JP2011049873A - Imaging apparatus, image processing method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reconcile reduction of smear and reduction of black floating. <P>SOLUTION: A gamma setting part 9B reads and sets a normal standard gamma correction curve from a gamma storage part 9A when brightness (such as the whole average value, an average value of brightness at a predetermined part) of an object is not equal to or more than a predetermined value, reads and sets a gamma correction curve for black floating reduction from the gamma storage part 9A when the brightness is equal to or more than the predetermined value in moving image photography. A gamma correction processing part 9C performs gamma correction processing using the standard gamma correction curve when the brightness of the object is not equal to or more than the predetermined value, and meanwhile, performs the gamma correction and black floating reduction processing using the gamma correction curve for black floating reduction to which correction by shifting the black side of the standard gamma correction curve is performed when the brightness is equal to or more than the predetermined value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, an image processing method, and a program.

  Conventionally, in an imaging device (such as a digital camera or a video camera) having a CCD as an imaging device, if a strong point light source is reflected in the structure of a photodiode of a light receiving unit or a charge transfer unit, the captured image is vertically It is known that a phenomenon called streak smear extending to the surface appears.

  As a countermeasure against the occurrence of smear, for example, a smear value detected by a smear detection unit (optical black region) provided above and below (left and right) of the imaging area is subtracted (smear subtraction) at a predetermined ratio, and is generated in the image. There is known a digital camera provided with smear subtracting means for reducing streak smear (see, for example, Patent Document 1).

  However, in this prior art, it is good as long as there are few smears, but when there are many smears, if the smear subtraction is completely subtracted (100%) to cope with only smear subtraction, the subtracted part becomes a black line. Therefore, it can only be half-subtracted (no black line appears). For this reason, there is a problem in that the image becomes a video with a low contrast in which the image is blackened.

  On the other hand, there is known a digital camera provided with black enhancement means for reducing black float generated in the entire image by changing the correction curve on the black side of the gamma correction table (see, for example, Patent Document 2).

JP 2006-324976 A JP 2006-94031 A

  By the way, in the case of still image shooting, after the exposure with the photodiode is completed, the transfer period (reading) is performed by closing the mechanical shutter (hereinafter also referred to as the mechanical shutter) during the transfer of the electric charge accumulated by the exposure. The influence of a strong light source in the period) can be suppressed. However, in the case of moving image shooting, since the operation sound is generated when the mechanical shutter is opened and closed every time one frame is imaged, it is normal not to use the mechanical shutter. For this reason, in the case of moving image shooting, the influence of a strong light source in the transfer period cannot be suppressed, and more smear occurs.

  In addition, when the ratio of the transfer period to the exposure period is increased, not only the streak smear due to the point light source but also a wider range of brightness affects the smear occurrence, and the smear is generated over the entire image. Often become blackish.

  Whether a streak smear or black out of the entire image varies depending on the ratio of the transfer period to the exposure period, the brightness of the subject, the spread of the light source, the shooting conditions, and the like.

  In addition, in the case of still image shooting, image correction suitable for each image can be performed for each image, so it is relatively easy to optimize both smear and black float. However, in the case of moving image shooting, since it is necessary to maintain continuity between images, the correction content cannot be changed greatly for each image, and the above-described smear reduction technique or gamma correction technique according to the conventional technique described above. However, there is a problem that it is difficult to achieve both the reduction of the smear and the reduction of the black float.

  Therefore, an object of the present invention is to provide an imaging apparatus, an image processing method, and a program that can achieve both reduction of smear and reduction of black float in moving image shooting.

  In order to achieve the above object, an invention according to claim 1 is directed to an image sensor for photographing a subject, storage means for storing gradation correction information serving as a reference applied at the time of shooting, and low gradation correction information serving as a reference. Black enhancement means for reducing black float generated in the entire captured image captured by the image sensor by changing a value on the gradation side, and the black enhancement means has a brightness of the subject equal to or greater than a predetermined value The amount of streak smear generated in the captured image is greater than or equal to a predetermined value, the exposure period is less than or equal to a predetermined value, the shutter speed is greater than or equal to a predetermined value, or the ratio of the non-exposure period in the field is greater than or equal to a predetermined value. In this case, the image pickup apparatus is characterized in that black float reduction processing is performed on a picked-up image picked up by the image pickup element.

  Further, as a preferred aspect, for example, as in claim 2, in the image pickup apparatus according to claim 1, the image pickup device performs moving image shooting or shooting in an environment where a mechanical shutter cannot be used. To do.

  Further, as a preferred aspect, for example, as in claim 3, in the imaging device according to claim 1 or 2, the imaging element has at least a smear detection region, and is based on a pixel value of the smear detection region. The smear detecting means for detecting a streak smear generated in the picked-up image picked up by the image pickup device, and the pixel value corresponding to the smear detected by the smear detecting means by subtracting at a predetermined ratio, the image pick-up It further comprises smear reducing means for reducing smear generated in the picked-up image picked up by the element.

  Further, as a preferred aspect, for example, as in claim 4, in the image pickup apparatus according to any one of claims 1 to 3, the black enhancement means is configured such that the brightness of the subject, a streak generated in the picked-up image is generated. The larger the value of any of the smear amount, the reciprocal of the exposure period, the shutter speed, or the ratio of the non-exposure period in the field, the greater the strength of the black float reduction process.

  Further, as a preferable aspect, for example, as in claim 5, in the imaging apparatus according to any one of claims 1 to 4, a designation unit that designates a contrast correction strength of a captured image by a user operation, and the designation unit Contrast changing means for changing gradation correction information, which is stored in the storage means and serves as a reference applied at the time of shooting, according to the designated contrast correction intensity, further comprising: By changing the value on the low gradation side of the gradation correction information changed by the means, the black float generated in the entire captured image captured by the imaging element is reduced.

  Further, as a preferred aspect, for example, as in claim 6, in the imaging device according to any one of claims 1 to 5, presence or absence of a black float reduction process by the black enhancement means or a black float reduction process by a user operation It is further characterized by further comprising a change means for instructing a change in the intensity of.

  In order to achieve the above object, the invention described in claim 7 includes a step of photographing a subject with an image sensor, a brightness of the subject being a predetermined value or more, and a streak smear amount occurring in the captured image being a predetermined value or more. If the exposure period is equal to or less than a predetermined value, the shutter speed is equal to or greater than a predetermined value, or the ratio of the non-exposure period in the field is equal to or greater than a predetermined value, And a step of reducing black float generated in the entire captured image captured by the imaging device by changing a value on a low gradation side.

  In order to achieve the above object, the invention according to claim 8 is directed to a computer of an image pickup apparatus that picks up a subject with an image pickup device, an image pickup function for picking up a subject with the image pickup device, and the brightness of the subject is a predetermined value or more. When the amount of streak smear generated in the captured image is greater than or equal to a predetermined value, the exposure period is less than or equal to a predetermined value, the shutter speed is greater than or equal to a predetermined value, or the ratio of the non-exposure period in the field is greater than or equal to a predetermined value In addition, by changing the value on the low gradation side of the gradation correction information that is a reference applied at the time of shooting, a black floating reduction function for reducing black floating that occurs in the entire captured image captured by the image sensor is executed. It is a program characterized by this.

  According to the present invention, the brightness of the subject is greater than or equal to a predetermined value, the amount of streak smear generated in the captured image is greater than or equal to the predetermined value, the exposure period is less than or equal to the predetermined value, the shutter speed is greater than or equal to the predetermined value, or non-in-field When the ratio of the exposure period is greater than or equal to a predetermined value, the black float reduction process is performed on the captured image captured by the image sensor. There is an advantage that both reduction can be achieved.

It is a block diagram which shows the structure of the digital camera 1 by this 1st Embodiment. It is a conceptual diagram which shows the relationship between read-out timing and shutter speed. It is a conceptual diagram which shows the difference in the black float generation | occurrence | production state by the brightness at the time of still image photography. It is a conceptual diagram which shows the difference in the black float generation | occurrence | production situation by the brightness at the time of video recording. It is a conceptual diagram for demonstrating an example of a standard gamma correction curve and a gamma correction curve for black float reduction. 4 is a flowchart for explaining an operation of the digital camera 1 according to the first embodiment. It is a mimetic diagram for explaining smear amount detection at the time of performing black float processing according to the amount of smear by the 2nd embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A. First embodiment A-1. Configuration of First Embodiment FIG. 1 is a block diagram showing a configuration of a digital camera 1 according to the first embodiment.
The digital camera 1 includes a photographic lens 2, a lens driving block 3, an aperture / shutter 4, a CCD 5, and a TG (timing
generator) 6, unit circuit 7, smear removal processing unit 8, gamma storage unit 9A, gamma setting unit 9B, gamma correction processing unit 9C, CPU 11, DRAM 12, memory 13, flash memory 14, image display unit 15, key input unit 16 , A strobe drive unit 17, a strobe light emitting unit 18, and a card I / F 19. A memory card 20 detachably attached to a card slot of the digital camera 1 (not shown) is connected to the card I / F 19. ing.

  The photographing lens 2 includes a focus lens and a zoom lens (not shown), and a lens driving block 3 is connected thereto. The lens driving block 3 includes a motor for driving a focus lens and a zoom lens (not shown) in the optical axis direction, a focus motor driver for driving the focus motor and the zoom motor in the optical axis direction according to a control signal from the CPU 11, and a zoom. It consists of a motor driver.

  The diaphragm 4 includes a drive circuit (not shown), and the drive circuit operates the diaphragm in accordance with a control signal sent from the CPU 11. The diaphragm 4 controls the amount of light that enters from the taking lens 2. In addition, the digital camera according to the first embodiment includes an electronic shutter mechanism (not shown), and controls the time during which light is applied to the CCD 5 by the electronic shutter mechanism. The exposure can be determined by the aperture and the shutter speed.

  The CCD 5 (imaging device) converts the light of the subject projected via the photographing lens 2, the aperture shutter 4, and the electronic shutter mechanism into an electrical signal and outputs it as an imaging signal to the unit circuit 7. The CCD 5 is driven in accordance with a predetermined frequency timing signal generated by the TG 6. Since the CCD 5 is an interline CCD, the pixel signals of the pixels of the CCD 5 are read line by line from the lower line of the CCD 5 to the upper line.

The unit circuit 7 is a CDS (Correlated) that holds the imaging signal output from the CCD 5 by correlated double sampling.
Double Sampling) circuit, AGC (Automatic) for automatic gain adjustment of the imaged signal after sampling
Gain control) circuit, and an A / D converter that converts the analog image pickup signal after the automatic gain adjustment into a digital signal. The image pickup signal of the CCD 5 passes through the unit circuit 7 and becomes a smear removal processing unit as a digital signal. 8 is sent. Note that the TG 6 is connected to the unit circuit 7.

  The smear removal processing unit 8 evaluates whether or not the smear is removed from the image data (digital signal) sent from the unit circuit 7 and removes the smear according to the evaluated strength. Output to the gamma correction processing section 9C. A TG 6 is connected to the smear removal processing unit 8.

  The gamma storage unit 9A is used when at least smear does not occur (or when the smear amount is equal to or less than a predetermined threshold) and the standard gamma correction curve used in normal times and when black float spreads throughout the image due to smear. A gamma correction curve for reducing black float is stored. This standard gamma correction curve is stored separately for the standard gamma correction curve for still images and the standard gamma correction curve for moving images. When shooting still images, the standard gamma correction curve for still images is corrected. Thus, a gamma correction curve for reducing black float is set, and at the time of moving image shooting, a gamma correction curve for reducing black float is set by correcting the standard gamma correction curve for moving image. In the following description, the gamma correction curve used during moving image shooting may be referred to as a movie gamma correction curve, and a specific example of this movie gamma correction curve will be described later.

  The gamma setting unit 9B reads the standard gamma correction curve (gradation correction information) from the gamma storage unit 9, and responds to the LV value (index indicating brightness) of the image data (digital signal) sent from the unit circuit 7. Then, the read standard gamma correction curve (gradation correction information) is read out, corrected as described later, and set as a black float reduction gamma correction curve.

  The gamma correction processing unit 9C was photographed by performing gamma correction processing on the smear-removed image data from the smear removal processing unit 8 using the set gamma correction curve for reducing black float. A standard gamma correction process is performed on the image, and at the same time, the black float is corrected.

  The CPU 11 performs image processing (pixel interpolation processing, γ correction, luminance color difference signal generation, white balance processing, exposure correction processing, etc.) of the image data sent from the unit circuit 7, and compression / decompression (for example, JPEG) of the image data. Format, M-JPEG format or MPEG format compression / decompression), and a function for outputting information necessary for the smear removal processing unit 8 (horizontal OB address information, vertical OB address information, etc.) This is a one-chip microcomputer that controls each part of the digital camera 1.

  The DRAM 12 is used as a buffer memory for temporarily storing image data sent to the CPU 11 after being imaged by the CCD 5 and also as a working memory for the CPU 11. The memory 13 stores a program necessary for controlling each part of the digital camera 1 by the CPU 11 and data necessary for controlling each part, and the CPU 11 performs processing according to this program. The flash memory 14 and the memory card 20 are recording media for storing image data captured by the CCD 5.

  The image display unit 15 includes a color LCD and its drive circuit, and displays the subject imaged by the CCD 5 as a through image when in the shooting standby state, and when reproducing the recorded image, the storage flash memory 14 and the memory card. The recorded image read out from 20 and expanded is displayed. The key input unit 16 includes a plurality of operation keys such as a shutter button, a mode key, a SET key, and a cross key, and outputs an operation signal corresponding to the user's key operation to the CPU 11.

  The strobe driving unit 17 drives the strobe light emitting unit 18 to flash in accordance with a control signal from the CPU 11, and the strobe light emitting unit 18 flashes the strobe. The CPU 11 determines whether or not the shooting scene is dark by a photometric circuit (not shown), determines that the shooting scene is dark, and determines that shooting is to be performed (when the shutter button is pressed), the CPU 11 Send a control signal.

Next, the relationship between brightness and occurrence of smear will be described.
In a digital camera, when the aperture and sensitivity are constant, the shutter speed increases as the LV value indicating brightness increases. For example, at F7.0, ISO64,
14LV⇒Shutter speed is 1 / 200s,
15LV⇒Shutter speed is 1 / 400s.

In moving image shooting, the mechanical shutter cannot be used, and the smear increases as the shutter speed increases due to the characteristics of the CCD. That is, the actual efficiency of smear varies depending on the ratio between the shutter speed and the readout timing. The actual efficiency of smear is
Actual smear efficiency = smear specification efficiency x shutter speed / readout timing.

For example, as shown in FIG. 2, when the readout timing is 1 field 1/30 s and the shutter speed is 1/300 s, the actual efficiency of smear becomes 1/10 times the specification efficiency. That means
14LV⇒1 / 200 ÷ 1/30 = 0.15,
15LV⇒1 / 400 ÷ 1/30 = 0.075.
Therefore, smear is more likely to occur in a bright environment.

  As described above, it was found that smear due to a strong point light source is likely to occur in a bright environment. In the smear removing process for removing such smears, as described in the prior art, even when there are many smears, only half-subtraction (a level where no black line is generated) can be performed, so the captured image is blackened. The image will have a reduced contrast.

  Next, the occurrence of black float will be described. When shooting a still image or movie with a digital camera, even if there is no strong point light source, that is, even in an environment where streak smear does not occur, a relatively bright background is reflected, etc. The dark part may become a whitish image, that is, an image that is black. This black floating is more likely to occur as the exposure period for taking incident light into the CCD is shorter.

  FIGS. 3A and 3B are conceptual diagrams showing the difference in the occurrence of black float due to brightness during still image shooting. In the case of a still image, the case where the subject shown in FIG. 3A is bright (when the amount of incident CCD light is large) is compared with the case where the subject shown in FIG. 3B is dark (when the amount of incident CCD light is small). Since the CCD is adjusted so that the amount of incident light is optimal, the exposure period when the subject is bright is shorter than the exposure period when the subject is dark. In either case, the readout period from the CCD is constant, and the mechanical shutter can be closed during the readout period, so the exposure period and the incident period to the CCD are the same. In still image shooting, as shown in FIGS. 3A and 3B, the shorter the exposure period (the higher the shutter speed), the brighter the subject, so smearing or black floating tends to occur. It can be said that it is below.

  4 (a) and 4 (b) are conceptual diagrams showing the difference between the occurrence of smear and black float due to brightness during moving image shooting. For moving images, the mechanical shutter is not used. Therefore, when the subject shown in FIG. 4A is bright (when the amount of incident CCD light is large) and when the subject shown in FIG. 4B is dark (when the amount of incident CCD light is small), Since the amount of incident light on the CCD is optimized by adjusting the diaphragm and the like, the exposure period when the subject is bright is shorter than the exposure period when the subject is dark. In moving image shooting, in any case, the readout period from the CCD is constant, and the mechanical shutter is not used. Therefore, the incident period to the CCD is the sum of the exposure period and the readout period (constant). As shown in FIGS. 4A and 4B, the shorter the exposure period (the higher the shutter speed), the brighter the subject, so it can be said that the environment is prone to smearing or black floating.

  Therefore, in the first embodiment, when the brightness is equal to or higher than a predetermined threshold (for example, 15 LV), as shown in FIG. 5, only a part (black side) of the standard gamma correction curve (solid line) for moving images is used. Is corrected by shifting to a black floating reduction gamma correction curve indicated by a broken line, thereby correcting black floating caused by reflection of a strong light source. In the first embodiment, the threshold value is divided by one threshold value, but a plurality of threshold values may be set, and the black float reduction gamma correction curve may be changed in multiple stages. In FIG. 5, as the broken line portion is shifted in the direction of the arrow, the strength of the black floating reduction process is increased.

A-2. Operation of First Embodiment Next, the operation of the first embodiment described above will be described.
FIG. 6 is a flowchart for explaining the operation of the digital camera 1 according to the first embodiment. First, it is determined whether or not to shoot a moving image (step S10). If it is not moving image shooting (still image shooting), the mechanical shutter is enabled (step S12), and a normal image is set from the gamma storage unit 9A by the normal gamma setting unit 9B. The gamma correction curve is read and set (step S14), the brightness (the average value of the whole, the average value of the brightness at a predetermined location, etc.) is measured (step S16), and the exposure conditions such as the aperture and shutter speed are measured. Is set (step S18). Next, a still image is photographed (step S20), image processing including haze removal processing is performed (step S22), and the still image after image processing is recorded (step S24).

  On the other hand, in the case of moving image shooting, the mechanical shutter is invalidated (step S26), the aperture is set to a fixed value (step S28), and the brightness (the average value of the whole, the average value of the brightness at a predetermined location, etc.) is measured. (Step S30), a shutter speed corresponding to the brightness is set (Step S32), and a moving image frame is shot (Step S34). Next, the smear removal processing unit 8 determines whether smear has occurred (step S36). If smear has occurred, a smear removal process is performed (step S38). On the other hand, if smear has not occurred, the process proceeds to step S40 without performing smear removal processing.

  Next, it is determined whether or not the brightness is equal to or greater than a predetermined value (for example, LV15) (step S40). If the brightness is not equal to or greater than the predetermined value, the gamma setting unit 9B reads the normal value from the gamma storage unit 9A. The standard gamma correction curve (solid line in FIG. 5) is read and set (step S44), and the gamma correction processing unit 9C performs gamma correction processing based on the set normal standard gamma correction curve (step S46) and compresses it. Then, it is additionally recorded in the moving image file (step S48), and it is determined whether or not the moving image shooting is completed (step S50). If the moving image shooting has not ended, the process returns to step S30 and the above-described processing is repeated. On the other hand, when the moving image shooting is finished, the processing is finished.

  On the other hand, when the brightness is equal to or higher than a predetermined value (for example, LV15), the gamma setting unit 8 reads a normal standard gamma correction curve from the gamma storage unit 9A, performs correction by shifting the black side, and performs black correction. It is set as a floating reduction gamma correction curve (broken line in FIG. 5) (step S22), and the gamma correction processing unit 9C performs black floating reduction processing based on the set black floating reduction gamma correction curve (step S46). It is compressed and additionally recorded in the moving image file (step S48), and it is determined whether or not moving image shooting is completed (step S50). If the moving image shooting has not ended, the process returns to step S30 and the above-described processing is repeated. On the other hand, when the moving image shooting is finished, the processing is finished.

  In other words, when gamma correction processing is performed using the standard gamma correction curve, only normal gamma correction is performed, and when gamma correction processing is performed using the black float reduction gamma correction curve, the normal gamma correction is performed. Black float reduction processing is performed simultaneously with gamma correction.

  According to the first embodiment described above, even when shooting in an environment where the brightness exceeds a predetermined value and smear or black floating is likely to occur, black floating is corrected using the black floating reduction gamma correction curve. By doing so, it is possible to reduce a decrease in contrast due to black floating.

B. Modified Example Next, a modified example of the first embodiment will be described.
The configuration of the digital camera 1 is the same as that shown in FIG. In the first embodiment described above, the gamma correction curve for reducing the black float in which the standard gamma correction curve is corrected according to the brightness is used. However, in this modification, when the smear exceeds a certain amount, the gamma correction curve is used. And is set as a gamma correction curve for reducing black float.

  As shown in FIG. 7, the CCD 5 includes an effective pixel area 5-1 for obtaining subject information and a vertical optical black (vertical OB) area 5-2 for determining a black reference in the vertical direction. In practice, the horizontal for determining the black reference in the horizontal direction is located above the effective pixel region 5-1, and further to the left and right of another vertical optical black (vertical OB) region and effective pixel region 5-1. Although an optical black (horizontal OB) region is provided, only the vertical optical black (vertical OB) region 5-2 will be described here for the sake of simplicity.

  The optical black area 5-2 is formed by attaching a light shielding film to the CCD 5 (up, down, left and right). That is, an image signal corresponding to a black image is obtained in the optical black area 5-2. In addition, 5-3 is a high-intensity light source, and 5-4 is the smear which generate | occur | produced.

  As shown in FIG. 7, when a high-intensity light source 5-3 such as the sun or a headlight of an automobile is imaged by the CCD 5, a white vertical line called smear 5-4 is generated. The pixel data of one line having the vertical optical black region 5-2 is basically pixel data when a black subject is imaged. However, when smear 5-4 occurs, the pixel data of the portion of the pixel that has occurred is generated. Only the data is a signal to which the smear signal 5-5 is added.

  Since the CCD 5 is an interline CCD, the pixel signals of the pixels of the CCD 5 are read line by line from the lower line of the CCD 5 to the upper line. That is, the pixel signal in the vertical optical black region 5-2 is read first, sequentially read from the lower line to the upper line, and finally the uppermost pixel signal is read.

  Therefore, in the modification of the first embodiment, the smear amount is detected from the pixel data value of the smear detection unit 5-5 in the vertical optical black (vertical OB) region 5-2 shown in FIG. 7, and the smear amount is a predetermined value. If not, the normal standard gamma correction curve (solid line in FIG. 5) is read and set from the gamma storage unit 9A by the gamma setting unit 9B and set to the set normal standard gamma correction curve by the gamma correction processing unit 9C. Based on this, a gamma correction process is performed.

  On the other hand, when the amount of smear is equal to or larger than the predetermined value, the gamma setting unit 9B reads a normal standard gamma correction curve from the gamma storage unit 9A, performs correction by shifting the black side, and performs gamma correction for reducing black floating. Set as a curve (broken line in FIG. 5), the gamma correction processing unit 9C performs black float reduction processing based on the set black float reduction gamma correction curve.

  According to the above-described modification of the first embodiment, when the smear amount exceeds a predetermined value, the black float is corrected by changing to the black float reduction gamma correction curve, thereby reducing the contrast due to the black float. Can be reduced.

  In the first embodiment or the modification described above, the black float reduction process is performed according to the brightness or the smear amount. However, the present invention is not limited to this, and the exposure period is a predetermined value or less and the shutter speed is a predetermined value. The black float reduction processing may be performed when one of the above conditions or the condition where the ratio of the non-exposure period in the field is equal to or greater than a predetermined value is satisfied.

  In addition, the greater the value of brightness, the reciprocal of the exposure period, the shutter speed, the ratio of the non-exposure period in the field, or the amount of streak smear that occurs in the captured image, the greater the intensity of black float reduction. The characteristic of the gamma correction curve for reducing the black float may be changed so as to increase.

  Some digital cameras can specify the contrast correction intensity (or exposure) of the captured image by the user's operation from the key input unit 16. In such a case, the contrast correction specified by the user operation is performed. According to the intensity, the standard gamma correction curve stored in the gamma storage unit 9A is changed, and the gamma correction processing unit 9C changes the value on the low gradation side of the changed standard gamma correction curve. You may make it reduce the black float produced in the whole.

  Further, the presence / absence of the black float reduction process or the intensity thereof may be changed through a menu setting or the like by a user operation from the key input unit 16.

1 Digital Camera 2 Shooting Lens 3 Lens Drive Block 4 Shutter / Shutter 5 CCD
6 TG
7 Unit Circuit 8 Smear Removal Processing Unit 9A Gamma Storage Unit 9B Gamma Setting Unit 9C Gamma Correction Processing Unit 11 CPU
12 DRAM
13 Memory 14 Flash Memory 15 Image Display Unit 16 Key Input Unit 17 Strobe Drive Unit 18 Strobe Light Emitting Unit 19 Card I / F
20 Memory card

Claims (8)

An image sensor for photographing a subject;
Storage means for storing gradation correction information serving as a reference applied at the time of shooting;
Black enhancement means for reducing black float generated in the entire captured image captured by the image sensor by changing a value on the low gradation side of the reference gradation correction information,
The black enhancement means is
The brightness of the subject is greater than or equal to a predetermined value, the amount of streak smear generated in the captured image is greater than or equal to a predetermined value, the exposure period is less than or equal to a predetermined value, the shutter speed is greater than or equal to a predetermined value, or the ratio of the non-exposure period in the field is predetermined If any of the values is greater than or equal to the condition, a black float reduction process is performed on the captured image captured by the image sensor.
An imaging apparatus characterized by that. The image sensor is
Shooting movies or shooting in environments where mechanical shutters are not available,
The imaging apparatus according to claim 1. The image sensor has at least a smear detection region,
Smear detection means for detecting streak smears generated in the captured image captured by the image sensor based on the pixel value of the smear detection region;
And further comprising a smear reducing means for reducing smear generated in a captured image picked up by the image pickup device by subtracting a pixel value corresponding to the smear detected by the smear detecting means at a predetermined ratio. The imaging apparatus according to claim 1 or 2. The black enhancement means is
As the value of the subject brightness, the amount of streak smear generated in the captured image, the reciprocal of the exposure period, the shutter speed, or the ratio of the non-exposure period in the field increases, the black float reduction Increase the strength of processing,
The image pickup apparatus according to claim 1, wherein the image pickup apparatus is an image pickup apparatus. A designation means for designating a contrast correction strength of a captured image by a user operation;
Contrast changing means for changing gradation correction information, which is stored in the storage means and serves as a reference to be applied at the time of shooting, according to the contrast correction strength specified by the specifying means,
The black enhancement means reduces the black float generated in the entire captured image captured by the image sensor by changing the value on the low gradation side of the gradation correction information changed by the contrast changing means.
The imaging apparatus according to claim 1, wherein:   6. The imaging apparatus according to claim 1, further comprising changing means for instructing, by a user operation, presence or absence of a black float reduction process by the black enhancement means or a change in intensity of the black float reduction process. . Photographing a subject with an image sensor;
The brightness of the subject is greater than or equal to a predetermined value, the amount of streak smear generated in the captured image is greater than or equal to a predetermined value, the exposure period is less than or equal to a predetermined value, the shutter speed is greater than or equal to a predetermined value, or the ratio of the non-exposure period in the field is predetermined If any of the above values satisfies the condition, changing the value on the low gradation side of the gradation correction information that is the reference applied at the time of shooting changes the black floating that occurs in the entire captured image captured by the image sensor And an image processing method comprising: In the computer of the imaging device that images the subject with the imaging element,
An imaging function for photographing a subject by the imaging element;
The brightness of the subject is greater than or equal to a predetermined value, the amount of streak smear generated in the captured image is greater than or equal to a predetermined value, the exposure period is less than or equal to a predetermined value, the shutter speed is greater than or equal to a predetermined value, or the ratio of the non-exposure period in the field is predetermined If any of the above values satisfies the condition, changing the value on the low gradation side of the gradation correction information that is the reference applied at the time of shooting changes the black floating that occurs in the entire captured image captured by the image sensor A program characterized by executing a black float reduction function for reducing noise.

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