JP2018056611A - Image processing device and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device and a display device that can perform optimum gamma correction and that can perform image displaying on a small monitor attached to a camera body, for each image recorded in a wide dynamic range.SOLUTION: An imaging device comprises reproduction means that reproduces and displays a recorded video image on display means, dynamic range acquisition means that acquires meta-data from the recorded video image and acquires dynamic range information of the recorded video image from the acquired meta-data, and gamma correction means that performs gradation correction by changing a gamma characteristic of the display means. The gamma correction means performs the gradation correction of a middle tone part of the display means by means of dynamic range information acquired by the dynamic range acquisition means, and further comprises white balance changing means that corrects deviation of chromaticity due to a dynamic range difference.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an imaging device and a display device for imaging a subject.

  In recent years, the performance of image / video output devices has improved, and televisions and displays capable of expressing a wide dynamic range close to real subjects have been developed. In view of this, a technology is being developed in which a wide dynamic range captured by a camera in a video production or television development field can be directly applied to a video signal. Along with this, the spread of cameras capable of shooting with a wide dynamic range is increasing. Specifically, a medium luminance to high luminance region compressed and recorded is recorded linearly without being compressed. In order to display an image captured in such a wide dynamic range, a large monitor having a high peak luminance and a wide dynamic range with high contrast is required.

  However, since the small monitor attached to the camera body has a narrow dynamic range, when the luminance linear image is displayed, the entire screen becomes dark. Therefore, a small monitor attached to the camera body has been proposed to ensure visibility by performing gamma correction to raise the halftone and increasing the brightness in the case of wide dynamic range recording (see Patent Document 1).

JP 2007-228048 A

  However, in the above conventional example, when recording with a wide dynamic range, the optimum gamma correction is performed according to the recorded dynamic range, but when reproducing, the recording was performed with a different dynamic range by another camera. It is also possible to reproduce an image, and it is difficult to perform optimal gamma correction.

  An object of the present invention is to provide an imaging device and a display device that can perform optimal gamma correction for each image recorded in a wide dynamic range and display an image on a small monitor attached to the camera body.

In order to achieve the above object, a display device according to the present invention includes:
An apparatus main body; display means for displaying video; playback means for playing back and displaying recorded video on the display means; dynamic range determination means for detecting metadata from the recorded video and determining a dynamic range of the recorded video; and the display Gamma correction means for performing gradation correction by changing the gamma characteristic of the means, and the gamma correction means uses the dynamic range information determined by the dynamic range determination means to enable the gradation of the halftone portion of the display means Correction is performed.

  According to the display device of the present invention, even when an image recorded with a different wide dynamic range is reproduced, the optimum gamma is obtained for each image recorded with a wide dynamic range by acquiring dynamic range information of metadata. The image can be displayed on a small monitor attached to the camera body after correction.

It is a block diagram which shows the structure of the imaging device in the Example of this invention. It is a block diagram which shows the structure of the imaging device in the Example of this invention. It is a flowchart figure explaining the operation | movement in the Example of this invention. It is a figure explaining the dynamic range in the Example of this invention. It is a figure explaining the gamma characteristic in the Example of this invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
<Embodiment of the present invention>
A system control configuration of the imaging apparatus according to the embodiment of the present invention will be described. FIG. 1 is a circuit block diagram for explaining a system control configuration in a video camera according to an embodiment of the present invention. A power switch 112, an operation switch 113, a liquid crystal display unit 105, and a memory 114 are connected to the system control unit 101.

  The power switch 112 is a change-over switch for turning on / off the power of the camera. The operation switch 113 is a switch for operating the camera. The liquid crystal display unit 105 includes a liquid crystal panel 107 capable of displaying captured video and playback video, a touch panel 106 disposed on the front surface of the liquid crystal panel 107, and a backlight 108 that irradiates the liquid crystal panel 107 from the back side. The touch panel 106 detects menu operation and playback operation for setting the video camera on the display screen, and position information touched on the screen by the user. The system control unit 101 controls the luminance of the backlight 108 via the power supply circuit 109 that controls the current of the backlight 108.

  The video / audio input unit 102 includes an imaging unit that converts a subject optical image from the lens into an image signal and outputs a video signal in a predetermined format, and an audio input unit such as a microphone that inputs audio. The video / audio signal processing unit 103 performs various signal processing such as noise reduction processing and AGC for controlling the signal level to be constant on the video signal from the video / audio input unit 102. The analog signal subjected to these processes is converted into a digital signal by an A / D converter (not shown) and supplied to the digital signal processor 110.

  The digital signal processing unit 110 performs format conversion, resizing processing, and OSD superposition on the signal from the video / audio signal processing unit 103 and supplies the signal to the panel signal processing unit 111. When the photographer performs a recording operation, the system control unit 101 transfers the video / audio signal from the digital signal processing unit 110 to the recording / reproducing unit 104 and records it on a recording medium (not shown). The metadata generation unit 115 inputs the dynamic range information of the video recorded in the video data recorded on the recording medium as metadata. The memory 114 is built in the video camera and temporarily records data when the digital signal processing 110 performs processing. The panel signal processing unit 111 performs signal processing described later on the video signal supplied to the liquid crystal panel 107.

  Next, the panel signal processing 111 will be described. FIG. 2 shows a block diagram of the panel signal processing circuit. The Gain / sharpness correction unit 201 performs a gain adjustment for adjusting a signal level and a sharpness correction process for edge enhancement for a luminance signal (Y signal). The Gain / color correction unit 202 performs gain adjustment, color correction processing for adjusting saturation and hue on the color difference signal (Cb / Cr signal).

  The matrix circuit 203 converts the luminance signal and the color difference signal into RGB signals by one-dimensional matrix calculation processing. The gamma correction unit 204 performs gamma correction on the RGB signals. For gamma correction, gradation conversion is performed using an LUT (Look Up Table) indicating stored gamma characteristics. The WB correction unit 205 performs white balance correction by performing bright correction processing and contrast correction processing on each of the RGB signals.

  Next, the operation of the video camera in the embodiment of the present invention will be described. Hereinafter, a method for performing an optimum gamma correction for each image recorded in a wide dynamic range in an imaging apparatus and a display apparatus for imaging a subject in an embodiment of the present invention will be described with reference to flowcharts and diagrams.

  FIG. 3 is a flowchart illustrating the operation of the imaging apparatus according to the embodiment. By operating the power switch 112, power is supplied to the video camera. The operation switch 113 is operated to set the reproduction mode. In S301, the touch panel 106 is operated from the reproduction image list displayed on the liquid crystal display unit 105, a reproduction image is selected, and the recording / reproduction unit 104 starts reproduction. In step S302, the system control unit 101 acquires metadata from the reproduction image data. In step S303, dynamic range information is acquired from the metadata acquired by the system control unit 101.

  The dynamic range information will be described with reference to FIG. FIG. 4 shows camera gammas with different dynamic ranges. Standard photography BT. 709 is a normal BT. Up to 118% of the subject brightness of the camera input with the 709 gamma characteristic is stored in the IRE 109 and displayed on the display monitor in a linear brightness manner. Wide dynamic range shooting mode BT. 709 (300%) is a gamma characteristic stored in the IRE 109 so that a subject luminance of up to 300% can be displayed linearly. Wide dynamic range shooting mode BT. 709 (400%) is a gamma characteristic stored in the IRE 109 so that the subject brightness of up to 400% can be displayed linearly.

  The subject luminance (%) for wide dynamic range shooting varies depending on the video camera. The video camera inputs dynamic range information as metadata during recording. The subject luminance (%) which is the camera input range is input to the dynamic range information of the metadata. In S304, based on the dynamic range information acquired by the system control unit 101, the luminance of the backlight 108 is controlled via the power supply circuit 109 that controls the current of the backlight 108. Specifically, when the dynamic range is 300% or 400%, the luminance of the backlight 108 is increased.

  When shooting with a wide dynamic range of 300% or 400%, the normal BT. Since it is darker than 709 gamma, it is necessary to increase the luminance on the monitor side. In S305, the panel signal processing unit 111 performs gamma correction based on the dynamic range information acquired by the system control unit 101.

  FIG. 5 shows a gamma correction LUT of the liquid crystal panel 107. BT. 709 is a camera gamma BT. It has the characteristic of inverse gamma γ2.2 of 709, and is displayed in luminance linear. BT. 709 (300%) is BT. In contrast to 709, in order to ensure visibility, the brightness is increased by raising the halftone. The small monitor attached to the video camera body has a low maximum brightness and a narrow dynamic range. Since the luminance equivalent to 709 cannot be obtained, the gamma correction is performed with emphasis on visibility.

  BT. 709 (400%) is BT. Since the halftone becomes darker than 709 (300%), the halftone is raised to increase the luminance, and conversely, on the high gradation side, the gamma is lowered to widen the gradation expression. The gamma correction unit 204 stores an LUT for each gamma characteristic, and the system control unit 101 performs gamma correction by replacing the LUT based on the dynamic range information.

  In step S306, the WB correction unit 205 performs white balance correction on the chromaticity shift due to the difference in the dynamic range using the LUT based on the dynamic range information acquired by the system control unit 101.

  As described above, according to the imaging apparatus of the present embodiment, even when an image recorded with a different dynamic range is reproduced by another camera, it is recorded with a wide dynamic range by acquiring dynamic range information of metadata. Optimal gamma correction can be performed for each image, and the image can be displayed on a small monitor attached to the camera body.

  Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. A part of the above-described embodiments may be appropriately combined.

101 system control unit, 102 video / audio input unit, 103 video / audio signal processing unit, 104 recording / playback unit, 105 liquid crystal display unit, 106 touch panel, 107 liquid crystal panel, 108 backlight, 109 power supply circuit, 110 digital signal processing unit , 111 panel signal processing unit, 112 power switch, 113 operation switch, 114 memory, 115: metadata generation unit, 201 Gain / sharpness correction unit, 202 Gain / color correction unit, 203 matrix circuit, 204 gamma correction unit, 205 WB Correction unit

Claims (4)

The device body;
Display means for displaying images;
Playback means for playing back and displaying recorded video on the display means;
Dynamic range determination means for detecting metadata from the recorded video and determining the dynamic range of the recorded video;
Gamma correction means for performing gradation correction by changing the gamma characteristic of the display means,
The display device, wherein the gamma correction unit performs gradation correction of a halftone portion of the display unit based on the dynamic range information determined by the dynamic range determination unit. A white balance changing means for changing the white balance of the display means;
The display device according to claim 1, wherein the white balance changing unit changes the white balance of the display unit based on the dynamic range information determined by the dynamic range determining unit. The display device according to claim 1, wherein the gamma correction unit performs gradation correction of a high gradation part of the display unit based on the dynamic range information determined by the dynamic range determination unit. 2. The display device according to claim 1, wherein the recorded video is recorded with a camera gamma characteristic in which an input / output characteristic is linear without compressing a part of contrast.