JP2017163339A - Video processing apparatus, video processing method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable displaying of a video image that is highly visible for a user, when displaying a video image being captured on a display device.SOLUTION: When displaying a video image consisting of a video signal being captured on a display (116), a gamma correction part (113) performs first correction processing based on a first gamma characteristic corresponding to a gamma characteristic for high luminance priority mode on a video signal on which correction processing based on the gamma characteristic for high luminance priority mode has been performed. When performing predetermined imaging assist display in the case where a video image consisting of a video signal being captured is to be displayed on a display device, a camera microcomputer (111) causes the gamma correction part (113) to perform gamma correction based on a second gamma characteristic that improves display luminance of the display (116) rather than the first gamma characteristic.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a video processing apparatus, a video processing method, and a program for processing a video signal.

2. Description of the Related Art Conventionally, in a video processing system that captures a subject or the like with an imaging device and displays the captured video on a display device, luminance gradation correction processing by gamma correction is performed on both the imaging device and the display device. The imaging device performs gradation correction processing (gamma correction processing) that converts the luminance of the video signal being captured into an output code value based on the gamma characteristics of the imaging device. On the other hand, the display device performs gradation correction processing (gamma correction processing) that converts the input code value of the video signal into an output luminance value based on the gamma characteristic of the display device. This makes it possible to cut out a limited range of brightness from the brightness of a real-world subject with a very wide dynamic range and display it within the limited narrow dynamic range of the monitor display of the display device. Is possible.
Further, as a technique of gradation correction processing for securing a practical input dynamic range in an imaging apparatus, Patent Document 1 discloses a technique for expanding an input dynamic range by performing gamma correction processing including knee correction processing. Has been.

JP 2002-223373 A

  Here, the gamma correction process including the knee correction process is a gradation correction process that compresses the contrast in a medium to high luminance region while ensuring a practical input dynamic range. In this way, when the contrast of the medium to high luminance region is compressed, the gradation characteristics of the video processing system as a whole consisting of the imaging device and the display device are such that the contrast of the high luminance portion is compressed with respect to the low luminance portion. It becomes an unnatural characteristic. In this case, for example, if the system-wide gradation characteristic that combines the gamma characteristic of the imaging device and the gamma characteristic of the display device is linear, the display device has a wide range from the low luminance part to the high luminance part. It is considered that linear gradation display is possible.

  However, in this case, although the image displayed on the display device is linear in gradation, it appears to the human eye as a dark image having, for example, low to medium luminance (hereinafter referred to as low to medium luminance). As a result, the image is less visible when viewed from the user. As described above, in the case of a display image in which low and medium luminances appear dark, it is difficult for the user to perform correct exposure setting at the time of shooting, for example, while viewing the display image.

  In view of the above, an object of the present invention is to enable display of a video with high visibility for a user when displaying a video being shot on a display device.

  In the present invention, when a predetermined shooting assist display is performed when displaying a video based on a video signal being shot on a display device, the video signal after correction processing using a predetermined gamma characteristic is performed. A correction process is performed using a second gamma characteristic that increases the display brightness of the display device over the first gamma characteristic corresponding to the predetermined gamma characteristic.

  ADVANTAGE OF THE INVENTION According to this invention, when displaying the image | video currently image | photographed on a display apparatus, the display of an image | video with high visibility for a user is attained.

It is a figure which shows the schematic structural example of the video camera of this embodiment. It is a general-view perspective view of a video camera. It is explanatory drawing of the gamma characteristic in this embodiment. It is a figure used for description of photographing assistance display and gamma characteristic change. It is a flowchart of control of a video camera. It is a flowchart which shows the display brightness setting process at the time of camera mode. It is a figure which shows the example of a screen display at the time of changing a gamma characteristic.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
<Internal configuration of video camera>
FIG. 1 is a diagram illustrating a schematic configuration of a video camera 201 which is an application example of the video processing apparatus according to the present embodiment. The video camera 201 of this embodiment is a video processing system in which an imaging device and a display device are integrated.

  The lens 101 forms a subject image on the imaging surface of the image sensor 105. The diaphragm 102 adjusts the amount of light incident from the lens 101. The image sensor 105 converts a subject image formed on the imaging surface via the lens 101 and the diaphragm 102 into a video signal. An analog-to-digital (A / D) converter (not shown) or the like is provided after the image sensor 105, and a digital video signal obtained by encoding an analog video signal by A / D conversion is sent to the signal processing unit 112. Note that the lens 101 may have a lens shift type camera shake correction function that shifts a camera shake correction optical system in a direction orthogonal to the optical axis. The camera shake correction may be a sensor shift method in which the position of the image sensor 105 is changed with respect to the optical axis of the lens 101, or a readout control method in which camera shake correction is performed by controlling readout from the image sensor 105. May be.

  The signal processing unit 112 includes a white balance correction unit 107, an edge enhancement unit 108, gamma (γ) correction units 109 and 113, and a luminance / color information detection unit 110. In the following description, white balance is expressed as “WB”. The WB correction unit 107 performs white balance correction processing on the video signal from the image sensor 105. The edge enhancement unit 108 performs edge enhancement processing on the video signal after the WB correction processing.

  The gamma correction unit 109 is a gamma correction unit for photographed video that performs gamma correction processing based on the gamma characteristics of the imaging device for the luminance of the video signal supplied from the edge enhancement unit 108. The gamma characteristic of the imaging device is also called camera gamma. On the other hand, the gamma correction unit 113 is a display video gamma correction unit that performs gamma correction processing based on the gamma characteristic of the display device (display 116) on the video signal after the gamma correction processing by the gamma correction unit 109. . The gamma characteristic of the display device (display 116) is also called display gamma. Details of the gamma correction processing performed by the gamma correction units 109 and 113 will be described later.

  The luminance / color information detection unit 110 divides the image of the video signal subjected to the gamma correction processing by the gamma correction unit 109 into a horizontal direction and a vertical direction, thereby dividing a plurality of luminance / color information detection frames (hereinafter referred to as detection frames). Set). The luminance / color information detection unit 110 detects luminance information and color information for each detection frame by performing processing such as integration of the pixel values in the detection frame. The luminance information and color information for each detection frame detected by the luminance / color information detection unit 110 are sent to the camera microcomputer 111. Note that the microcomputer is an abbreviation for a microcomputer, and is similarly referred to as a microcomputer in the following description.

  The signal processing unit 112 performs various signal processes in addition to the white balance correction process, the edge enhancement process, the gamma correction process, and the luminance / color information detection process, but the description thereof is omitted. The video signal after various signal processing by the signal processing unit 112 is output and displayed on the external display 120 via the display 116 or the external I / F unit 119, or is displayed on the magnetic tape 115, the DVD disk 117, the memory card 118, or the like. Or recorded on a recording medium.

  The camera microcomputer 111 calculates the WB correction value for the WB correction processing and the edge enhancement correction value for the edge enhancement processing based on the luminance information and color information for each detection frame detected by the luminance / color information detection unit 110. The camera microcomputer 111 sends the WB correction value to the WB correction unit 107 and sends the edge enhancement correction value to the edge enhancement unit 108. As a result, the WB correction unit 107 performs WB correction processing based on the WB correction value, and the edge enhancement unit 108 performs edge enhancement processing based on the edge enhancement correction value.

  The camera microcomputer 111 sets a gamma correction curve for camera gamma in the gamma correction unit 109 and sets a gamma correction curve for display gamma in the gamma correction unit 113 based on the shooting mode and display mode of the video camera 201. Thus, the gamma correction unit 109 performs gamma correction processing using the camera gamma gamma correction curve, and the gamma correction unit 113 performs gamma correction processing using the display gamma correction curve. The shooting mode and display mode of the video camera 201 and the gamma correction curve and gamma correction processing set based on these modes will be described in detail later.

  In addition, the camera microcomputer 111 controls charge accumulation and readout in the image sensor 105 via the image sensor driving unit 106. The camera microcomputer 111 controls the focus and zoom of the lens 101 via the lens driving unit 103. The lens 101 is capable of manual focus as well as autofocus. The camera microcomputer 111 controls the aperture 102 via the aperture driver 104 and the image sensor 105 via the image sensor driver 106 based on the luminance information and color information for each detection frame by the luminance / color information detector 110. Control the exposure by controlling the shutter speed. When the video camera 201 has a camera shake correction function of any of the lens shift method, sensor shift method, and readout control method, the camera microcomputer 111 also controls camera shake correction according to these methods. The camera microcomputer 111 also controls the brightness (luminance) of the display 116. Details of the brightness control of the display 116 will be described later.

  The display 116 is composed of a liquid crystal display or the like, and displays an image being captured, an image reproduced from a recording medium, and the like. A touch panel (not shown) is also provided on the screen of the display 116, and the user can input various user instructions by touching the screen. Although not shown in FIG. 1, the video camera 201 also includes an operation unit including various keys, switches, dials, and the like that can be operated by the user. The external I / F unit 119 is an interface unit with an external device, and for example, an external display 120 or the like can be connected.

<Appearance structure of video camera>
FIG. 2 is a perspective view showing an overview of the video camera 201 of the present embodiment.
The lens unit 202 includes the lens 101 and the diaphragm 102 of FIG. The microphone 203 is provided for collecting sound during shooting. The speaker 210 is provided for outputting audio recorded together with the video when reproducing the video or the like. The battery 211 is a secondary battery that supplies power to the video camera 201 and is detachable from the main body. Inside the video camera 201, recording media such as a DVD disk 117, a magnetic tape 115, and a memory card 118 are accommodated so that video signals and still images can be recorded and reproduced.

  The moving image trigger switch 205 is a push button, for example, and is a switch operated by the user when transmitting user instructions for starting and ending moving image shooting to the device. The still image trigger switch 206 is, for example, a push button, and is a switch operated by the user when transmitting user instructions for starting and ending still image shooting to the device. The mode dial 207 is composed of a rotary switch. By operating the mode dial 207, the user switches the video camera 201 of the present embodiment to “reproduction” for setting the playback mode, “camera” for setting the camera mode, or “OFF” which is not any of them. be able to. The operation switch group 208 includes a switch for the user to operate the video camera 201, a key for inputting an image quality filter mode, a key for other menu operations, a reproduction system operation, and the like.

  An electronic viewfinder (EVF) 204 is provided for confirming, for example, whether or not a subject that is aimed at the time of shooting is reflected when the user looks in. The liquid crystal panel 209 is openable and closable with respect to the side of the main body of the video camera 201, and is also mounted so as to be able to rotate in the horizontal direction. It is also used for display. In the example of FIG. 2, the liquid crystal panel 209 is open with respect to the main body of the video camera 201. Note that the liquid crystal panel 209 is the display 116 in FIG. 1. For example, a touch panel is also provided, and a user interface (UI) by screen display and touch operation on the touch panel is also possible.

<Explanation of high brightness priority mode, normal shooting mode, and gamma characteristics>
In the video camera 201 of the present embodiment, at least a normal shooting mode, a high luminance priority mode, and various other shooting modes are prepared as shooting modes for shooting a video. The normal shooting mode is a mode in which the camera gamma set for the gamma correction unit 109 is set to the gamma characteristic for the normal shooting mode. In the high luminance priority mode, the camera gamma set for the gamma correction unit 109 is set to the gamma characteristic for the high luminance priority mode, and the brightness (luminance) of the display 116 is set to the maximum luminance. It is. In the camera mode, the video camera 201 of the present embodiment can be switched between the normal shooting mode and the high luminance priority mode in accordance with a selection input from the user.

  Hereinafter, the gamma characteristic for the normal shooting mode and the gamma characteristic in the high luminance priority mode in the present embodiment will be described with reference to FIGS. 3A and 3B show the gamma characteristic (camera gamma) of the imaging apparatus. FIG. 3C shows the gamma characteristic (display gamma) of the display device (display 116 in this embodiment). FIG. 3D shows the gradation characteristics when viewed as a total video processing system that combines the gamma characteristics of the imaging device and the gamma characteristics of the display device.

  First, the gamma characteristic (gamma correction curve) for the normal photographing mode will be described with reference to FIG. The normal shooting mode is a mode in which tone correction is performed by gamma correction processing including knee correction processing that compresses contrast in a medium to high luminance region while ensuring a practical input dynamic range. Note that the compression of contrast corresponds to reducing the slope of the characteristic curve represented by the dynamic range and the luminance. Here, the gamma characteristic 301 in FIG. 3A is a gamma characteristic corresponding to the case where the input dynamic range is x1, and ITU-R BT. This is a standard gamma characteristic standardized by 709 or the like. The gamma characteristic 303 for the normal shooting mode is a gamma characteristic corresponding to the case where the input dynamic range is x2, and is a characteristic in which the input dynamic range is expanded to a practical range with respect to the reference gamma characteristic 301. However, the gamma characteristic 303 for the normal photographing mode is a characteristic for compressing the contrast of the medium luminance region to the high luminance region as compared with the reference gamma characteristic 301. As described above, the gamma characteristic 303 for the normal shooting mode outputs an output (brightness) for an area from low luminance to medium luminance with high human visual sensitivity while expanding the input dynamic range as compared with the reference gamma characteristic 301. It is a characteristic to ensure. When the video camera 201 of the present embodiment is in the normal shooting mode, the gamma correction unit 109 sets the input value (input code value) of the luminance of the video signal as an output value (output code) corresponding to the gamma characteristic 303 for the normal shooting mode. Gamma correction processing such as conversion to (value).

  Next, the gamma characteristic (gamma correction curve) for the high luminance priority mode will be described with reference to FIGS. The gamma characteristic 302 for the high luminance priority mode shown in FIG. 3A is a gamma characteristic corresponding to the case where the input dynamic range is x2, and the input dynamic range is within a practical range with respect to the reference gamma characteristic 301. It has been extended to characteristics. For example, when a reference gamma characteristic 301 having an input dynamic range of x1 is represented by a function y = f (x) and the input dynamic range is expanded t times, the gamma characteristic 302 for the high-luminance priority mode is taken as an example. Can be expressed as a function of y = f (x / t). As described above, the gamma characteristic 302 for the high-luminance priority mode keeps the relationship of the output code with respect to the input code in accordance with the reference gamma characteristic 301, and allocates bits to code values from low luminance to high luminance. The ratio is fixed and not changed. The input dynamic range may be set as an appropriate value for each product of the imaging apparatus, or may be set as an appropriate value for each shooting mode within the same product. Further, the input dynamic range may be set adaptively for each shooting scene, for example, within the same shooting mode.

  When the video camera 201 of this embodiment is in the high luminance priority mode, the gamma correction unit 109 converts the input code value of the luminance of the video signal into an output code value corresponding to the gamma characteristic 302 for the high luminance priority mode. Gamma correction processing is performed. That is, in the high-luminance priority mode, the input dynamic range is expanded and the relationship between the input / output code values for all luminance regions from low luminance to high luminance is matched with the relationship between the input / output code values of the reference gamma characteristic 301. A gamma correction process using the characteristic 302 is performed. As described above, in the high luminance priority mode, the gamma correction processing using the gamma characteristic 302 that matches the relationship between the input and output code values of the reference gamma characteristic 301 is performed, and the high gamma characteristic 303 for the normal shooting mode is high. Contrast compression in the luminance area is not performed.

  On the other hand, in the case of the video camera 201 of the present embodiment, regardless of whether the shooting mode is the normal shooting mode or the high brightness priority mode, the initial setting gamma correction unit 113 has a display device as shown in FIG. A gamma correction process using the gamma characteristic 304 is performed. The gamma characteristic 304 in FIG. 3C is a reverse gamma characteristic corresponding to the gamma characteristic 302 for the high-luminance priority mode shown in FIG. Then, the gamma correction unit 113 performs gamma correction processing for converting the input code value of the luminance of the supplied video signal into a luminance value based on the gamma correction curve of the gamma characteristic 304 in FIG.

  For this reason, when the shooting mode is, for example, the high-luminance priority mode, the gamma correction unit 109 performs gamma correction processing using the gamma characteristic 302 shown in FIG. 3A, and the gamma correction unit 113 uses FIG. The gamma correction process using the gamma characteristic 304 is performed. FIG. 3B shows a gamma characteristic 302 used in the gamma correction unit 109 when the shooting mode is the high luminance priority mode. Therefore, when the shooting mode is the high-luminance priority mode, the gamma correction processing is performed by the gamma characteristic 302 in FIG. 3B and the gamma characteristic 304 in FIG. Becomes a gradation characteristic 305 as shown in FIG. That is, the gradation characteristic 305 in FIG. 3D is linear in the entire luminance region from the low luminance part to the high luminance part. In this case, the image displayed on the display 116 is a natural image in which the natural gradation, color, and sharpness of the actual subject are reproduced. For example, the brightness of the metal, the transparency of water, the stereoscopic effect of the blue sky and clouds, Gradation such as skin tone, color reproducibility, and sharpness are greatly improved.

<View assist mode and waveform monitor display mode settings>
Furthermore, the video camera 201 of the present embodiment is configured to change the brightness (brightness) setting of the display 116 depending on whether the shooting mode is the normal shooting mode or the high luminance priority mode. Specifically, the camera microcomputer 111 controls to change the brightness of the display 116 between the normal shooting mode and the high luminance priority mode. In addition, the video camera 201 according to the present embodiment can display various types of shooting assist displays such as a view assist mode and a waveform monitor display mode, which will be described later, in accordance with user input in both the normal shooting mode and the high brightness priority mode. The mode can be set. The video camera 201 according to the present embodiment performs setting of a view assist mode, setting of a waveform monitor display mode, and the like in accordance with, for example, a touch input operation by a user on a touch panel provided on the display 116.

  In the present embodiment, the view assist mode and the waveform monitor display mode are, for example, shooting assist display when the exposure is set by checking whether the brightness of the shot image is appropriate at the time of shooting the image. It is prepared as an available mode. When the view assist mode is set to ON in the normal shooting mode, the display brightness of the display 116 is set to the maximum brightness. On the other hand, in the high luminance priority mode, the display luminance of the display 116 is set to the highest luminance as described above. For this reason, when the setting of the view assist mode is ON in the high luminance priority mode, the display gamma set in the gamma characteristic 304 of FIG. 3C is a low to medium luminance (low / medium luminance) region. The gamma characteristic is changed to increase the display brightness. When the waveform monitor display mode setting is on, waveform information representing signal components (for example, luminance components and color components) included in the captured video is generated, and the waveform is set in the screen together with the captured video. Overlaid on top. Further, when the setting of the waveform monitor display mode is on in the normal photographing mode, the display brightness of the display 116 is set to the maximum brightness. On the other hand, when the setting of the waveform monitor display mode is on in the high luminance priority mode, the display gamma set in the gamma characteristic 304 of FIG. 3C is low as in the case of the view assist mode. The gamma characteristic is changed so as to increase the display luminance in the middle luminance region.

  As described above, the video camera 201 according to the present embodiment displays the display gamma in the low / medium luminance area when the setting of one or both of the view assist mode and the waveform monitor display mode is on in the high luminance priority mode. Change the gamma characteristics to increase the display brightness. In this case, the display gamma is changed by the camera microcomputer 111 changing and controlling the gamma characteristic of the gamma correction unit 113. Note that the display gamma change by the camera microcomputer 111 may be automatically performed when either one or both of the view assist mode and the waveform monitor display mode are turned on, or a change instruction from the user. May be performed when is input.

  Further, in the video camera 201 of this embodiment, when both the view assist mode and the waveform monitor display mode are set to OFF (OFF), the shooting mode is either the normal shooting mode or the high brightness priority mode. The power saving mode can be set to “valid”. On the other hand, in the video camera 201, when one or both of the view assist mode and the waveform monitor display mode are set to ON (ON), the shooting mode is either the normal shooting mode or the high brightness priority mode. Also set the power saving mode to “invalid”.

  FIGS. 4A and 4B show the brightness (luminance) of the display 116 and the gamma set in the gamma correction unit 113 when the shooting mode is the normal shooting mode and the high luminance priority mode. Characteristics (display gamma). 4A and 4B also show the power saving mode setting (valid or invalid setting) and the power consumption of the video camera 201. FIG. FIG. 4A shows an example in which both the view assist mode and the waveform monitor display mode are set to OFF. FIG. 4B shows an example in which either one or both of the view assist mode and the waveform monitor display mode are set to ON. In addition, each numerical value of the brightness | luminance of FIG. 4 (a) and FIG.4 (b), power consumption, and a gamma correction value is an example.

  As shown in FIG. 4A, when both the view assist mode and the waveform monitor display mode are set off, the power saving mode can be effectively set in both the normal photographing mode and the high brightness priority mode. However, in the high luminance priority mode, the brightness of the display 116 is set to the highest luminance value as described above. In addition, the gamma characteristic (display gamma) of the gamma correction unit 113 at this time is the same value in the normal shooting mode and the high luminance priority mode, and is the gamma characteristic 304 described with reference to FIG.

  On the other hand, as shown in FIG. 4B, when either one or both of the view assist mode and the waveform monitor display mode are set, the camera microcomputer 111 selects either the normal shooting mode or the high brightness priority mode. The power saving mode is also set to “invalid” in FIG. When one or both of the view assist mode and the waveform monitor display mode are set to ON, as shown in FIG. 4B, in the normal shooting mode, the brightness of the display 116 is, for example, the highest luminance. Set to a value. On the other hand, in the high brightness priority mode, the brightness of the display 116 is already set to the maximum brightness in the setting state of FIG. 4A, and therefore the brightness of the display 116 is the highest in the example of FIG. This is the luminance value.

  Here, in the high brightness priority mode, the gradation characteristic of the total video processing system is a linear characteristic as described with reference to FIGS. 3B to 3D described above. The displayed video is a video having a low low and medium luminance range when viewed from the user. In other words, because the human eye is sensitive to the low and medium luminance range, when an image with linear gradation characteristics is displayed, the low and medium luminance appears as a dark image, resulting in an image with low visibility for the user. Become.

  For this reason, in the high brightness priority mode, when one or both of the view assist mode and the waveform monitor display mode are set, the camera microcomputer 111 sets the display gamma and the display brightness in the low / medium brightness region. Change to gamma characteristics to increase. Specifically, the camera microcomputer 111 changes the display gamma of the gamma correction unit 113 from the previously set gamma characteristic 304 shown in FIG. 3C to a low / medium luminance region as shown in FIG. Is changed to a gamma characteristic 306 that increases the display luminance of the image. FIG. 4C also shows a default gamma characteristic 304 for comparison with the gamma characteristic 306 that increases the display luminance in the low-medium luminance region.

  As described above, when the display gamma is changed to the gamma characteristic 306 that increases the display brightness in the low / medium brightness area, the video displayed on the display 116 is viewed from the user whose display brightness in the low / medium brightness area is increased. The video is highly visible. Therefore, in this case, the user can determine whether or not the exposure at the time of shooting is appropriate while viewing the video, and can set the correct exposure.

  In the description of FIGS. 4A to 4C, the view assist mode and the waveform monitor display mode in the high luminance priority mode are given as examples. In addition, the following various shooting assist display modes are provided. In this case, the above-described change control to the gamma characteristic 306 may be performed. For example, a peaking display mode, a zebra pattern display mode, a histogram display mode, and an exposure setting display mode can be considered as the photographing assist display mode when the change control to the gamma characteristic 306 is performed. The peaking display mode is a function for performing predetermined characterization display (for example, coloring display) on the outline of the focused area or the like when performing focus adjustment (for example, manual focus) while viewing the display 116. It is. If the display brightness of the display 116 can be increased in the peaking display mode, the user can easily confirm whether or not the focus is achieved. The zebra pattern display mode is a mode for displaying a predetermined pattern image (for example, a zebra pattern) in an arbitrarily set luminance area, for example. If the display brightness of the display 116 can be increased in the zebra pattern display mode, the user can easily confirm whether or not a desired area in the captured video has the set brightness. The histogram display mode is a mode for displaying histograms of luminance and color signal components of a captured video. If the display brightness of the display 116 can be increased in the histogram display mode, the user can easily confirm whether or not the brightness and color in the captured video are the desired brightness and color. Note that the histogram display may be superimposed and displayed on a predetermined area set in the screen together with the captured video, similarly to the waveform monitor display described above. The exposure setting display mode is a mode in which, for example, when a setting for changing the exposure is performed, a captured image of the set exposure is displayed on the display. If the display brightness of the display 116 can be increased in the exposure setting display mode, the user can easily confirm whether or not the captured image has a desired exposure.

<Flow of luminance gradation correction processing when shooting video with a video camera>
In FIG. 5, in the video camera 201 of the present embodiment, the camera microcomputer 111 controls tone correction processing from determination of an input dynamic range at the time of video shooting to determination of a gamma correction curve, generation of metadata, and gamma correction processing. It is a flowchart which shows the flow at the time. Each process of the flowchart of FIG. 5 is realized by the camera microcomputer 111 executing the video processing program according to the present embodiment and controlling each unit. The video processing program according to the present embodiment may be prepared in advance in a ROM (not shown) of the video camera 201, or may be read from an external storage medium (not shown) and loaded into a RAM (not shown). Good. In addition, the video processing program may be downloaded to the video camera 201 from a network such as the Internet. Each process of the signal processing unit 112 may be realized by a CPU or the like executing a video processing program. In this case, the CPU executes each process according to the flow shown in the flowchart of FIG. In the following description, steps S401 to S408 of each process in FIG. 5 are abbreviated as S401 to S408.

  The gradation correction processing at the time of video shooting shown in the flowchart of FIG. 5 is started when, for example, the moving image trigger switch 205 or the still image trigger switch 206 is operated by the user to start shooting. When the gradation correction processing of the video camera 201 starts, the camera microcomputer 111 determines the input dynamic range in S401. The input dynamic range determined at this time is a predetermined value set in advance according to the shooting mode, or calculated based on luminance information and color information detected for each detection frame by the luminance / color information detection unit 110. Value. After S401, the camera microcomputer 111 advances the process to S402.

  In step S <b> 402, the camera microcomputer 111 performs exposure by controlling the aperture 102 and controlling the shutter speed of the image sensor 105 based on the luminance information and color information detected for each detection frame by the luminance / color information detection unit 110. Take control. After S402, the camera microcomputer 111 advances the process to S403.

  In S403, the camera microcomputer 111 determines whether or not the shooting mode is set to the high luminance priority mode. Specifically, the camera microcomputer 111 operates the mode dial 207 described above to see whether the mode is set to the high brightness priority mode or the normal shooting mode, so that the shooting mode is set to the high brightness priority mode. Determine whether it is set. If the camera microcomputer 111 determines in S403 that the shooting mode is set to the high-luminance priority mode, the camera microcomputer 111 proceeds to S404 and determines that the high-luminance priority mode is not set (the normal shooting mode). If so, the process proceeds to S406.

  When the process proceeds from S403 to S404, the camera microcomputer 111 determines the gamma characteristic used for the gamma correction process of the gamma correction unit 109 as the gamma correction curve of the gamma characteristic 302 for the high-luminance priority mode described above in S404. To do. After S404, the camera microcomputer 111 advances the process to S405.

  In S405, the camera microcomputer 111 generates metadata to be described later corresponding to the high luminance priority mode and adds it to the video signal. The addition of the metadata is performed, for example, at the subsequent stage of the gamma correction unit 109, but the illustration of the configuration for adding the metadata to the video signal is omitted. As a result, the metadata corresponding to the high luminance priority mode is then recorded on the magnetic tape 115, the DVD disk 117, the memory card 118, and the like together with the video signal. After S405, the camera microcomputer 111 advances the process to S408.

  Here, the metadata is displayed when an image captured by the video camera 201 of the present embodiment is displayed on an external display device (external display 120 or the like) or displayed on an external display device via a recording medium or the like. In addition, it is information used for proper display on an external display device. Specifically, the metadata corresponding to the high luminance priority mode includes a flag indicating the high luminance priority mode, an input dynamic range, a magnification and a peak luminance value with respect to a preset reference value of display luminance, and a gamma shape of the camera gamma. Information such as information and base gamma is included. The information indicating the input dynamic range is information used when calculating an appropriate brightness (peak luminance value) by an external display device, for example. The magnification of the display luminance with respect to the reference value is “t” (the reference input dynamic range x1 is increased t times) when the gamma characteristic 302 of the function y = f (x / t) described above is set in the high luminance priority mode. This is information corresponding to “t times” when spread. When the input dynamic range x1 as a reference in the high brightness priority mode is expanded t times, it is appropriate to increase the display brightness on the external display device to t times. Be prepared. The peak luminance value is ITU-R BT. This value is calculated by the camera microcomputer 111 based on the peak luminance value determined as the standard on the display device side in 709. The camera microcomputer 111 calculates an appropriate peak luminance value for the display device according to the input dynamic range, and includes the peak luminance value as one piece of metadata. The gamma shape information is information indicating a mathematical expression and a gamma value for representing the shape of the gamma correction curve, and is information representing the shape of the gamma characteristic 302 for the high luminance priority mode. Base gamma is ITU-R BT. This is information indicating the above-described gamma characteristic 301 standardized in 709.

  When the process proceeds from S403 to S406, the camera microcomputer 111 determines the gamma characteristic used for the gamma correction processing of the gamma correction unit 109 as the gamma correction curve of the gamma characteristic 303 for the normal shooting mode described above in S406. . After S406, the camera microcomputer 111 advances the process to S407.

  In S407, the camera microcomputer 111 adds metadata corresponding to the normal shooting mode to the video signal. The metadata corresponding to the normal shooting mode includes information such as a flag indicating the normal shooting mode, an input dynamic range, a magnification and a peak luminance value with respect to a preset reference value of display luminance, gamma shape information of camera gamma, base gamma, and the like. Become. The input dynamic range, the magnification with respect to the preset reference value of display luminance, the peak luminance value, the base gamma, and the like are the same data as in the high luminance priority mode. The gamma shape information is information representing the shape of the gamma characteristic 303 for the normal shooting mode. The addition of metadata corresponding to the normal shooting mode is performed after the gamma correction unit 109 (not shown) as in the case of S406 described above. As a result, the metadata corresponding to the normal shooting mode is then recorded on the magnetic tape 115, the DVD disk 117, the memory card 118, and the like together with the video signal. After S407, the camera microcomputer 111 advances the process to S408.

  In step S408, the camera microcomputer 111 performs gamma correction based on the gamma correction curve for the high brightness priority mode determined in step S404 or the gamma correction curve for normal shooting determined in step S406. Let the process do. After the gamma correction process of S408, the camera microcomputer 111 repeats the process of the flowchart of FIG. 5 until video shooting by the video camera 201 is completed.

  FIG. 6 is a flowchart showing a flow when the camera microcomputer 111 controls the brightness and display gamma settings of the display 116 according to the settings of the high brightness priority mode, the view assist mode, and the waveform monitor display mode in the camera mode. It is. Each process of the flowchart of FIG. 6 is realized by the camera microcomputer 111 executing the video processing program according to the present embodiment and controlling each unit. Also in this case, the video processing program may be read from a ROM (not shown) or an external storage medium of the video camera 201 and loaded into a RAM or the like, or may be downloaded to the video camera 201 from a network such as the Internet. Further, when each process of the signal processing unit 112 is realized by executing a video processing program by the CPU or the like, the CPU executes each process according to the flow shown in the flowchart of FIG. In the following description, steps S501 to S506 of each process in FIG. 6 are abbreviated as S501 to S506.

  The process shown in the flowchart of FIG. 6 is started when the camera mode is set by the mode dial 207 of FIG. 2 and the live view display for displaying the photographed image being photographed on the display 116 is performed. When the processing of the flowchart of FIG. 6 starts, the camera microcomputer 111 determines in S501 whether or not the shooting mode of the video camera 201 is set to the high luminance priority mode. Specifically, the camera microcomputer 111 can store shooting mode setting information in an internal RAM, and determines whether or not the high luminance priority mode is set based on the shooting mode setting information. If the camera microcomputer 111 determines in S501 that the high brightness priority mode is set, the process proceeds to S502, and if it is determined that the high brightness priority mode is not set, the process proceeds to S506.

  When the process proceeds from S501 to S502, the camera microcomputer 111 determines whether or not the above-described view assist mode setting is on. Specifically, the camera microcomputer 111 holds camera mode setting information in an internal RAM, and determines whether or not the view assist mode setting is on based on the camera mode setting information. If the camera microcomputer 111 determines in S502 that the setting of the view assist mode is on, the process proceeds to S504, and if it is determined that the setting of the view assist mode is off, the process proceeds to S503.

  When the processing proceeds to S503, the camera microcomputer 111 determines whether the setting of the waveform monitor display mode described above is on. Specifically, the camera microcomputer 111 determines whether the setting of the waveform monitor display mode is on based on the setting information of the camera mode stored in the internal RAM. If the camera microcomputer 111 determines in S503 that the setting of the waveform monitor display mode is on, the process proceeds to S504, and if it is determined that the setting of the waveform monitor display mode is off, the process proceeds to S506. .

  When the process proceeds from S502 or S503 to S504, that is, when one or both of the view assist mode and the waveform monitor display mode are set to ON, the camera microcomputer 111 is displayed on the screen of the display 116 as shown in FIG. The UI screen 600 is displayed. A UI screen 600 shown in FIG. 7 is an example of a user interface (UI) screen that displays a message or the like to the user and that can accept a user input operation via a touch panel arranged on the screen of the display 116. is there. On the UI screen 600, a message 601 asking the user whether to increase the brightness of the display 116, and buttons 602 and 603 for receiving a touch input operation when the user instructs whether to increase the brightness of the display 116. Is displayed. Note that the “view assist mode” described in the message 601 has a slightly different meaning from the view assist mode in the camera mode of the present embodiment, and is an expression for confirming to the user whether to increase the brightness of the display 116. It is used as. The button 602 is a button icon that is touch-operated by the user when the brightness of the display 116 is increased, and the button 603 is a button icon that is touch-operated by the user when the brightness of the display 116 is not increased. . In step S <b> 504, the camera microcomputer 111 determines whether the user has performed a touch input operation on the UI screen 600 with respect to the button 602 or the button 603. If the camera microcomputer 111 determines in S504 that a touch input operation to the button 602 has been performed, that is, if a user instruction input operation to increase the brightness of the display 116 is performed, the process proceeds to S505. On the other hand, if the camera microcomputer 111 determines in S504 that a touch input operation to the button 603 has been performed, and if a user instruction input operation that does not increase the brightness of the display 116 is performed, the process proceeds to S506.

  When the processing proceeds to step S505, the camera microcomputer 111 increases the gamma characteristic (display gamma) of the gamma correction unit 113 to increase the display luminance in the low / medium luminance region as described with reference to FIG. Change to After the process of S505, the camera microcomputer 111 ends the process of the flowchart of FIG.

  When the process proceeds to S506, that is, when the shooting mode is the normal shooting mode, or when the settings of both the view assist mode and the waveform monitor display mode are OFF in the high brightness priority mode, the camera microcomputer 111 determines the brightness of the display 116. Set to normal brightness. The normal set brightness is the brightness set as described above with reference to FIG. 4A or the brightness in the normal shooting mode shown in FIG. 4B.

  In the video camera 201 of the present embodiment, for example, when a captured image in the high brightness priority mode is displayed on the display 116 in the shooting assist display mode such as the view assist mode or the waveform monitor display mode, the low and medium brightness is displayed. The Therefore, according to the video camera 201 of the present embodiment, when a captured image is displayed, it is possible to display an image with high visibility for the user, and the user can easily confirm the gradation of the low and medium luminance regions. It becomes.

<Other embodiments>
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

  105 Image sensor, 109, 116 Gamma correction unit, 110 Luminance / color information detection unit, 111 Camera microcomputer, 112 Signal processing unit, 116 Display

Claims (13)

When displaying an image based on a video signal being shot on a display device, the video signal after correction processing using a predetermined gamma characteristic is corrected using a first gamma characteristic corresponding to the predetermined gamma characteristic. Correction means for performing processing;
In a case where a predetermined shooting assist display is performed when displaying an image based on a video signal being shot on the display device, a display brightness of the display device is set higher than that of the first gamma characteristic. Control means for performing gamma correction by the gamma characteristic of 2;
A video processing apparatus comprising: The correction means is a display video correction means for performing correction processing on a video signal displayed on the display device,
Switching between the predetermined gamma characteristic and a gamma characteristic different from the predetermined gamma characteristic is possible, and a correction process for the video signal being shot is performed based on the switched gamma characteristic. Further comprising means,
The control means performs correction processing based on the predetermined gamma characteristic on the video signal being shot by the correction means for the shot video, and causes the display device to display a video based on the video signal being shot. 2. The video processing according to claim 1, wherein when the predetermined shooting assist display is performed, the correction unit for the display video performs gamma correction based on the second gamma characteristic. apparatus. The predetermined gamma characteristic indicates the relationship between the input value and the output value in the entire luminance region from low luminance to high luminance of the video signal, regardless of the input dynamic range of the video signal. It is a gamma characteristic that matches the relationship between the input value and output value in the characteristic.
The video processing apparatus according to claim 1, wherein the first gamma characteristic is a gamma characteristic opposite to the predetermined gamma characteristic.   4. The video processing apparatus according to claim 3, wherein the second gamma characteristic is a gamma characteristic that increases display luminance in a region having a lower luminance to a middle luminance than the first gamma characteristic.   The control means sets the display brightness of the display device to a maximum brightness regardless of whether or not the predetermined shooting assist display is performed when displaying a video based on the video signal being shot on the display device. The video processing apparatus according to claim 4, wherein:   The video processing apparatus according to claim 1, wherein the predetermined photographing assist display is performed in response to an input of a user instruction for brightening the display on the display device.   7. The video processing apparatus according to claim 1, wherein the predetermined photographing assist display includes a waveform monitor display that displays waveform information representing a signal component of the video signal being photographed. .   8. The predetermined photographing assist display includes a peaking display for performing a predetermined characterization display on a focused area in an image based on the photographing video signal. The video processing device according to any one of the above.   The predetermined photographing assist display includes a pattern display for displaying a predetermined pattern image in a predetermined luminance area in the video based on the video signal being photographed. The video processing apparatus according to any one of claims 8 to 9.   The video processing apparatus according to claim 1, wherein the predetermined shooting assist display includes a histogram display that displays a histogram of signal components of the video signal being shot.   The predetermined photographing assist display includes an exposure setting display for displaying an image based on a video signal photographed at the set exposure when an exposure change is set during the photographing. Item 11. The video processing device according to any one of Items 1 to 10. A video processing method executed by a video processing apparatus that processes a video signal,
In a case where a predetermined shooting assist display is performed when displaying an image based on the video signal being shot on the display device, the predetermined gamma is applied to the video signal that has been subjected to correction processing using a predetermined gamma characteristic. A video processing method comprising: performing a correction process using a second gamma characteristic that increases the display brightness of the display device more than the first gamma characteristic corresponding to the characteristic.   The program for functioning a computer as each means of the video processing apparatus of any one of Claims 1 thru | or 11.

Images