JP2019113654A - Image processing device - Google Patents

Abstract

To provide an image processing device which can reduce the power consumption by changing the light emission intensity of a subpixel of white in accordance with the temperature of display means when in an HDR assist mode.SOLUTION: An image processing device includes: imaging means; display means in which color pixels containing subpixels of red, green, blue and white are arranged; light emission luminance control means which can control the light emission luminance of the display means; intensity control means which can change the light emission intensity of the subpixel of white; temperature detection means which detects the temperature of the display means; and HDR assist mode detection means which detects whether being in the HDR assist mode or not. The image processing device, when in the HDR assist mode, makes the intensity set to the intensity control means the first set value when the temperature detected by the temperature detection means is higher than a threshold, and makes the set value set to the intensity control means the second set value having the intensity smaller than the intensity set with the first set value when the detected temperature is lower than the threshold.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image processing apparatus provided with display means.

  In recent years, imaging devices capable of generating captured image data (image data representing an image of a subject) having a wide dynamic range by imaging are increasing. A wide dynamic range is called "High Dynamic Range (HDR)" or the like, and image data having HDR is called "HDR image data" or the like. And in the field of image production, development of an apparatus (an image processing apparatus, a display apparatus, etc.), the opportunity where HDR image data is assumed is increasing.

  In order to display an image faithful to HDR image data, a high precision display device is required. For example, a display device capable of displaying a display image (image displayed on the screen) having a high upper limit of display luminance (luminance on the screen) and high contrast and capable of displaying a display image having a wide dynamic range Is required. Hereinafter, a display device capable of displaying an image faithful to HDR image data will be referred to as “HDR display device”.

For example, a display device which satisfies the condition that the maximum display luminance is 1000 nits (= 1000 cd / m ² ) or more and the minimum display luminance is 0.03 nits or less may be defined as the HDR display device. In addition, a liquid crystal display device satisfying the condition that the maximum display luminance is 1000 or more and the minimum display luminance is 0.05 or less may be defined as the HDR display. A self-luminous display (such as an organic EL display) satisfying the condition that the maximum display luminance is 540 nits or more and the minimum display luminance is 0.0005 nits or less may be defined as the HDR display device.

  By the way, even in the case of the HDR display device having the maximum display luminance of 1000 nits or more, the power consumption is significantly increased when the high luminance display of 1000 nits or more is performed, and therefore the reduction of the power consumption is required.

  Thus, for example, Patent Document 1 is disclosed. This is an RGBW pixel panel in which white (W) sub-pixels (hereinafter, W pixels) are added to conventional red (R), green (G), and blue (B) sub-pixels (hereinafter, RGB pixels) . Since this panel can achieve high luminance, power reduction can be realized by reducing the luminance of the backlight.

  Here, RGB pixels mean one color pixel composed of R sub-pixel, G sub-pixel and B sub-pixel. Also, RGBW pixels mean one color pixel composed of R sub-pixel, G sub-pixel, B sub-pixel and W sub-pixel. A plurality of sub-pixels (dots) constitute one pixel (pixel).

  However, in the RGBW pixel panel, although it is possible to improve the luminance by using the W pixel, the luminance is reduced in the case of monochrome display without using the W pixel. As a result, when white and a single color are displayed, the relative luminance of the single color with respect to the white is low, and image quality deterioration occurs in which the single color becomes a dull image. In addition, when the luminance ratio between the W pixel and the RGB pixel is increased, the W pixel can be easily seen, and thus the image quality may be deteriorated such that the dot is noticeable. In particular, when a white area exists in the area surrounded by the high saturation area (black frame portion), the image quality is significantly deteriorated.

Unexamined-Japanese-Patent No. 2012-22217

  However, even when using the RGBW pixel panel, power consumption increases as in the case of the conventional panel when performing high brightness display, and heat is a problem particularly in a small housing. Therefore, for HDR display, it can not be used at 1000 nits or more, or the display can be limited at 1000 nits or more, and the display capability is limited.

  Therefore, an object of the present invention is to provide an image processing apparatus capable of reducing power consumption by changing the light emission intensity of the white sub-pixel according to the temperature of the display means in the HDR assist mode. It is.

In order to achieve the above object, an image processing apparatus according to the present invention comprises an imaging means, a display means in which color pixels including red, green, blue and white sub-pixels are arranged, and an emission brightness of the display means. Controllable light emission luminance control means, and intensity control means capable of changing the light emission intensity of the white sub-pixel;
A temperature detection unit that detects the temperature of the display unit; and an HDR assist mode detection unit that detects whether the display unit has an HDR assist mode that displays an image having a wide dynamic range, the HDR assist mode When the temperature detected by the temperature detection means is higher than the threshold, the intensity set in the intensity control means is taken as a first set value, and the temperature detected by the temperature detection means is the threshold If lower, the set value set in the intensity control means is a second set value having a smaller intensity than the intensity set by the first set value.

  According to the present invention, when in the HDR assist mode, power consumption can be reduced by changing the emission intensity of the white sub-pixel according to the temperature of the display means.

A diagram showing a configuration example of an imaging device according to an embodiment of the present invention The figure which shows the example of a sub-pixel arrangement | positioning of the liquid crystal panel concerning embodiment of this invention. The figure which shows the relationship between W intensity | strength and BL intensity | strength which concerns on embodiment of this invention. The figure which shows the relationship between W intensity | strength, BL electric current, and image quality concerning embodiment of this invention. The figure which shows the relationship of the temperature of the liquid crystal display part which concerns on embodiment of this invention, and time. The figure which shows the relationship of the temperature of the liquid crystal display part which concerns on embodiment of this invention, and time. A diagram showing an example of a processing flow according to an embodiment of the present invention

First Embodiment
Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 1 to 7. Although an example in which the image processing apparatus according to the present embodiment is provided in a photographing apparatus (digital camera) will be described below, the image processing apparatus according to the present embodiment is an apparatus separate from the photographing apparatus ( It may be a personal computer, a display device, etc.).

  Furthermore, although an example in which the imaging device has a display unit (display means) will be described below, the display unit may be a display device separate from the imaging device. The display unit may be a display device separate from the image processing apparatus according to the present embodiment, or may be a display unit provided in the image processing apparatus according to the present embodiment.

  Furthermore, although an example in which the display unit is a liquid crystal display unit having a backlight module and a liquid crystal panel will be described below, the display unit is not limited to the liquid crystal display unit. For example, another display unit having a light emitting unit and a display panel that displays an image by transmitting light from the light emitting unit may be used.

  Specifically, a MEMS shutter type display unit using a MEMS (Micro Electro Mechanical System) shutter as a display element may be used. A self-luminous display may be used. Specifically, an organic EL (Electro-Luminescence) display panel, a plasma display panel, or the like may be used.

  The configuration of the photographing apparatus (digital video camera) according to the present embodiment will be described with reference to FIG. FIG. 1 shows a configuration example of an imaging device according to the present embodiment. The control unit 101 performs various processes of the imaging device. The control unit 101 includes a signal processing unit 103, a recording / reproducing unit 104, a liquid crystal display unit 105, a backlight driving unit 109, a power control unit 112, an operation unit 113, a memory 114, an HDR assist mode detection unit 115, and a temperature. The detection unit 116 is connected.

  The control unit 101 includes a data processing unit 110 and a display processing unit 111. The liquid crystal display unit 105 includes a touch panel 106, a liquid crystal panel 107, a backlight unit 108, an RGBW control unit 117, and a backlight control unit 118. . The backlight control unit 118 is connected to the backlight drive unit 109.

  The image / voice input unit 102 acquires an image signal which is an analog signal representing an image and an audio signal which is an analog signal representing an audio, and outputs the image signal and the audio signal to the signal processing unit 103. In the present embodiment, the image / voice input unit 102 includes an imaging unit (image sensor; imaging element) and a voice input unit (microphone). Light from the subject enters the imaging unit through the lens. Thereby, an optical image representing a subject is formed (formed) in the imaging unit.

  The imaging unit converts the formed optical image into an image signal having a predetermined signal format, and outputs the image signal. The audio input unit converts the input audio into an audio signal and outputs an audio signal.

  The signal processing unit 103 performs predetermined image processing on the analog signal output from the image / voice input unit 102. The predetermined image processing includes processing on an image signal, processing on an audio signal, or both of them. The predetermined signal processing includes, for example, noise reduction processing for reducing noise components, AGC (Automatic Gain Control) processing for keeping the signal level constant, and the like. The signal processing unit 103 includes an A / D conversion unit that converts an analog signal after predetermined signal processing into a digital signal (digital data).

  The signal processing unit 103 outputs the digital data (image data that is digital data representing an image and audio data that is digital data representing audio) obtained by the A / D converter to the control unit 101.

  The recording / reproducing unit 104 performs recording processing, reproduction processing, and the like. The recording process is a process of recording digital data (image data and audio data) output from the control unit 101 to the recording / reproducing unit 104 in a storage unit. The reproduction process is a process of reading digital data (image data and sound data) from the storage unit and outputting the read digital data to the control unit 101. In the present embodiment, the recording process and the reproduction process are switched and executed in accordance with an instruction from the control unit 101.

  The touch panel 106 is an operation unit that can receive various operations on the imaging apparatus. For example, the touch panel 106 performs mode setting operation instructing setting of a display mode, mode releasing operation instructing releasing a setting of the display mode, recording operation instructing execution of a recording process, and reproduction operation instructing execution of a reproduction process. Etc. can be accepted. Specifically, the touch panel 106 detects the touch of the user on the touch panel 106, and outputs the detection result of the touch (touch position, touch time, change in touch position, etc.) to the control unit 101.

  The control unit 101 determines the performed operation from the contact detection result. In the present embodiment, the touch panel 106 is provided on the display surface (screen) of the liquid crystal panel 107. The touch panel 106 may be provided at another position. When the user performs a mode setting operation on the imaging apparatus, the control unit 101 sets a display mode corresponding to the mode setting operation. The control unit 101 can set one or more display modes among a plurality of display modes. When the user performs a mode release operation on the imaging apparatus, the control unit 101 cancels the setting of the display mode corresponding to the mode release operation.

  The liquid crystal panel 107 is a display means capable of displaying a reproduced video and an imaged video, and becomes a liquid crystal panel of a backlight type provided with a backlight unit 108 at the rear of the liquid crystal panel 107. FIG. 2 is a view showing an arrangement example of sub-pixels of the liquid crystal panel 107 according to the present embodiment. As shown in FIGS. 2A and 2B, in the liquid crystal panel 107, each pixel is configured by four sub-pixels of R (red), G (green), B (blue), and W (white). The shape and arrangement of the R, G, B, and W sub-pixels in each pixel are not particularly limited.

  Under the control of the control unit 101, the liquid crystal display unit 105 controls the liquid crystal panel 107 to display the video signal input from the display processing unit 111. The control unit 101 controls ON / OFF of image display on the liquid crystal panel 107. Further, a control signal is input from the control unit 101 to the backlight driving unit 109, and the backlight unit 108 is lit. The liquid crystal display unit 105 includes an RGBW control unit 117 and a backlight control unit 118.

  The RGBW control unit 117 uses the W intensity setting value for controlling the transmission amount (hereinafter, W intensity) MAX value of the W pixel from the control unit 101 and the image analysis of the input RGB signal. Hereinafter, the calculation of the BL value) and the generation of the RGBW signal in each pixel of the liquid crystal panel 107 are performed. The BL value obtained by the RGBW control unit 117 is output to the backlight control unit 118.

  The backlight control unit 118 adjusts the brightness of the backlight unit 108 in accordance with a backlight level setting value (hereinafter referred to as a BL level setting value) for arbitrarily changing the BL value and the backlight brightness from the control unit 101. The backlight control unit 109 outputs a backlight control signal (hereinafter, referred to as a BL control signal) for the purpose. The BL control signal is a product of the BL value and the BL level setting value.

  FIG. 3 is a diagram showing the relationship between the W intensity and the backlight intensity. In FIG. 3, hatched portions indicate possible regions of the BL value with respect to the W intensity. As the W intensity is larger, the possible range of the BL value is wider, that is, the minimum value of the BL value is lower, and the reduction ratio of the power consumption is larger. Conversely, when the W intensity is small, the possible range of the BL value narrows, that is, the minimum value of the BL value increases, and the reduction rate of the power consumption decreases.

  The backlight unit 108 uses a white light source such as a cold cathode fluorescent lamp (CCFL) or a white light emitting diode (white LED), and the backlight driving unit 109 controls the brightness in proportion to the BL control signal. be able to. The method of controlling the brightness of the backlight unit 108 varies depending on the type of light source used, but, for example, the brightness is controlled by applying a voltage proportional to the backlight value or supplying a current proportional to the backlight value can do.

  When the backlight is an LED or the like, it is also possible to control the brightness by changing the duty ratio by pulse width modulation (PWM). Furthermore, when the brightness of the backlight source has non-linear characteristics, a desired brightness can be obtained by performing brightness control on the backlight by obtaining an applied voltage or applied current to the light source from the backlight value using a lookup table. There is also a way to control the

  The input signal is not limited to the above-mentioned RGB signal, but may be a color signal such as a YUV signal. When a color signal other than the RGB signal is input, the color signal may be converted to the RGB signal and then input to the RGBW control unit 117. Alternatively, the RGBW control unit 117 may be configured to input the color input signal other than the RGB signal. It may be a configuration that can be converted to an RGBW signal.

  The data processing unit 110 acquires input image data and input audio data. For example, while the reproduction process is being performed, the data processing unit 110 acquires the image data output from the recording and reproduction unit 104 as input image data, and inputs the audio data output from the recording and reproduction unit 104 Acquire as voice data. During a period in which the reproduction process is not performed, the data processing unit 110 acquires image data output from the signal processing unit 103 as input image data, and acquires audio data output from the signal processing unit 103 as input audio data. Do. In the present embodiment, when the user performs a reproduction operation on the imaging apparatus, the control unit 101 instructs the recording and reproduction unit 104 to execute the reproduction process. As a result, the recording / reproducing unit 104 performs reproduction processing.

  The data processing unit 110 performs predetermined data processing on the acquired digital data. The predetermined data processing includes processing on input image data, processing on input audio data, or both of them. The predetermined data processing includes, for example, format conversion processing for converting the data format of digital data, resize processing for converting the image size of input image data, and synthesis processing for combining graphic image data with input image data.

  The graphic image data is, for example, OSD (On Screen Display) image data representing a menu image or the like. The data processing unit 110 outputs the image data after the predetermined data processing to the display processing unit 111, and outputs the audio data after the predetermined data processing to the speaker. The speaker emits an audio according to the audio data output to the speaker.

  Further, the data processing unit 110 can output the digital data (image data and audio data) output from the signal processing unit 103 to the recording / reproducing unit 104. In the present embodiment, when the user performs a recording operation on the imaging apparatus, the control unit 101 instructs the recording / reproducing unit 104 to execute the recording process. Then, the data processing unit 110 outputs the digital data output from the signal processing unit 103 to the recording / reproducing unit 104. As a result, the recording / reproducing unit 104 performs the recording process.

  In the present embodiment, photographed image data (image data representing an image of a subject) is used as input image data. However, input image data is not limited to photographed image data. For example, the input image data may be computer graphic image data, illustration image data, or the like. The input image data may be still image data or moving image data.

  The display processing unit 111 performs processing based on the set display mode. Then, the display processing unit 111 outputs the image data after the above processing (processing based on the set display mode) to the liquid crystal panel 107. The image data output to the liquid crystal panel 107 is image data based on the input image data output from the data processing unit 110. Therefore, the liquid crystal display unit 105 displays an image based on the input image data.

  The power supply operation unit 112 is an operation unit (such as a switch) capable of receiving a start operation instructing the start of the imaging apparatus and a stop operation instructing the stop of the imaging apparatus. It can be said that the start operation is an operation to instruct switching from the off state to the on state (switching of the power supply state of the photographing apparatus), and the stop operation is an operation to instruct the switching of the power state from the on state to the off state. It can be said that. When the user performs an activation operation on the imaging apparatus, the control unit 101 performs an activation process for activating the imaging apparatus. When the user performs a stop operation on the imaging apparatus, the control unit 101 performs stop processing for stopping the imaging apparatus.

  The operation unit 113 is an operation unit (such as a switch) that can receive various operations on the imaging apparatus. For example, the operation unit 113 can receive a mode setting operation, a mode release operation, a recording operation, a reproduction operation, and the like. The operations that can be received by the operation unit 113 may be the same as or different from the operations that can be received by the touch panel 106.

  The memory 114 temporarily stores data and the like used in the processing of the control unit 101.

  The HDR assist mode detection unit 115 detects the setting of the HDR assist mode. The HDR assist mode is a mode for displaying on the liquid crystal display unit 105 so that the user can confirm the tonality of the HDR image data, and the luminance of the backlight unit 108 is the highest.

  Then, the HDR assist mode detection unit 115 outputs the detection result of the setting of the HDR assist mode to the display processing unit 111. In other words, the HDR assist mode detection unit 115 determines whether the HDR assist mode is set. Then, the HDR assist mode detection unit 115 outputs the determination result as to whether or not the HDR assist mode is set to the display processing unit 111.

  The temperature detection unit 116 detects the temperature of the liquid crystal display unit 105.

The relationship between the W intensity, the BL current, and the image quality deterioration of the RGBW pixel panel according to the present embodiment will be described with reference to FIG. Modes 1 and 2 are settings for setting the luminance to 1000 cd / m ² and are used when performing high-intensity display at the time of HDR assist. Mode 1 is a mode in which the W intensity is reduced (setting value: W1) and image quality deterioration is eliminated. That is, since the amount of W used is reduced, it is necessary to increase the BL current in order to achieve high luminance, and power consumption is large. In this embodiment, 22 mA (set value: B1) is set.

  In mode 3, image quality deterioration appears notably by increasing the W intensity (setting value: W3), but since the amount of W used is increased, the BL current can be reduced and power consumption is small. In this embodiment, 12 mA (set value: B3) is used. Mode 2 is a mode in which the W intensity is set to a medium level (setting value: W2) and power consumption is reduced more than in mode 1 although there is a slight deterioration in image quality.

In the present embodiment, the BL current is 17 mA (set value: B2). Mode 4 is used in the normal shooting mode other than the HDR assist. The luminance is set to 200 cd / m ² because high luminance display is not necessary. In this mode, the W intensity is reduced (set value: W4), the image quality is not deteriorated, and the luminance is also reduced. In the present embodiment, the BL current is 5 mA (set value: B4).

  It is a figure showing the relationship of time and the temperature of the liquid crystal display part 105 at the time of displaying in mode 1-3 in FIG. In the order of mode 1, mode 2 and mode 3, saturation occurs at high temperature. That is, as the BL current increases, saturation occurs at a higher temperature.

  An example of the process flow of the imaging device according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing an example of the processing flow of the imaging device according to the present embodiment. The processing flow of FIG. 7 is executed, for example, according to the start-up operation using the power supply operation unit 112, the recording operation using the operation unit 113, or the like.

  In S701, the HDR assist mode detection unit 115 determines whether the HDR assist mode is set. If the HDR assist mode is set, the process proceeds to step S702. If the HDR assist mode is not set, the process proceeds to step S707. In S707, the setting of mode 4 in FIG. 4 is applied, and the process proceeds to S708.

  In S702, the temperature detection unit 116 determines whether the temperature threshold α1 or more. If it is the temperature threshold α1 or more, the process proceeds to S704. If it is less than the temperature threshold α1, the process proceeds to S703. In S703, the setting of mode 1 in FIG. 4 is applied, and the process proceeds to S708.

  FIG. 6 is a diagram showing a temperature change when shifting to the HDR assist mode. Since S703 is less than the temperature threshold value α1 when switched to the HDR assist mode, it is in the state shown in the left end of FIG. 6 and exceeds the limit temperature in the liquid crystal display unit 105 in all modes 1 to 3. There is no. Therefore, the image is displayed in mode 1 without image quality deterioration. Here, the limit temperature means the guaranteed temperature upper limit of the parts forming the liquid crystal display unit.

  In S704, the temperature detection unit 116 determines whether the temperature threshold α2 or more. The temperature threshold α2 is a temperature higher than the temperature threshold α1. If the temperature threshold α2 or more, the process proceeds to S706, and if less than the temperature threshold α2, the process proceeds to S705. In S705, the setting of mode 2 in FIG. 4 is applied, and the process proceeds to S708.

  S705 is the temperature threshold α1 or more and less than α2 when the mode is switched to the HDR assist mode, which is the state shown in the middle of FIG. 6, and the mode 1 exceeds the limit temperature in the unit. Therefore, mode 1 can not be set. Modes 2 to 3 can be set because they do not exceed the limit temperature, and are displayed in mode 2 with less image quality deterioration.

  In S706, the setting of mode 3 in FIG. 4 is applied, and the process proceeds to S708. Since S706 is the temperature threshold value α2 or more when switched to the HDR assist mode, it is in the state of the right end of FIG. 6, and modes 1 and 2 exceed the limit temperature in the unit. Therefore, the mode 1 and 2 can not be set. Mode 2 can be set because the temperature does not exceed the limit temperature, and is displayed in mode 3 in which the image quality deterioration is large but the power consumption is small and the temperature rise is small. As described above, in the HDR assist mode, it is a mode for checking the tonality of the subject, and it is desirable that the luminance be high even if some image quality deterioration is allowed.

  At S 708, control unit 101 determines whether a stop operation using power supply operation unit 112 has been performed. If the stop operation has not been performed, the process returns to S701. Then, the processes of S701 to S708 are repeated until the stop operation is performed. When the stop operation is performed, the present processing flow is ended. Note that the method of determining whether to end the process flow of FIG. 7 is not limited to this. For example, the processing of S701 to S708 may be repeated until a reproduction end operation (an operation to instruct the end of the reproduction processing) is performed, and the processing flow of FIG. 7 may be ended according to the reproduction end operation. The processing of S701 to S708 may be repeated until the recording end operation (an operation for instructing the end of the recording processing) is performed, and the processing flow of FIG. 7 may be ended according to the recording end operation.

  As described above, according to the present embodiment, the HDR assist mode is set, and the power consumption is reduced while maintaining the display brightness by changing the W intensity according to the temperature of the liquid crystal display unit, The temperature rise of the liquid crystal display unit can be suppressed.

  The values of the luminance and the BL current in the present embodiment are not limited to these values, and the optimum value changes depending on the specifications of the liquid crystal display unit, and can be changed as appropriate. Further, the method of dividing the RGBW pixel panel mode in this embodiment is not limited to this, and the types of modes may be reduced or increased, and can be appropriately changed.

  Although the present invention has been described in detail based on its preferred embodiments, the present invention is not limited to these specific embodiments, and various embodiments within the scope of the present invention are also included in the present invention. included. Some of the embodiments described above may be combined as appropriate.

101: Control unit 102: Image and voice input unit 103: Signal processing unit 104: Recording and reproduction unit 105: Liquid crystal display unit 106: Touch panel 107: Liquid crystal panel 108: Back light unit 109: Backlight drive unit 110 .. Data processing unit 111 .. Display processing unit 112 .. Power supply operation unit 113 .. Operation unit 114 .. Memory 115 .. HDR assist mode detection unit 116 .. Temperature detection unit 117 .. RGBW control Unit 118 ..... Backlight control unit

Claims (1)

Imaging means,
Display means in which color pixels including red, green, blue and white sub-pixels are arranged;
Light emission luminance control means capable of controlling the light emission luminance of the display means;
Intensity control means capable of changing the emission intensity of the white sub-pixel;
Temperature detection means for detecting the temperature of the display means;
HDR assist mode detection means for detecting whether or not an HDR assist mode for displaying an image with a wide dynamic range on the display means is detected;
Equipped with
In the HDR assist mode, when the temperature detected by the temperature detection unit is higher than a threshold, the intensity set in the intensity control unit is set as a first set value.
When the temperature detected by the temperature detection means is lower than the threshold value, the setting value set in the intensity control means is a second setting value having a smaller intensity than the intensity set in the first setting value. An image processing apparatus characterized in that.