JP2001111899A - Image pickup device and its deteriorated pixel signal correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device that can obtain an image with high image quality in which smear is reduced and an unnatural false signal is reduced or eliminated by applying data compensation to pixels that cannot be coped with simple smear correction and to provide its deteriorated pixel signal correction method. SOLUTION: This image pickup device is composed of a CCD image pickup element 5, a smear detection section 8-1 that detects a smear component from the CCD image pickup element, a smear correction section 8-5 that corrects the valid image pickup signal on the basis of the detected smear component, an output deteriorated pixel decision section 8-2 that decides a valid signal pixel to be an output deteriorated pixel when the level of the smear component exceeds a prescribed value, a compensation condition decision section 8-3 that decides whether or not the output deteriorated pixel satisfies a prescribed compensation condition, and a data compensation section 8-4 that compensates data of the pixel decided to satisfy the compensation condition by using adjacent pixel information. A smear correction section corrects pixels not satisfying the compensation condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image pickup apparatus, and more particularly to an image pickup apparatus having a function of correcting a pseudo signal and a method of correcting a deteriorated pixel signal.

[0002]

2. Description of the Related Art In a solid-state image pickup device using a CCD image pickup device, as a phenomenon peculiar to the CCD image pickup device, there is a problem of image quality deterioration due to a smear phenomenon generated when intense light enters. That is, this phenomenon is due to the fact that the charge not captured in the original charge storage region leaks into the vertical transfer path through the potential barrier. If this is caused by normal stationary light, this phenomenon occurs over the vertical transfer period.For example, in the case of spot light, vertical streaks that extend up and down the spot light, for example, a high brightness portion such as a landscape including the sky Is an object that spreads in the horizontal direction, a white image in which the entire screen is flared is obtained.

[0003] As a method of correcting this, paying attention to the fact that smears are generated at substantially the same level in the vertical direction from the principle of generation thereof, a vertical OB (optical black: optical black: (Optical black) A method of using the output level of a pixel as a smear removal reference signal and subtracting this from the pixel output signal of the effective screen is disclosed in, for example,
No. 67038 discloses a known method.

[0004]

By the way, if the smear correction is simply adopted by using the above-mentioned conventional technology, the output range of an image pickup device used in a real camera is limited, so that the smear component is reduced. If it is large, there is a problem that the image quality is deteriorated by the correction. Explaining this with a specific example, the vertical streak-like smear caused by the strong spot light reaches the saturation level of the image sensor (100%).
%), The output signal of the image sensor in a portion without smear is output as it is even after smear correction, but in the smear portion, the output of the image sensor is 1 due to saturation of the image sensor.
The output after smear correction (element output-
(Smear component) becomes zero. Therefore, a vertical black streak is generated. Alternatively, if the spot light portion itself is viewed as a subject at this time, this portion also has an output of 0.

[0005] Such a phenomenon that a vertically extending black streak or a subject which is supposed to have extremely high brightness is crushed black causes an extremely unnatural and strange image. Even if a normal subject having a small smear level can be imaged with higher image quality than before, image quality degradation (failed image) that is unacceptable for an imaging device targeting various subject scenes occurs. Therefore, the conventional smear correction method has a problem that it is difficult to adopt it.

In other words, when the smear has reached near the saturation level, almost no luminance information of the subject can be obtained, so the conventional correction is meaningless, or rather, a new false signal is generated. On the contrary, it was harmful and would be in a state of no interest. Alternatively, it has been difficult to obtain at least unnatural image quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional smear correction method, and it is intended to prevent at least the occurrence of unnatural image quality which would cause a failure and to reduce the smear caused by smear. It is an object of the present invention to provide an image pickup apparatus capable of performing effective smear correction with substantially improved image quality as compared with the related art, and a method of correcting a deteriorated pixel signal of a part in which luminance information of a subject cannot be obtained at all. I do.

Further, according to the present invention, it is possible to make a determination based on the level of a smear component and apply data compensation to a deteriorated pixel which cannot be dealt with by the conventional smear correction due to signal saturation or the like. An object of the present invention is to provide an imaging device and a method for correcting a deteriorated pixel signal thereof. The present invention also provides
Performs higher-level judgment considering both the smear component level and the effective signal pixel output level, and applies data compensation to pixels that cannot be handled by conventional corrections due to signal saturation etc. It is an object of the present invention to provide a simple imaging device and a method of correcting a deteriorated pixel signal thereof. It is another object of the present invention to provide an imaging apparatus and a method of correcting a deteriorated pixel signal, which does not cause generation of an unnatural image due to unlimited compensation. Another object of the present invention is to provide an image pickup apparatus capable of obtaining an image in which an unnaturally conspicuous false signal inevitable in principle typified by a white streak is reduced or eliminated, and a method of correcting a deteriorated pixel signal thereof. And Another object of the present invention is to provide an imaging apparatus capable of obtaining an overall high-quality image in which smear is reduced and an unnaturally conspicuous false signal is reduced or eliminated, and a method of correcting a deteriorated pixel signal thereof. I do.

[0009]

According to a first aspect of the present invention, there is provided a smear detecting apparatus for detecting a smear component of an image sensor based on an image sensor output corresponding to a vertical blanking period. Means, when the level of the smear component detected by the smear detection means exceeds a predetermined value,
An image pickup apparatus is constituted by output deterioration pixel determination means for determining a corresponding effective signal pixel as an output deterioration pixel. In the imaging device configured as described above, when the level of the smear component exceeds a predetermined value, the corresponding effective signal pixel is determined to be an output degraded pixel. It becomes possible to apply data compensation to pixels that cannot be dealt with by the conventional correction that is caused, and it is possible to make a determination at this time only with the level of the smear component.

According to a second aspect of the present invention, there is provided a smear detecting means for detecting a smear component of the image sensor based on an output of the image sensor corresponding to a vertical blanking period, and a level of the smear component detected by the smear detecting means. When the output signal exceeds a predetermined value, and the output level of the corresponding effective signal pixel has reached a predetermined saturation level, the imaging device is constituted by output deterioration pixel determination means for determining this as an output deterioration pixel. Things. In the imaging device configured as described above, when the level of the smear component exceeds a predetermined value, if the output level of the corresponding effective signal pixel has reached a predetermined saturation level, the level of the output deterioration is reduced. Since the pixel is determined to be a pixel, it is possible to apply data compensation to a pixel that cannot be handled by the conventional correction due to signal saturation or the like. It is possible to perform a more advanced determination in consideration of both the output levels of the effective signal pixels.

According to a third aspect of the present invention, in the image pickup apparatus according to the first or second aspect, there is provided a compensation condition determining means for determining whether or not the output deteriorated pixel satisfies a predetermined compensation condition. It is a feature. Since the imaging apparatus configured as described above includes the compensation condition determination unit that determines whether or not a predetermined compensation condition is satisfied for the output deteriorated pixel, an unnatural image accompanying unlimited compensation is provided. Can be prevented from being generated.

According to a fourth aspect of the present invention, there is provided a smear level detecting means for detecting a smear level generated in an effective pixel of an image sensor based on a signal output from a light-shielded pixel column of the image sensor during a vertical blanking period. When the smear level detected by the smear level detecting means exceeds a predetermined value, a deteriorated pixel determining means for determining a corresponding effective signal pixel as an output deteriorated pixel, and an output deteriorated pixel by the deteriorated pixel determining means. When a signal from the determined pixel has reached a predetermined saturation level, a compensation condition determining unit that determines whether a predetermined compensation condition is satisfied for the deteriorated pixel, and a compensation condition determined by the compensation condition determination unit. An image pickup apparatus is configured by a deteriorated pixel correction unit that replaces a signal from a deteriorated pixel determined to be satisfied with a non-degraded pixel signal near the deteriorated pixel. .

[0013] The imaging apparatus thus configured includes a smear level detecting means and a deteriorated pixel judging means, and when the detected smear level exceeds a predetermined value,
Since the corresponding effective pixel is determined to be an output degraded pixel, it is possible to apply data compensation to a pixel that cannot be handled by the conventional correction due to signal saturation or the like. The determination at this time can be made only at the smear level. In addition, since a compensation condition determination unit that determines whether or not a predetermined compensation condition is satisfied for the output-deteriorated pixel is provided, it is possible to prevent the possibility of generating an unnatural image due to unlimited compensation. .
In addition, since a deteriorated pixel correction unit having the above-described configuration is provided, for a deteriorated pixel that is determined to satisfy a predetermined condition, data compensation is performed based on a nearby non-deteriorated pixel signal, and a representative image is represented by white streaks. Thus, an image can be obtained in which unnaturally conspicuous false signals which cannot be avoided in principle are reduced or eliminated.

According to a fifth aspect of the present invention, in the image pickup apparatus according to the fourth aspect, the deteriorated pixel correcting means performs the smear level correction on a signal from a deteriorated pixel determined not to satisfy the compensation condition. The output level is corrected in accordance with the smear level detected by the detection means. As described above, in the imaging device according to claim 5, the output level of the deteriorated pixel that does not satisfy the predetermined condition is corrected according to the smear level.
It is possible to obtain a higher-quality image in which smear is reduced and unnaturally conspicuous false signals are reduced or removed.

In the imaging apparatus according to the fourth or fifth aspect, as described in the sixth aspect, the smear level of the imaging element detected by the smear level detecting means is determined from the light-shielded pixel row of the same horizontal address. It is preferable to form the sum of the signal levels by dividing the sum by the total number of pixels in the same light-shielded pixel column. In the imaging device according to the fourth or fifth aspect, as in the seventh aspect, the predetermined compensation condition is that at least one of four neighboring pixel rows having the degraded pixel row at the center. It is preferable that the condition that the non-deteriorated pixel column is included is included. In the image pickup apparatus according to the fifth aspect, as described in the eighth aspect, the correction of the output level according to the smear level performed by the deteriorated pixel correction unit is performed by subtracting the detected smear level from the deteriorated pixel level. , A correction based on a coefficient based on the saturation level and the detected smear level.

According to a ninth aspect of the present invention, a step of detecting a smear component of the image sensor based on an output of the image sensor corresponding to a vertical blanking period, and a level of the smear component detected in the smear component detection step When a value exceeds a predetermined value, a method of correcting a deteriorated pixel signal of the imaging apparatus is configured by an output deteriorated pixel determination step of determining a corresponding effective signal pixel as an output deteriorated pixel.

The method of correcting a deteriorated pixel signal of the imaging apparatus having the above-described configuration includes a smear component detection step and a deteriorated pixel determination step, and when the level of the detected smear component exceeds a predetermined value, the step is performed. Since the corresponding effective pixel is determined to be an output degraded pixel, it is possible to apply data compensation to a pixel that cannot be handled by conventional correction due to signal saturation or the like, and The determination at this time can be made only at the smear level.

The invention according to claim 10 is a step of detecting a smear component of the image sensor based on an output of the image sensor corresponding to a vertical blanking period, and a level of the smear component detected in the smear component detection step. When the output level of the effective signal pixel corresponding to this exceeds a predetermined value, the output deterioration pixel determination step of determining this as an output deterioration pixel when the output level of the corresponding effective signal pixel has reached a predetermined saturation level. This constitutes a signal correction method.

The method of correcting a deteriorated pixel signal of the image pickup apparatus having the above-described configuration includes a smear component detection step and a deteriorated pixel determination step. When the smear component level exceeds a predetermined value, the method is performed. When the output level of the effective pixel reaches a predetermined saturation level, the pixel is determined to be an output degraded pixel. In this case, data compensation can be applied, and at this time, it is possible to perform a higher-level determination in consideration of both the level of the smear component and the output level of the effective signal pixel.

According to an eleventh aspect of the present invention, in the method for correcting a deteriorated pixel signal of the image pickup apparatus according to the ninth or tenth aspect, a compensation condition determining step of determining whether a predetermined compensation condition is satisfied for the output deteriorated pixel is provided. It is characterized by having. In the method of correcting a deteriorated pixel signal of the imaging apparatus configured as described above, the method includes a compensation condition determination step of determining whether a predetermined compensation condition is satisfied for the output deteriorated pixel. Can be prevented from generating an unnatural image.

According to a twelfth aspect of the present invention, there is provided a method for detecting a smear level generated in an effective pixel of an image sensor based on a signal output from a light-shielded pixel column of the image sensor during a vertical blanking period; When the smear level detected in the smear level detection step exceeds a predetermined value, a step of determining a valid pixel corresponding to the smear level as an output deteriorated pixel, and a signal from a pixel determined as an output deteriorated pixel in the deteriorated pixel determination step. Determining whether or not a predetermined compensation condition is satisfied for the deteriorated pixel when a predetermined saturation level is reached, and a signal from the deteriorated pixel determined to satisfy the compensation condition in the compensation condition determination step. Is replaced by a non-deteriorated pixel signal in the vicinity of the degraded pixel. And it constitutes.

The method of correcting a deteriorated pixel signal of the image pickup apparatus having the above-described configuration includes a smear level detecting step and a deteriorated pixel determining step, and corresponds to a case where the detected smear level exceeds a predetermined value. Since an effective pixel is determined to be an output-deteriorated pixel, it is possible to apply data compensation to a pixel that cannot be handled by the conventional correction due to signal saturation or the like. Can be determined only at the smear level. In addition, since it has a compensation condition determination step of determining whether a predetermined compensation condition is satisfied for the output deteriorated pixel,
It is possible to prevent the risk of generating an unnatural image due to unlimited compensation. In addition, since the image processing apparatus has the deteriorated pixel correction step having the above configuration, data compensation is performed on a deteriorated pixel determined to satisfy the predetermined condition based on a nearby non-deteriorated pixel signal, and is represented by a white streak. It is possible to obtain an image in which an unnatural and conspicuous false signal which cannot be avoided in principle is reduced or eliminated.

According to a thirteenth aspect of the present invention, in the method for correcting a deteriorated pixel signal of the image pickup apparatus according to the twelfth aspect, the deteriorating pixel correction step is performed on a signal from the deteriorating pixel determined not to satisfy the compensation condition. Preferably, the method further comprises the step of correcting an output level according to the smear level detected in the smear level detecting step. As described above, in the deteriorated pixel signal correction method according to the thirteenth aspect, the output level is corrected according to the smear level for the deteriorated pixel that does not satisfy the predetermined condition, so that the smear is reduced in consideration of the smear level. It is possible to obtain a higher quality image in which the unnatural and conspicuous false signals are reduced or eliminated.

In the method of correcting a deteriorated pixel signal of an image pickup apparatus according to claim 12 or 13, the smear level of the image sensor detected in the smear level detecting step is the same as that of the same horizontal address. It is preferable that the sum of the signal levels from the light-shielded pixel column is divided by the total number of pixels in the same light-shielded pixel column. Further, in the method of correcting a deteriorated pixel signal of an imaging device according to claim 12 or 13, as set forth in claim 15, the predetermined compensation condition is such that a neighboring pixel row 4 having the deteriorated pixel row as a center is used. Preferably, the condition is that at least one non-deteriorated pixel column is included in the column. Further, in the method of correcting a deteriorated pixel signal of the imaging apparatus according to claim 13, as in claim 16, the correction of the output level according to the smear level in the deteriorated pixel correction step includes detecting the smear from the deteriorated pixel level. It is preferable to perform the correction by subtracting the level and multiplying by a coefficient based on the saturation level and the detected smear level.

[0025]

Next, an embodiment will be described. FIG. 1 is a block diagram showing a digital video camera according to a first embodiment of the imaging apparatus according to the present invention. In FIG. 1, 1 is a lens system, 2 is a lens driving mechanism, 3 is an exposure control mechanism, 4 is a filter system, 5 is a CCD image sensor, 6 is a CCD driver, 7 is a pre-processing circuit including an A / D converter, 8 Is a digital process circuit that includes a memory as hardware and performs all digital process processing. 9 is a recording unit (VTR block), 10 is a video tape, 11 is an LCD image display system, 12 is a system controller including a microcomputer as a main configuration, 13 is an operation switch system, 14 is an operation display system including a display LCD, 15 Is a lens driver, 16 is an exposure control driver,
17 is an EEPROM.

In the digital video camera constructed as described above, the system controller 12 performs overall control, and includes an exposure control mechanism 3 as an iris diaphragm (iris) and a CCD driver 6 by a CCD driver 6.
By controlling the driving of the image pickup device 5, exposure (charge accumulation) and signal readout are performed at a predetermined moving image rate, and the signals are temporarily stored in the digital process circuit 8 via the preprocess circuit 7, and are stored therein. After performing various signal processing, the signal is sent to the recording unit 9 and recorded on the video tape 10.

The digital process circuit 8 for performing the above-described various signal processing includes a main part of the present invention,
A smear correction process using output level information of a vertical OB pixel is included. That is, the digital process circuit 8
Includes a smear level detector 8-1 for detecting the output level of the vertical OB pixel, an output deteriorated pixel determiner 8-2 for determining an output deteriorated pixel based on a detection output of the smear level detector 8-1, and the like. A compensation condition determination unit 8-3 for determining whether a predetermined compensation condition is satisfied for the deteriorated pixel, a data compensation unit 8-4 for performing data compensation on the deteriorated pixel determined to satisfy the compensation condition, and a smear correction unit 8- (Note that these units 8-1 to 8-5 may not always be clearly separated in actual arithmetic processing, but are separated for convenience of explanation and concept for clarity. Is shown). Of course, all of these processes are so-called real-time processes performed at a speed sufficient to perform recording at the predetermined moving image rate.

Next, camera control by the system controller 12 will be described focusing on processing directly related to smear correction of the present invention. First, when an image pickup output signal corresponding to one screen obtained by sequentially reading out signal charges of the CCD image pickup element 5 generated by the exposure in the above operation is stored in a predetermined memory area of the digital process circuit 8, first, a smear level detection section 8-1 , A smear component is detected using the output of the vertical OB pixel to calculate a smear removal reference signal. In the calculation, the sum of each pixel having the same horizontal address among the data of the OB pixels on a plurality of lines is calculated as necessary, and the average value is obtained by dividing by the number of pixels, as in the prior art described in the above publication. Get. The smear removal reference signal is an image signal for one line, and an average value obtained by the above calculation is used as a value of each pixel signal constituting the image signal for one line. The smear removal reference signal obtained in this way is defined as Sm (i). Where i is the horizontal address,
J described later is a vertical address.

Then, in the output deteriorated pixel judging section 8-2, the compensation condition judging section 8-3, the data compensating section 8-4 and the smear correcting section 8-5, the effective image area is picked up using the smear removing reference signal. A correction process is performed on the output signal Sig (i, j). The smear correction processing of the present invention performs different processing according to the imaging output signal and the level of smear at this time,
Furthermore, among those that cannot be corrected in principle, those that can perform a predetermined compensation process are characterized in that the compensation process is performed using information on neighboring pixels. The saturation level of the image sensor (or a signal processing system receiving the output) is expressed by S
at, predetermined comparison levels are R1 and R2 (0 <R1 <R2
<Sat), assuming that the output after smear correction is Sout (i, j) (of course, 0 ≦ Sm (i) ≦ Sig (i, j) ≦ Sat)
The specific signal processing in the present embodiment is as follows. First, the basic signal processing is represented by the following equation (1). Sout (i, j) = S1 (i, j) {Sig (i, j) -Sm (i)} * Sat / {Sat-Sm (i)} (1)

Here, the specific meaning of the smear correction signal processing of this embodiment will be described. If the conventional processing to be compared is expressed by an equation, it is expressed by the following equation (2). Sout (i, j) = Sig (i, j) -Sm (i) (2) In the case of this conventional processing, the problem of the above conventional technique is particularly easy to understand. Although an example is shown, if this is generalized, the problem is that the range of the output signal becomes smaller, that is, the maximum value of the output signal Sout (i, j) after smear correction becomes smaller by the smear level. , Sat-Sm (i).

In the extreme case, the above-mentioned black streaks are generated. However, if it is not, "when a saturation occurs, ie, Sig (i, j) = Sat", "the smear exists, that is, When "Sm (i)>0", gray to black streaks are generated according to the smear level.
As a result, an extremely unnatural strange image is generated as compared with the white streak at the time of no correction. If these aspects are shown graphically,
The results are as shown in FIGS. FIG. 2A shows the input / output characteristics in the case of no correction, and FIG. 2B shows the input / output characteristics by the conventional processing. From the characteristic shown in FIG. 2B, it can be seen that although only the original signal component is obtained, the maximum value is small.

On the other hand, if Sig (i, j) = Sat is substituted for S1 (i, j) in the above equation (1) in this embodiment, the output Sout (i, j) = Sat becomes can get. In this case, the portion becomes white output at the saturation level due to the influence of smear or the high luminance of the subject itself. However, since it is at least equivalent to the conventional uncorrected image, it is strange like the above-described conventional smear correction. No image is produced.

FIG. 3 shows the conversion (input / output) characteristics corresponding to S1 (i, j) in the equation (1). Comparing the characteristic shown in FIG. 3 with the characteristic shown in FIG. 2B, the characteristic shown in FIG. 3 according to the present embodiment is similar to the characteristic shown in FIG. It can be seen that it approaches the value of the characteristic shown (coincidence when the signal component = 0) and approaches the uncorrected value on the high luminance side (coincides when Sig (i, j) = Sat). When the generation level of smear is relatively small, the smear is easily recognized particularly in a low-luminance subject. Therefore, S1 (i, j) in the expression (1) is used.
The present invention effectively balances the smear correction effect and the elimination of the above-mentioned conventional disadvantageous phenomena.

By performing such smear correction,
Although the disadvantages of the conventional smear correction method are eliminated, it is true that when the output of the image sensor is saturated, white streaks and the like occur as in the conventional case of no correction, In this case, since the subject information cannot be obtained for the saturated pixel, it is basically difficult to do anything in principle. Here, in the present invention, the degradation state of a pixel whose pixel information is degraded due to such smear is determined, and when a predetermined condition is satisfied, the degraded pixel is regarded as a pixel defect. Then, by performing compensation processing using neighboring pixels or the like, the substantial image quality (image quality for appreciation) is further improved even slightly, and this point is extremely characteristic.

Specifically, the predetermined reference level is set to R (≠
0), a deteriorated pixel is determined based on the following deterioration determination criteria (1) to (4). (1) When Sm (i) = Sat (When the smear level reaches saturation: In this case, Sig (i, j) = Sat) In this case, the output has deteriorated due to the influence of smear. Since it is a pixel, it is determined to be a deteriorated pixel. There is no subject information. (2) When Sm (i)> R and Sig (i, j) = Sat In this case, it is highly likely that the output has deteriorated due to the influence of smear. There is no subject information. (3) When Sm (i)> R and Sig (i, j) <Sat In this case, although smear exists at a high level, it is determined that the smear has subject information and is not a deteriorated pixel. (4) Sm (i) ≦ R In this case, it is determined that the pixel is not a deteriorated pixel. (Although a saturated pixel may be affected by smear, it is assumed that the main cause is a high level of the subject itself.)

For a pixel determined to be a deteriorated pixel, a compensation condition determination for determining whether or not a predetermined compensation condition is satisfied is performed. The condition is that the adjacent pixel on either the left or right of the target pixel signal Sig (i, j) is not a deteriorated pixel,
Specifically, the following conditions are set. [Compensation condition: at least one column (non-deteriorated pixel column) that does not include at least one degraded pixel exists in each column of i-2, i-1, i + 1, and i + 2. In other words, the condition is that at least one non-deteriorated pixel column is included in four neighboring pixel columns having the degraded pixel column at the center. Compensation processing is performed on a deteriorated pixel that satisfies the compensation condition. Prior to that, for all pixels (at least for a non-deteriorated pixel and a deteriorated pixel that does not satisfy the compensation condition), the above equation (1) is used. Smear correction by S1 (i, j) is performed. That is, the data after this correction is used in the compensation processing.

Next, the contents of the compensation processing will be specifically described. S
If any of ig (i-1, j) and Sig (i + 1, j) is a non-deteriorated pixel, the pixel information of the non-deteriorated pixel (average value in the case of any non-deteriorated pixel) Otherwise, ie Sig
If both (i-1, j) and Sig (i + 1, j) are deteriorated pixels, the pixel information of either Sig (i-2, j) or Sig (i + 2, j) ( The average value of each of them is non-degraded) and the Sig (i,
j). That is, a compensation process of replacing with a nearby non-deteriorated pixel signal is performed.

That is, since the deteriorated pixel is replaced by information of the non-degraded pixel within at least two neighboring pixels on either the left or right (information reflecting subject information), for example, a white streak caused by smear in the related art Its width can be reduced by a maximum of four pixels. Naturally, if the pixel width is less than 4 pixels, it will disappear by this compensation processing. If such processing is performed indefinitely, for example, over a very large pixel width, an unnatural image will of course occur, but if the processing is limited to only a few pixels, the unnaturalness will be very noticeable. However, it is possible to obtain a great effect of reducing or removing a conspicuous false signal which is a very unnatural white streak.

By the smear correction processing including the above-described compensation processing, the generation of smear at a relatively low level is relatively close to the conventional smear correction (in a low-luminance object portion where smear is conspicuous). Output that is closer to the original subject signal).
The defect caused by signal saturation caused by the conventional correction is greatly reduced, and has a correction characteristic in which an unusual and unnatural pseudo signal such as a broken image quality such as a black streak does not occur. A high-quality smear correction process is performed in which unnatural conspicuous false signals that cannot be avoided in principle such as streaks are reduced or eliminated.

As described above, the output image signal Sout (i, j) subjected to the smear correction processing is recorded on the video tape 10 or displayed on the LCD image display system 11 through various signal processings as appropriate. The image to be recorded or displayed is a high-quality image in which smear is effectively corrected and unnatural spurious signals are not generated.

The digital video camera according to the present embodiment includes a conventionally known pixel defect compensating means which is included in the various signal processings and is different from the compensation processing in the smear correction. For the output signal after the smear correction corresponding to the effective pixel portion, the EEPROM
This processing is performed based on the defective pixel address data stored in 17. At this time, it is meaningful to perform smear correction first and perform defect compensation later. This is for the following reason. That is, since output signals of different horizontal addresses are usually used for defect compensation, if the processing order is simply changed and defect compensation is performed first, smear correction will not be performed correctly and a new false signal will be caused, which is not preferable. It is.

It should be noted that various embodiments other than the above-described embodiment are conceivable. For example, the correction of S1 (i, j) in the equation (1) performed prior to the compensation processing can be performed with any correction characteristic including a conventionally known smear correction. In this case, depending on the correction characteristics employed, there may be cases where it is not always possible to obtain a comprehensively sufficient image quality, but at least the effect of reducing or eliminating a rather unnatural and conspicuous false signal such as a white streak which could not be improved conventionally. Is obtained, and if the correction characteristics employed are better than those of the above-described embodiment, the combined image quality is further improved by the combination.

Apart from this, in the above description, the compensation conditions and compensation processing have been described in a relatively simple manner, but can be applied as long as the image pickup device is monochrome. On the other hand, in the case of a single-chip color imaging device, it may be difficult to apply the above description literally due to the influence of color coding. However, in this case as well, for example, attention should be paid to the minimum unit (which can be called a pixel relating to color) for obtaining color information related to the color coding, and this should be read as one pixel in the above embodiment. By doing so, the present invention can be similarly applied to a color imaging device.

In the above-described embodiment, an output corresponding to a so-called vertical OB pixel is used for smear detection. However, this is an example, and there is no photoelectric conversion element (pixel storage unit) that actually corresponds. However, since the detection of smear can be similarly performed using the image sensor output corresponding to the vertical blanking period, it is obvious that such a known configuration may be used.

Furthermore, in the above-described embodiment, moving pictures are mainly recorded, but signal processing is performed only for one frame of image (intra-frame processing). Of course it can be applied. For example, those which are applied to a still image shooting mode additionally provided by the camera or to a digital still camera mainly for shooting another still image are each a preferred embodiment. Needless to say, the above description is not intended to limit the scope of the present invention to intra-frame processing, and is easily applicable to inter-frame processing.

Although several embodiments of the present invention have been specifically described above, the present invention is not limited to these embodiments, and can take any form as long as it is described in the claims. Needless to say.

[0047]

As described above, according to the present invention, according to the present invention, a smear is reduced by smear correction, and a high-quality image in which an unnatural false signal is reduced or eliminated is obtained. be able to. In particular, according to the first and ninth aspects of the present invention, there is provided a smear component detecting unit and an output deteriorated pixel determining unit, or a smear component detecting step and an output deteriorated pixel determining step, and the detected smear level exceeds a predetermined value. In this case, the effective pixel corresponding to this is determined to be an output degraded pixel, so that data compensation can be applied to a pixel that cannot be handled by conventional correction due to signal saturation or the like. This makes it possible to make the determination at this time only on the smear level.
According to the second and tenth aspects of the present invention, when the level of the smear component exceeds a predetermined value, if the output level of the corresponding effective signal pixel reaches a predetermined saturation level, Since it is configured to judge as an output degraded pixel, it is possible to apply data compensation to pixels that cannot be handled by conventional corrections due to signal saturation, etc. And the output level of the effective signal pixel is considered in a more sophisticated determination. According to the third and eleventh aspects of the present invention, since there is provided a compensation condition determination means or a compensation condition determination step for determining whether or not a predetermined compensation condition is satisfied for an output-deteriorated pixel, compensation can be performed without limitation. Can be prevented from generating an unnatural image.

According to the fourth and twelfth aspects of the invention,
It is provided with a smear level detecting means and a deteriorated pixel determining means or a smear level detecting step and a deteriorated pixel determining step, and when the detected smear level exceeds a predetermined value, an effective pixel corresponding thereto is determined as an output deteriorated pixel. Therefore, it is possible to apply data compensation to pixels that cannot be handled by the conventional correction due to signal saturation or the like, and the determination at this time can be performed only at the smear level. . In addition, since a compensation condition determination unit or a compensation condition determination step for determining whether or not a predetermined compensation condition is satisfied for the output deteriorated pixel is provided, an unnatural image may be generated due to unlimited compensation. Can be prevented. In addition, since a deteriorated pixel correction unit or a deteriorated pixel correction step having the above-described configuration is provided, for a deteriorated pixel determined to satisfy a predetermined condition, data compensation is performed based on a nearby non-deteriorated pixel signal. Thus, an image can be obtained in which unnatural and conspicuous false signals which cannot be avoided in principle, such as white streaks, are reduced or eliminated. According to the fifth and thirteenth aspects of the present invention, for a deteriorated pixel which does not satisfy the predetermined condition, the output level is corrected in accordance with the smear level. It is possible to obtain a higher-quality image in which natural conspicuous false signals are reduced or eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a digital video camera according to an embodiment of an imaging apparatus according to the present invention.

FIG. 2 is a diagram illustrating input / output characteristics without correction and input / output characteristics of a conventional smear correction in comparison with smear correction according to an embodiment of the present invention.

FIG. 3 is a diagram showing input / output characteristics of a smear correction unit for explaining a mode of smear correction in the embodiment shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens system 2 Lens drive mechanism 3 Exposure control mechanism 4 Filter system 5 CCD image sensor 6 CCD driver 7 Pre-process circuit 8 Digital process circuit 8-1 Smear level detector 8-2 Output degradation pixel determiner 8-3 Compensation condition determination Unit 8-4 Data compensation unit 8-5 Smear correction unit 9 Recording unit 10 Video tape 11 LCD image display system 12 System controller 13 Operation switch system 14 Operation display system 15 Lens driver 16 Exposure control driver 17 EEPROM

Claims (16)

[Claims] 1. A smear detecting means for detecting a smear component of an image sensor based on an image sensor output corresponding to a vertical blanking period, and a level of the smear component detected by the smear detecting means exceeds a predetermined value. An output degradation pixel judging means for judging an effective signal pixel corresponding to the output degradation pixel as an output degradation pixel. 2. A smear detecting means for detecting a smear component of the image sensor based on an image sensor output corresponding to a vertical blanking period, and a level of the smear component detected by the smear detecting means exceeds a predetermined value. When the output level of the corresponding effective signal pixel reaches a predetermined saturation level, the output deterioration pixel determining means for determining the output deterioration pixel as an output deterioration pixel. . 3. The imaging apparatus according to claim 1, further comprising a compensation condition determining unit that determines whether a predetermined compensation condition is satisfied for the output deteriorated pixel. 4. A smear level detecting means for detecting a smear level generated in an effective pixel of the image sensor based on a signal output from a light-shielded pixel column of the image sensor during a vertical blanking period, and the smear level detection. When the smear level detected by the means exceeds a predetermined value, a deteriorated pixel determining means for determining an effective pixel corresponding to the smear level as an output deteriorated pixel, and a signal from a pixel determined as an output deteriorated pixel by the deteriorated pixel determining means. When a predetermined saturation level is reached, a compensation condition determining means for determining whether or not a predetermined compensation condition is satisfied for the deteriorated pixel; and a deteriorated pixel determined to satisfy the compensation condition by the compensation condition determining means. An image pickup apparatus comprising: a deteriorated pixel correction unit that replaces a signal from a degraded pixel with a non-degraded pixel signal near the deteriorated pixel. 5. The deteriorated pixel correcting means corrects an output level of a signal from a deteriorated pixel determined not to satisfy the compensation condition according to a smear level detected by the smear level detecting means. The imaging device according to claim 4, wherein the imaging device is configured to perform the operation. 6. The smear level of the image sensor detected by the smear level detecting means is obtained by dividing a sum of signal levels from a light-shielded pixel row of the same horizontal address by a total number of pixels in the same light-shielded pixel row. The imaging device according to claim 4, wherein: 7. The predetermined compensation condition is a condition that at least one non-deteriorated pixel column is included in four neighboring pixel columns centered on the degraded pixel column. The imaging device according to 4 or 5. 8. The correction of the output level according to the smear level performed by the deteriorated pixel correction means is a correction that subtracts the detected smear level from the deteriorated pixel level and multiplies the coefficient based on the saturation level and the detected smear level. The imaging device according to claim 5, wherein: 9. A step of detecting a smear component of the image sensor based on an output of the image sensor corresponding to a vertical blanking period, and the level of the smear component detected in the smear component detection step exceeds a predetermined value. And a step of determining an output-deteriorated pixel corresponding to the valid signal pixel as an output-deteriorated pixel. 10. A step of detecting a smear component of the image sensor based on an image sensor output corresponding to a vertical blanking period, and the level of the smear component detected in the smear component detection step exceeds a predetermined value. When the output level of the corresponding effective signal pixel has reached a predetermined saturation level, the output deterioration pixel determining step of determining this as an output deterioration pixel. The method of correcting a deteriorated pixel signal. 11. The correction of a deteriorated pixel signal of the imaging apparatus according to claim 9, further comprising a compensation condition determining step of determining whether a predetermined compensation condition is satisfied for the output deteriorated pixel. Method. 12. A step of detecting a smear level generated in an effective pixel of the image sensor based on a signal output from a light-shielded pixel column of the image sensor during a vertical blanking period, and detecting the smear level in the smear level detecting step. When the smear level exceeds the predetermined value, the valid pixel corresponding to the smear level is determined as an output deteriorated pixel, and the signal from the pixel determined as the output deteriorated pixel in the deteriorated pixel determination step is set to a predetermined saturation level. Determining whether the degraded pixel satisfies a predetermined compensation condition; and determining a signal from the degraded pixel that is determined to satisfy the compensation condition in the compensation condition determination step, by comparing the degraded pixel with the degraded pixel neighborhood. A method of correcting a deteriorated pixel signal of an imaging device, the method further comprising the steps of: 13. The deteriorated pixel correction step corrects an output level of a signal from a deteriorated pixel determined not to satisfy the compensation condition according to the smear level detected in the smear level detection step. 13. The method for correcting a deteriorated pixel signal of an imaging device according to claim 12, further comprising the step of: 14. The smear level of the image sensor detected in the smear level detection step is obtained by dividing the sum of signal levels from the light-shielded pixel row at the same horizontal address by the total number of pixels in the same light-shielded pixel row. Claims characterized by the following
12. The method for correcting a deteriorated pixel signal of the imaging device according to 12 or 13. 15. The predetermined compensation condition is a condition that at least one non-degraded pixel column is included in four neighboring pixel columns having the degraded pixel column at the center. 12. The method for correcting a deteriorated pixel signal of the imaging device according to 12 or 13. 16. The correction of the output level according to the smear level in the deteriorated pixel correction step is performed by subtracting the detected smear level from the deteriorated pixel level and multiplying the coefficient based on the saturation level and the detected smear level. 14. The method for correcting a deteriorated pixel signal of an imaging device according to claim 13, wherein: