulative addition value of the selected blocks is smaller than the dark block determination threshold, the dark defect determination threshold in the pixel in the block is detected. It is characterized in that it is configured to detect a pixel exceeding the above as a defective pixel.

In the defective pixel detection device thus constructed, the defective pixel is detected only by comparing the pixel value in the block with the threshold value, so that the defective pixel can be detected in a short processing time.

According to an eleventh aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the tenth aspect, the bright defect determination threshold value and the dark defect determination threshold value used in the defect detection means are those of a selected block. It is characterized in that it is variable in proportion to the cumulative addition value.

In the defective pixel detection device thus constructed, the threshold value corresponding to the cumulative addition value of the blocks is used, so that it is possible to reduce erroneous detection of defective pixels and omission of detection.

According to a twelfth aspect of the present invention, in the defective pixel detection device for a solid-state image pickup device according to the first aspect, the defect detection means sets an upper limit on the number of pixels detected as a defect. Is.

In the defective pixel detection device thus configured, it is possible to reduce the number of defective pixels detected in one scene and reduce the scene dependency of the defective pixel detection result.

According to a thirteenth aspect of the present invention, there is provided a solid-state image sensor and an A
In an electronic camera provided with an E mode setting means, a defective pixel is formed by using a cumulative addition means for cumulatively adding image data output from the solid-state image sensor for each arbitrary block, and a cumulative addition value by the cumulative addition means. Block selection means for selecting a block to be detected, defect detection means for detecting a defective pixel in the block using image data included in the selected block, and storage means for storing information on the detected defective pixel A defective pixel is detected based on the image data obtained at the time of exposure for photographing, and a correcting unit that corrects the defective pixel based on the stored information about the defective pixel. To do.

In the electronic camera configured as described above, since defective pixels are detected using image data of a photographed image, a start-up time for detecting defective pixels is not delayed, and a subject dedicated to defective pixel detection is prepared. There is no need to do it. Further, since the block for which the defect is detected by the defect detecting unit is appropriately selected by the block selecting unit, the defect detecting process can be performed in a short time.

According to a fourteenth aspect of the present invention, in the electronic camera according to the thirteenth aspect, the block selecting means preferentially selects a block near the center of the screen when the AE mode by the AE mode setting means is center-weighted photometry. It is characterized by being configured as follows.

Shooting with the AE mode set to center-weighted photometry means that the main subject is in the vicinity of the center. Therefore, in the electronic camera constructed in this way, the defect at the position of the main subject is detected. Pixels can be detected quickly.

According to a fifteenth aspect of the present invention, in the electronic camera according to the thirteenth aspect, the block selection means is configured to dynamically change the number of blocks to be selected according to the processing load related to the photographing processing. It is characterized by that.

In the electronic camera constructed as described above, the processing load related to the photographing process differs depending on the image quality and the photographing mode. Therefore, when the processing load related to the photographing process that changes depending on the photographing conditions is small, one frame If the number of blocks to be selected is increased in order to shorten the period required for defective pixel detection of
It is possible to reduce the number of blocks selected in order to shorten the time required for one processing.

According to a sixteenth aspect of the present invention, in the electronic camera according to the thirteenth aspect, the block selecting means is configured to increase the number of blocks to be selected when the temperature of the solid-state image sensor is high. It is a feature.

In the electronic camera constructed as described above, it is possible to increase the probability of detecting a defective pixel that occurs only when the temperature of the solid-state image sensor is high.

According to a seventeenth aspect of the present invention, in the electronic camera according to the thirteenth aspect, the storage means is configured to store information regarding the detected defective pixel before the defect correction by the correction means. It is a feature.

In the electronic camera thus constructed, the defective pixel information detected from the photographed image data is
Since the image data is stored before the defect correction, the detected defective pixel information can be immediately reflected in the defect correction. Therefore, when a defective pixel is generated due to a change with time in a certain photographing, it can be corrected without being noticed by the user of the electronic camera.

According to a eighteenth aspect of the present invention, in the electronic camera according to the thirteenth aspect, the storage means is configured to store information regarding the detected defective pixel after the defect correction by the correction means. It is what

In the electronic camera configured as described above, when the defective pixel is erroneously detected, the pixel defect information erroneously detected this time is not used for the image data used for the defective pixel detection. Even if the spatial frequency of the image data near the erroneously detected defective pixel is high, the image quality is not damaged by the defect correction.

According to a nineteenth aspect of the present invention, in the electronic camera according to the thirteenth aspect, the storage means stores information relating to the detected defective pixel before or after the defect correction according to the photographing mode or the state of the electronic camera. It is characterized in that it is configured to be stored later.

In the electronic camera constructed as described above, in the long-time exposure mode in which defective pixels are easily conspicuous and in the state where the temperature of the solid-state image pickup element rises, defect correction can be performed after storing defective pixel information, and detection can be performed. It is possible to immediately correct the defective pixel thus formed and obtain a good defect correction result. On the contrary, during normal photographing, it is possible to perform defect correction before storing defective pixel information, and to prevent erroneously detected defective pixel information from being immediately reflected, thereby preventing the defect correction result from being impaired. Become.

According to a twentieth aspect of the invention, in the electronic camera according to the thirteenth aspect, the storage means stores defective pixel information detected in an area different from an area in which the defective pixel information used by the correction means is stored. It is characterized in that it is configured to.

In the electronic camera constructed as described above, it becomes possible to detect the defective pixel and execute the operation of storing the defective pixel information and the defective pixel correction operation in parallel, thereby shortening the recording processing time. It will be possible.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments will be described. FIG. 1 is a block diagram showing a first embodiment of a defective pixel detection device for a solid-state image sensor and an electronic camera according to the present invention. This embodiment mainly corresponds to the invention according to claims 1 to 12. It is a thing. In FIG. 1, 1 is a lens, 2 is a diaphragm, 3 is a solid-state image sensor such as CCD, and 4 is A /
An electric signal obtained by photoelectrically converting the intensity of the light received by the solid-state image sensor 3 through the lens 1 and the diaphragm 2 in the solid-state image sensor 3 into a digital converter by the A / D converter 4. The digitally converted image data is stored in the memory 5, and at the same time, cumulative addition is performed by the cumulative addition unit 6 for each block.

Further, in FIG. 1, 7 is a CPU, which controls the respective parts and performs block selection and defective pixel detection by using the image data and the cumulative addition value stored in the memory 5, and 8 is In the non-volatile memory, information relating to a detected defective pixel, which will be described later, is transferred from the memory 5 and permanently stored in the non-volatile memory 8, and the defective pixel position information detected at the time of factory shipment is also permanently stored. Are remembered. The detected defective pixel position information is read and stored in the memory 5 when a new defective pixel is detected or a defective pixel is corrected. It should be noted that, in FIG. 1, in this embodiment, since the detection processing of the defective pixel is mainly described, the illustration of the recording unit and the like as the electronic camera is omitted.

FIG. 2 is a diagram showing how the image data is divided into a plurality of blocks. A large rectangular area F represents the entire image data, and the entire image data is an N × M block Bij (i = 1, ..., M; j =
1, ..., N).
FIG. 3 is a diagram showing an arrangement mode of pixels in each block Bij. When the solid-state image sensor 3 includes a Bayer array color filter, each pixel value in the block Bij is
The color data has an array as shown in FIG. The cumulative adder 4 for each block calculates the pixel values in the block Bij as R, Gr.
, Gb, B are cumulatively added for each color. Position (i, j)
The cumulative addition values of R, Gr, Gb, and B in the block of are defined as σ _Rij , σ _Grij , σ _Gbij , and σ _Bij . The cumulative addition values σ _Rij , σ _Grij , σ _Gbij , σ _Bij are stored in the memory 5 similarly to the image data. The division of the image data into a plurality of blocks is executed simultaneously with the cumulative addition for each block.

Here, the case where the solid-state image pickup device 3 is provided with the color filter of the Bayer array is shown, but when the solid-state image pickup device is provided with the color filter of the complementary color mosaic array, the pixel values in the block are shown. Is Mg,
Cumulative addition is performed for each color of G, Ye, and Cy.

Using the image data stored in the memory 5 and the cumulative addition values σ _Rij , σ _Grij , σ _Gbij and σ _{Bi j} , the CPU
7 performs block selection and defective pixel detection. FIG. 4 shows C
6 is a flowchart for explaining a block selection operation performed by PU7. The block selection is a process of determining a block in which defective pixel detection is to be performed, among N × M blocks Bij. First, the CPU 7 searches for a block based on the cumulative addition values σ _Rij , σ _Grij , σ _Gbij , and σ _Bij according to the block search order table and the block search order table pointer (step S1). The block search order table is a table that stores the order in which N × M blocks are searched, and the block search order table pointer is a table that stores up to what number the block search order table is searched.

The block search is a cumulative addition value σ _Rij ,
σ _Grij , σ _Gbij , σ _Bij are bright block determination thresholds Θ _HR , Θ
_HGr , Θ _HGb , Θ _HB and dark block judgment thresholds Θ _LR , Θ
_{Compared with LGr} , Θ _LGb , Θ _LB , if it is larger than the bright block determination thresholds Θ _HR , Θ _HGr , Θ _HGb , Θ _HB , it is determined as a bright block, and the dark block determination thresholds Θ _LR , Θ _LGr , Θ
If it is smaller than _LGb and Θ _LB , it is a process of determining a dark block and selecting it (step S2). The position of the block determined to be the bright block or the dark block is stored, and at the same time, the number of times the block is selected is updated and stored (step S3). Next, it is determined whether or not the number of blocks determined to be bright blocks or dark blocks has reached a predetermined processing block number L (step S
4) The block search is continued according to the block search order table until the number of processed blocks L is reached. In addition,
The predetermined processing block number L is appropriately determined in consideration of the defective pixel detection processing time.

That is, if it is determined in step S4 that the number of selectively stored blocks has not reached the predetermined number L of processed blocks, the block search order table pointer is updated (step S5), and then the block search order is reached. It is determined whether or not the search has been performed to the end of the table (step S6). If the search has not been performed to the end of the block search order table, step S
Returning to 1, the next block search is performed. On the other hand, when the search is performed up to the end of the block search order table, the block search order table pointer is returned to the head (step S7), and then it is determined whether or not the search of all blocks is completed (step S7). S8) If the search for all blocks has not been completed, the process returns to step S1 and the next block search is performed. On the other hand, when the search for all blocks has been completed, the block search process is completed. In this way, the defective pixel detection processing is performed on all the blocks less than L or the selected L blocks.

FIG. 5 is a flow chart for explaining the defective pixel detection processing operation. First, the selected block position selected and stored by the block selection process is read (step S11), and it is determined whether the read selected block is a bright block or a dark block (step S12). Next, CPU7
Is the pixel value and bright defect determination thresholds θ _HR , θ _HGr , and θ for all pixels in the block determined to be a bright block.
_HGb and θ _HB are compared (step S13), and a pixel whose pixel value is below the bright defect determination thresholds θ _HR , θ _HGr , θ _HGb , and θ _HB is determined to be a defective pixel (step S14) and already stored. Move to the step of comparing the defective pixel. However, the bright defect determination thresholds θ _HR , θ _HGr , θ _HGb , θ
_HB uses a threshold value corresponding to the color of the pixel. The pixel color is R
Θ _HR for Gr, θ _{HGr for} Gr, θ for Gb
_{For HGb} and B, use θ _HB .

With respect to the pixel judged to be a defective pixel in the above step S14, it is judged whether or not it is already stored as a defective pixel (step S15). The number of times the pixel is detected as a defective pixel is updated (step S1)
6). If it is a newly detected defective pixel, it is determined whether or not there is a memory space (step S17). If there is a memory space, the pixel position of the newly detected defective pixel is stored and at the same time The number of times the pixel is detected as a defective pixel is also stored (step S18).

The pixel position of the newly detected defective pixel is recorded.
If there is no memory area to remember, all stored defects
Reference value R for a pixel₁(= Detected as defective pixel
Number of times / the number of times the block containing the defective pixel is selected
The minimum value of (number) is calculated (step S19). Also the same
, The reference value R for the newly detected defective pixel
₂(= Number of times detected as defective pixel /
Calculate the number of times the block
S20), reference value R₁Minimum value and reference value R₂Compare (
Step S21), reference value R₁Is the reference value R₂Less than
If yes, reference value R ₁The minimum defective pixel information of
Erase from memory area (step S22)
Location of the newly detected defective pixel and
The number of times it has been stored is stored (step S18). However, detected
Reference value R of defective pixel₂Is the reference value of the stored defective pixel
R₁If it is smaller than the minimum value of, the defective pixel information memory
From the newly detected defective pixel information without erasing
Discard. By storing defective pixel information in this way,
Therefore, defective pixels that are erroneously detected or disappeared due to aging
As a result, the false detection rate of defective pixels is low.
The effect is to reduce.

Next, as described above, it is determined whether or not the number of defective pixels detected in the same block in the same image data exceeds a predetermined number K (step S23), and the number of detected defective pixels is K. If it does not exceed, then it is determined whether or not defect detection has been performed for all pixels in the same block (step S24). If defect detection has not been performed for all pixels, the same process is performed from step S12 on the next pixel. The predetermined number K may be set to be sufficiently smaller than the length of the shortest line segment that divides the block (that is, the vertical or horizontal size of the block).

Further, in the judgment of step S23,
If the number of defective pixels detected in the same block exceeds K, the defective pixel detection processing for that block is completed and selected even if comparison with the threshold value is not completed for all pixels. The process moves to the determination step (step S25) as to whether or not the defect detection processing has been performed on all blocks. Also, in the determination of step S24, even if the defect detection is performed for all the pixels in the block, the process proceeds to the determination step S25 of whether or not the defect detection processing is performed for all the similarly selected blocks, and the step S25 is performed. If the defect detection processing has not been performed for all blocks in the determination of, the same processing is performed from step S11 on the next block,
If the defect detection processing has been performed for all blocks, the defect detection processing operation ends.

On the other hand, in the step S12 of determining whether the read selected block is a bright block or a dark block, with respect to the block determined to be the dark block, all pixels of the block determined to be the dark block are The pixel value and the dark defect determination thresholds θ _LR , θ _LGr , θ
_LGb and θ _LB are compared (step S26), and a pixel whose pixel value exceeds the dark defect determination thresholds θ _LR , θ _LGr , θ _LGb , and θ _LB is determined to be a defective pixel (step S27). However, the dark defect determination thresholds θ _LR , θ _LGr , θ _LGb , θ
_LB uses a threshold value corresponding to the pixel color. The pixel color is R
Θ _LR in the case of, θ _LGr in the case of Gr, and θ in the case of Gb
_In the case of _LGb and B, θ _LB is used. The process for the pixel determined as the defective pixel is the same as that for the bright block.

As described above, the defective pixel detecting device according to the present embodiment does not require complicated calculation and detects defective pixels only by comparing the threshold value and the data. Therefore, the load on the CPU 7 is extremely small.

FIG. 6 is a block diagram showing a second embodiment of a defect detecting device for a solid-state image pickup device and an electronic camera according to the present invention. This embodiment mainly describes claims 13 to 20.
It corresponds to the invention according to. In FIG. 6, 11 is a lens, 12 is a diaphragm, 13 is a solid-state image sensor, and 14 is an A / D converter.
The electric signal obtained by photoelectrically converting the intensity of the light received by the solid-state image sensor 13 is digitally converted by the A / D converter 14, and the digitally converted image data is stored in the memory 16. On the other hand, with the switch 21, the image quality, A
E mode, operation mode, etc. can be set, and the CPU can be set according to the set image quality, AE mode, operation mode, etc.
Reference numeral 17 determines the compression rate, AE algorithm, etc. when recording the image data stored in the memory 16, records the image data in the recording unit 19, and displays the image data recorded in the recording unit 19 on the liquid crystal display. The display on the device 20 is performed.

When recording is performed, the electric signal obtained by photoelectric conversion in the solid-state image pickup device 13 is A / D as described above.
The image data that has been digitally converted by the converter 14 and that has been digitally converted is stored in the memory 16. Then, similar to the first embodiment shown in FIG. 1, the defective pixel detection process using the cumulative addition value by the cumulative addition unit 15 for each block is performed on the image data stored in the memory 16. Then, based on the defective pixel information stored in the memory 16, defective pixel interpolation processing is performed. The CPU 17 and the logic 22 are used to perform image processing and compression processing on the image data on which the above processing is completed, and the data subjected to the compression processing is stored in the recording unit 19.

In the defective pixel detection in this embodiment,
This is done as follows. That is, first, when the power of the electronic camera is turned on, the CPU 17 determines, from the nonvolatile memory 18, the defective pixel position, the number of times the pixel at the position is detected as a defective pixel, and the number of times each block is detected as a block for performing defective pixel detection processing. Read and store in memory 16. Further, defective pixel detection is performed by the method described in the first embodiment for each image capturing. The detected defective pixel information, that is, the defective pixel position, the number of times the pixel at that position is detected as a defective pixel, and the number of times each block is detected as a block for performing the defective pixel detection process are stored in the CPU 17 when the electronic camera is powered off.
Is read from the memory 16 and stored in the nonvolatile memory 18.

The specific defective pixel detecting method in this embodiment is almost the same as that in the first embodiment, except that the block search order table and the block search order table pointer are handled and the number L of processed blocks is set. But the first
Different from the embodiment.

When the AE mode of the electronic camera is the center-weighted photometry, the block search order table and the block search order table pointer used are different from usual ones. That is, as the block search order table, one set to search for blocks from the center of the screen toward the peripheral is used. The block search order table pointer is normally initialized when the end of the block search order table is searched, but when the AE mode is center-weighted photometry, the block search order table pointer is initialized for each shooting. As a result, when the AE mode is center-weighted photometry, it is possible to always detect defective pixels near the center, that is, near the main subject.

Further, as the number of processing blocks L for each image pickup increases, the number of image pickups required to perform the defective pixel detection for one screen decreases, but the defective pixel detection processing time required for one image pickup increases. . On the other hand, when the image quality set by the switch 21 is high image quality, the time required for the recording process is long, and conversely, when the image quality is low, the time required for the recording process is short. If the defective pixel detection processing time is sufficiently short with respect to the recording processing time, the increase in the recording processing time due to the defective pixel detection processing is not noticeable. Therefore,
The number L of processing blocks is dynamically determined so that the ratio of the defective pixel detection processing time to the recording processing time is sufficiently small and is constant regardless of the image quality. As a result, the defective pixel detection process can be performed with the optimum number of processing blocks L.

Further, when the temperature of the solid-state image pickup device 13 is high, the number of processing blocks L (parameter) is determined by allowing the ratio of the defective pixel detection processing time to the recording processing time to be somewhat large. If the temperature of the solid-state image sensor 13 is high, defective pixels are likely to occur. In the second embodiment, the defect correction process is performed after the defective pixel is detected. Therefore, the defective pixel detected by the defective pixel detection process is immediately corrected. Therefore, the solid-state image sensor 13
If the temperature is high, defective pixels are likely to occur, but by increasing the number L of processing blocks above the normal level, the range in which defective pixel detection is performed can be expanded. Since the defective pixel detected here is immediately corrected, the user of the electronic camera can always obtain a good image regardless of the temperature of the solid-state image sensor 13.

In the second embodiment, since the defect correction processing is performed after the defective pixel is detected, the defective pixel detected by the defective pixel detection is immediately corrected, but the defect detected by the defective pixel detection is corrected. The pixel information may be stored in the memory 16 as new defective pixel information after the defect correction processing, instead of being used in the defect correction processing of the photographing. In the case of such a configuration, even if a white spot or a black spot, which is data, is erroneously detected as a defective pixel, the defective pixel detection result is not reflected in the defect correction processing of the photographing, and therefore does not adversely affect the image. Further, after the next photographing, it is extremely rare that a white spot or a black spot, which is data, is located at an erroneously detected position, so that the image is not adversely affected. Therefore, by storing the detected pixel defect information in the memory 16 after the imaging defect correction processing, it is possible to minimize the influence of erroneous detection.

In the second embodiment, the memory
When 16 is divided into an area in which defective pixel information used in the defect correction processing is stored and an area in which defective pixel information detected by the CPU 17 is stored, the defective pixel detection processing and the defect correction processing are operated in parallel to perform imaging. The processing time can be shortened.

In the second embodiment, an XY address selectable CMOS type image pickup device for picking up a subject image is provided separately from the solid-state image pickup device 13, and the output of this CMOS type image pickup device is arranged for each column. Alternatively, the cumulative addition for each block may be performed by performing cumulative addition for each row. As described above, when the cumulative addition unit for each block 15 is composed of the CMOS type image pickup device, the data flow from the A / D converter 14 to the cumulative addition unit for each block 15 is unnecessary. Further, since the CMOS type image pickup device forming the cumulative addition unit for each block 15 has a lower resolution than the solid-state image pickup device 13, it is possible to perform the cumulative addition process for each block in a short time, and as a result, the defective pixel detection. The time required for processing can be shortened.

[0071]

As described above with reference to the embodiments, according to the invention according to claims 1 to 12, image data is cumulatively added for each arbitrary block, and the defective pixel is used by using the cumulative addition value. Since the block to be detected is selected and the defective pixel detection processing is performed on the selected block, it is possible to detect the defective pixel with high accuracy in a short time with a relatively simple structure. It is possible to realize a defective pixel detection device for a solid-state image sensor. Further, according to the invention according to claims 13 to 20, since it is configured to change the parameter used for the defective pixel detection processing according to the operation mode of the electronic camera and the temperature of the solid-state imaging device, it is efficient. An electronic camera capable of detecting defective pixels can be realized.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a first embodiment of a defective pixel detection device for a solid-state image sensor and an electronic camera according to the present invention.

FIG. 2 is a diagram showing a state in which image data is divided into blocks.

FIG. 3 is a diagram showing a relationship between each pixel in a block and a color when the solid-state imaging device includes a Bayer array color filter.

FIG. 4 is a flowchart for explaining a block selecting operation in the first embodiment shown in FIG.

FIG. 5 is a flowchart for explaining a defective pixel detection processing operation in the first embodiment shown in FIG.

FIG. 6 is a schematic block diagram showing a second embodiment of a defective pixel detection device for a solid-state image sensor and an electronic camera according to the present invention.

[Explanation of symbols]

1 lens 2 aperture 3 Solid-state image sensor 4 A / D converter 5 memory Cumulative addition unit for every 6 blocks 7 CPU 8 Non-volatile memory 11 lens 12 aperture 13 Solid-state image sensor 14 A / D converter 15-block cumulative addition unit 16 memory 17 CPU 18 Non-volatile memory 19 Recording section 20 Liquid crystal display 21 switch 22 logic

Claims (20)

[Claims] 1. A block for selecting a block for defective pixel detection using a cumulative addition means for cumulatively adding image data output from a solid-state image sensor for each arbitrary block, and a cumulative addition value by the cumulative addition means. A solid-state device comprising: a selection unit, a defect detection unit that detects a defective pixel in the block using image data included in the selected block, and a storage unit that stores information about the detected defective pixel. Defective pixel detection device for image sensor. 2. The storage means is divided into an area for storing defective pixel position information detected at the time of factory shipment and an area for storing information on defective pixels detected after factory shipment, which are detected at the time of factory shipment. The defective pixel detection device for a solid-state image sensor according to claim 1, wherein the defective pixel position information is configured not to be updated. 3. The cumulative addition means is configured to calculate a cumulative addition value for each color when the solid-state imaging device includes a Bayer array color filter. A defective pixel detection device for such a solid-state image sensor. 4. The cumulative addition means, when the solid-state image sensor includes a complementary color mosaic array color filter,
The defective pixel detection device for a solid-state image pickup device according to claim 1, wherein the cumulative addition value is calculated for each color. 5. The solid-state device according to claim 1, wherein the cumulative addition means is composed of a CMOS image sensor, and is configured to perform cumulative addition for each column and each row of the CMOS image sensor output. Defective pixel detection device for image sensor. 6. The block selection means compares the cumulative addition value with a bright block determination threshold value and a dark block determination threshold value,
The solid-state image pickup device according to claim 1, wherein when the cumulative addition value is larger than the bright block determination threshold or smaller than the dark block determination threshold, the block is selected as a block to be subjected to defective pixel detection processing. Defective pixel detection device. 7. The block selection means compares the cumulative addition value with the bright block determination threshold value and the dark block determination threshold value in a defined arbitrary block order, and the cumulative addition value exceeds the bright block determination threshold value or the dark block determination threshold value. The defective pixel detection device for a solid-state image pickup device according to claim 1, wherein a block that has fallen below a determination threshold is configured to be selected as a block for which detection processing is performed. 8. The defective pixel detection device for a solid-state image pickup device according to claim 1, wherein the block selection means is configured to select a designated arbitrary number of blocks. 9. The storage means stores position information of defective pixels,
The number of times that the defective pixel is detected as a defect and the number of times that a block including the defective pixel is selected are stored, and when the storage means is full, it is detected as the number of times that the defective pixel is detected. 2. An area in which information of a defective pixel having the smallest ratio of the number of times a block including the defective pixel is selected is set as an empty area.
Of solid-state image sensor according to claim 1. 10. The defect detection means, when the cumulative addition value of the selected block is larger than the bright block determination threshold value, detects pixels in the block that are below the bright defect determination threshold value as defective pixels, If the cumulative addition value of the selected block is smaller than the dark block determination threshold,
The defective pixel detection device for a solid-state image sensor according to claim 1, wherein pixels in the block that exceed a dark defect determination threshold are detected as defective pixels. 11. The solid according to claim 10, wherein the bright defect determination threshold and the dark defect determination threshold used in the defect detecting unit are variable in proportion to the cumulative addition value of the selected blocks. Defective pixel detection device for image sensor. 12. The defective pixel detection device for a solid-state image sensor according to claim 1, wherein the defect detection unit sets an upper limit on the number of pixels detected as a defect. 13. An electronic camera comprising a solid-state image sensor and an AE mode setting means, a cumulative addition means for cumulatively adding image data output from the solid-state image sensor for each arbitrary block, and the cumulative addition means. Block selecting means for selecting a block in which defective pixel detection is performed using the cumulative addition value, defect detecting means for detecting defective pixel in the block using image data included in the selected block, and detected defect A storage unit that stores information about a pixel and a correction unit that corrects the defective pixel based on the stored information about the defective pixel are provided, and the defective pixel is detected from the image data obtained at the exposure for photographing. An electronic camera characterized by being configured in. 14. The block selection means is configured to preferentially select a block near the center of the screen when the AE mode set by the AE mode setting means is center-weighted photometry. The electronic camera concerned. 15. The block selection unit is configured to dynamically change the number of blocks to be selected according to a processing load related to a shooting process.
Electronic camera according to. 16. The electronic camera according to claim 13, wherein the block selection unit is configured to increase the number of blocks to be selected when the temperature of the solid-state image sensor is high. 17. The electronic camera according to claim 13, wherein the storage unit is configured to store information regarding the detected defective pixel before the defect correction by the correction unit. 18. The electronic camera according to claim 13, wherein the storage unit is configured to store information regarding the detected defective pixel after the defect correction by the correction unit. 19. The storage unit is configured to store information regarding a detected defective pixel before or after defect correction according to a shooting mode or a state of an electronic camera. An electronic camera according to item 13. 20. The storage means is configured to store the detected defective pixel information in an area different from the area in which the defective pixel information used by the correction means is stored. Electronic camera according to 13.