JP6628826B2 - Display device and display method - Google Patents

Description

  The present invention relates to a display device and a display method.

  In recent years, an imaging device capable of generating captured image data having a wide dynamic range has been increasing. The wide dynamic range is called “High Dynamic Range (HDR)” and the like, and image data having HDR is called “HDR image data” and the like. In the field of image production, development of devices (image processing devices, display devices, etc.), the chances of assuming HDR image data are increasing.

In order to realize a display image faithful to the HDR image data, a high-precision display device is required. For example, a display device that can realize a display image having a high upper limit of display luminance and high contrast and realizing a display image with a wide dynamic range is required. Hereinafter, a display device capable of realizing a display image faithful to the HDR image data will be referred to as an “HDR display device”. For example, a display device that satisfies the condition that the upper limit of the display luminance is 1000 nits (= 1000 cd / m ² ) and the lower limit of the display luminance is 0.03 nits or less is defined as an HDR display device. A liquid crystal display device that satisfies the condition that the upper limit of the display luminance is 1000 nits or more and the lower limit of the display luminance is 0.05 nits or less may be defined as the HDR display device. A self-luminous display device (such as an organic EL display device) satisfying the condition that the upper limit of the display luminance is 540 nits or more and the lower limit of the display luminance is 0.0005 nits or less may be defined as the HDR display device. .

  However, HDR display devices cannot always be used at various sites. For example, at a shooting site, a non-HDR display device is used due to restrictions on power supplies, restrictions on belongings, and the like. The non-HDR display device is an SDR (Standard Dynamic Range) display device that is not an HDR display device, an HDR display device with a limited display capability, and the like. The non-HDR display device is, for example, a display device in which the dynamic range of the display luminance is narrow and the upper limit of the display luminance is low.

  The non-HDR display device cannot realize a display image faithful to the HDR image data. In the non-HDR display device, a display in which the dynamic range of the HDR image data is compressed is performed as the display of the HDR image data. That is, in the non-HDR display device, the display in which at least a part of the gradation of the HDR image data (gradation in the high luminance range, gradation in the low luminance range, etc.) is reduced as the display of the HDR image data. Done.

  Techniques related to changing the gradation of a display image are disclosed in, for example, Patent Documents 1 and 2. According to the technique disclosed in Patent Document 1, a brightness distribution diagram showing a brightness distribution of image data to be displayed is displayed, and a user can easily change the gradation of the image data using the brightness distribution diagram. it can. In the technique disclosed in Patent Document 2, the average luminance of image data is detected, and when the average luminance is low, the emission luminance of the backlight unit is reduced, and when the average luminance is high, the emission luminance of the backlight unit is increased.

JP 2007-228048 A JP 2008-58443 A

  However, in the related art, when attention is paid to a part of the gradation range of the image data, the part may not be visually recognized at a suitable display luminance.

  Therefore, an object of the present invention is to provide a technique capable of visually recognizing a part of the gradation range of image data with a suitable display luminance when the part is focused on.

A first aspect of the present invention provides:
Display means for displaying an image based on display image data generated from the input image data;
Control means for controlling the emission luminance of the light source of the display means,
Detecting means for detecting a user operation for specifying a position in the image;
With
The control means,
When the gradation value of the input image data corresponding to the position specified by the user operation is equal to or greater than a first threshold, the light emission luminance of the light source of the display unit is set to a light emission luminance lower than the set light emission luminance. A first control to control ;
When the tone value of the input image data corresponding to the position specified by the user operation is less than a second threshold, the light emission luminance of the light source is controlled to a light emission luminance higher than a set light emission luminance . Two controls,
Do at least one of
The second threshold is less than the first threshold,
The control unit sets the light emission luminance of the light source when a gradation value of the input image data corresponding to the position designated by the user operation is equal to or greater than the second threshold and less than the first threshold. The display device is characterized in that the light emission luminance is controlled .

A second aspect of the present invention provides:
A display step of displaying on the display means an image based on the display image data generated from the input image data,
A control step of controlling the light emission luminance of the light source of the display means,
A detecting step of detecting a user operation for designating a position in the image;
Has,
In the control step,
When the gradation value of the input image data corresponding to the position specified by the user operation is equal to or greater than a first threshold, the light emission luminance of the light source of the display unit is set to a light emission luminance lower than the set light emission luminance. A first control to control ;
The control when the gradation value of the input image data corresponding to the position specified by the user operation is less than the second threshold value, the light emission luminance of the light source, the high luminance than the light emission luminance which is set Two controls,
Do at least one of
The second threshold is less than the first threshold,
In the control step, when the gradation value of the input image data corresponding to the position designated by the user operation is equal to or more than the second threshold and less than the first threshold, the light emission luminance of the light source is set. The display method is characterized in that the light emission brightness is controlled .

  A third aspect of the present invention is a program for causing a computer to execute each step of the above-described display method.

  According to the present invention, when attention is paid to a part of the gradation range of the image data, the part can be visually recognized at a suitable display luminance.

1 is a block diagram illustrating a configuration example of an imaging device according to a first embodiment. FIG. 2 is a block diagram illustrating a configuration example of a display processing unit according to the first embodiment. FIG. 5 is a diagram illustrating an example of an image according to the first embodiment. FIG. 7 is a diagram illustrating an example of a conversion characteristic according to the first embodiment. 5 is a flowchart illustrating an example of a processing flow according to the first embodiment. FIG. 5 is a diagram illustrating an example of an image according to the first embodiment. FIG. 10 is a diagram illustrating an example of a gradation characteristic and a conversion characteristic according to the second embodiment. FIG. 10 is a diagram illustrating an example of a gradation characteristic and a conversion characteristic according to the second embodiment. FIG. 9 is a block diagram illustrating a configuration example of an imaging device according to a third embodiment. 11 is a flowchart illustrating an example of a processing flow according to the third embodiment. Another diagram showing an example of the gradation characteristic and the conversion characteristic according to the second embodiment.

<Example 1>
Hereinafter, Embodiment 1 of the present invention will be described. The display device according to the present embodiment is a device capable of displaying an image, and is not particularly limited. For example, a display device is a transmissive display device including a light-emitting unit and a display panel that displays an image by transmitting light emitted from the light-emitting unit. The transmissive display device is a liquid crystal display device, a MEMS (Micro Electro Mechanical System) shutter type display device, or the like. The display device may be a self-luminous display device such as an organic EL (Electro-Luminescence) display device or a plasma display device. Display devices include a projection device (projector), a personal computer, a PDA, a tablet terminal, a mobile phone terminal (including a smartphone), a television device, an imaging device (digital camera), a digital photo frame, a game machine, a home appliance, and a vehicle-mounted device. , Etc.

  A configuration example of an imaging device (digital video camera) that is a liquid crystal display device according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration example of the imaging apparatus according to the present embodiment.

  The control unit 101 performs various processes of the imaging device. The control unit 101 is connected to a signal processing unit 103, a recording / reproducing unit 104, a liquid crystal display unit 105, a backlight driving unit 109, a power operation unit 112, an operation unit 113, and a memory 114. The control unit 101 includes a data processing unit 110 and a display processing unit 111, and the liquid crystal display unit 105 includes a touch panel 106, a liquid crystal panel 107, and a backlight unit 108.

  The image / audio input unit 102 acquires an image signal that is an analog signal representing an image and an audio signal that is an analog signal representing audio, and outputs the image signal and the audio signal to the signal processing unit 103. The image / sound input unit 102 includes an image pickup unit (image pickup sensor; image pickup device) and a sound input unit (microphone). Light from the subject enters the imaging unit via the lens. Thereby, an optical image representing the subject is formed (imaged) on the imaging unit. The imaging unit converts the formed optical image into an image signal having a predetermined signal format, and outputs an image signal. The audio input unit converts the input audio to an audio signal and outputs the audio signal.

The signal processing unit 103 performs predetermined signal processing on the analog signal output from the image / audio input unit 102. The predetermined signal processing includes signal processing for image signals, signal processing for audio signals, or both. The predetermined signal processing includes, for example, noise reduction processing for reducing noise components, and AGC (Automatic Gain) for maintaining a constant signal level.
Control) processing. 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 digital data (image data, which is digital data representing an image, and audio data, which is digital data representing audio) obtained by the A / D conversion unit to the control unit 101.

  The recording / playback unit 104 performs a recording process, a playback process, 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 / playback unit 104 in the storage unit. The reproduction process is a process of reading digital data (image data and audio data) from the storage unit and outputting the read digital data to the control unit 101. The recording process and the reproduction process are switched and executed according to an instruction from the control unit 101.

The touch panel 106 is an operation unit that can receive various user operations (operations performed by the user) on the imaging device. For example, the touch panel 106 includes a mode setting operation for instructing the setting of the display mode, a mode release operation for instructing the release of the display mode setting, a recording operation for instructing the execution of the recording process, a reproducing operation for instructing the execution of the reproducing process, Etc. can be accepted. Specifically, the touch panel 106 detects a user's contact with the touch panel 106, and outputs a result of the contact detection (a contact position, a contact time, a change in the contact position, and the like) to the control unit 101. The control unit 101 determines the user operation that has been performed based on the detection result of the contact. When the mode setting operation is performed, 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 mode release operation is performed, the control unit 101 releases the setting of the display mode corresponding to the mode release operation. Although the arrangement of the touch panel 106 is not particularly limited, in this embodiment, the touch panel 106 is provided on the display surface (screen) of the liquid crystal panel 107.

  An image based on the processed image data is displayed on the screen by the liquid crystal panel 107 and the backlight unit 108. The backlight unit 108 irradiates the back surface of the liquid crystal panel 107 with light. The liquid crystal panel 107 displays an image based on the processed image data by transmitting the light emitted from the backlight unit 108 based on the processed image data. Specifically, when the display image data is output from the control unit 101 to the liquid crystal panel 107, a liquid crystal drive signal (current) corresponding to the gradation value of the display image data is supplied to each of the plurality of liquid crystal elements included in the liquid crystal panel 107. , Voltage, etc.). As a result, the transmittance (transmittance distribution) of the liquid crystal panel 107 is controlled to a transmittance according to the display image data. Therefore, the liquid crystal panel 107 displays an image based on the display image data by transmitting the light emitted from the backlight unit 108 according to the display image data. The display image data is processed image data or image data obtained by performing data processing (image processing) on the processed image data. Therefore, the transmittance according to the display image data is also a transmittance based on the processed image data, and the image based on the display image data is also an image based on the processed image data.

  The backlight drive unit 109 supplies a backlight drive signal (current, voltage, etc.) to the backlight unit 108. For example, the backlight drive unit 109 is a power supply circuit that supplies current to the backlight unit 108. The backlight unit 108 emits light at a light emission luminance (light emission amount) according to the supplied backlight drive signal. The control unit 101 can control the light emission luminance of the backlight unit 108. Specifically, the control unit 101 can control a backlight drive signal output from the backlight drive unit 109. By controlling the backlight drive signal, the light emission luminance of the backlight unit 108 is controlled. The display luminance (screen luminance) is controlled by controlling the light emission luminance of the backlight unit 108.

  The data processing unit 110 acquires input image data and input audio data. For example, during a period in which the reproduction process is being performed, the data processing unit 110 acquires the image data output from the recording / reproduction unit 104 as input image data, and inputs the audio data output from the recording / reproduction unit 104. Get as audio data. During a period in which the reproduction process is not performed, the data processing unit 110 acquires the image data output from the signal processing unit 103 as input image data, and acquires the audio data output from the signal processing unit 103 as input audio data. I do. In this embodiment, when a reproduction operation is performed, the control unit 101 instructs the recording / reproduction unit 104 to execute a reproduction process. As a result, the recording / reproducing section 104 performs a reproducing process.

The data processing unit 110 performs predetermined data processing on the acquired digital data. The predetermined data processing includes data processing for input image data, data processing for input audio data, or both. The predetermined data processing includes, for example, format conversion processing for converting the data format of digital data, resizing processing for converting the image size of input image data, synthesis processing for synthesizing graphic image data with input image data, and the like. The graphic image data is, for example, an OSD (On Screen) representing a menu image or the like.
n Display) image data. 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 sound according to the sound 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 this embodiment, when a recording operation is performed, the control unit 101 instructs the recording / reproduction unit 104 to execute a 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 a recording process.

  In the present embodiment, captured image data (image data representing a subject) is used as input image data. However, input image data is not limited to captured 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 data processing on the image data output from the data processing unit 110 based on the set display mode. Thereby, display image data is generated. Then, the display processing unit 111 outputs the display image data to the liquid crystal panel 107. As described above, in the present embodiment, the control unit 101 (the data processing unit 110 and the display processing unit 111) converts the input image data into the display image data.

  The power operation unit 112 is an operation unit (such as a switch) that can receive a start operation for instructing activation of the imaging device and a stop operation for instructing stop of the imaging device. The start operation can be said to be an "operation for instructing switching from the off state to the on state (switching the power state of the imaging device)", and the stop operation is an "operation for instructing switching of the power state from the on state to the off state". It can also be said. When the user performs a start operation on the imaging device, the control unit 101 performs a start process for starting the imaging device. When the user performs a stop operation on the imaging device, the control unit 101 performs a stop process for stopping the imaging device.

  The operation unit 113 is an operation unit (such as a switch) that can receive various user operations on the imaging device. 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 operation that the operation unit 113 can accept may be the same as or different from the user operation that the touch panel 106 can accept.

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

  A configuration example of the display processing unit 111 will be described with reference to FIG. FIG. 2 is a block diagram illustrating a configuration example of the display processing unit 111. In this embodiment, YCbCr data is output from the data processing unit 110 to the display processing unit 111. The YCbCr data is image data in which each pixel value is a YCbCr value (a combination of a Y value, a Cr value, and a Cb value).

  The gain / sharpness correction unit 201 generates processed luminance data by performing predetermined data processing on luminance data (Y value of each pixel) included in the YCbCr data. The predetermined data processing includes, for example, a gain adjustment processing for adjusting a gradation value (Y value), a sharpness correction processing for emphasizing an edge, and the like. Then, the Gain / sharpness correction unit 201 outputs the processed luminance data to the RGB conversion unit 203.

  The Gain / color correction unit 202 generates processed color difference data by performing predetermined data processing on the color difference data (Cb value and Cr value of each pixel) included in the YCbCr data. The predetermined data processing includes, for example, a gain adjustment processing for adjusting a gradation value (at least one of a Cb value and a Cr value), a color correction processing for adjusting a color (saturation, hue, and the like), and the like. Then, the Gain / color correction unit 202 outputs the processed color difference data to the RGB conversion unit 203.

  The RGB conversion unit 203 generates a combination of the processed luminance data and the processed color difference data (each pixel value is a combination of the Y value of the processed luminance data, the Cb value of the processed color difference data, and the Cr value of the processed color difference data, YCbCr data). Is converted to RGB data. The RGB data is image data in which each pixel value is an RGB value (a combination of an R value, a G value, and a B value). For example, the RGB conversion unit 203 converts YCbCr data into RGB data by one-dimensional matrix operation processing. Then, the RGB conversion unit 203 outputs the RGB data to the gradation conversion unit 204.

  The gradation conversion unit 204 generates processed image data by performing gradation conversion processing on the RGB data output from the RGB conversion unit 203. The gradation conversion processing is data processing for converting the correspondence between the gradation value of the image data to be processed and the display luminance, and is, for example, gamma correction processing. The method of the gradation conversion processing is not particularly limited. For example, in the gradation conversion processing, the gradation value of the image data is converted using information (lookup table, function, etc.) indicating the correspondence between the gradation value before conversion and the gradation value after conversion. You. The gradation conversion unit 204 performs a gradation conversion process for each of the R value, the G value, and the B value. Thereby, RGB data is generated as processed image data. The gradation conversion unit 204 outputs the processed image data to the brightness / contrast correction unit 205.

  The brightness / contrast correction unit 205 generates display image data by performing a brightness correction process, a contrast correction process, and the like on the processed image data output from the gradation conversion unit 204. The brightness correction process is a data process for correcting the brightness of the image data, and the contrast correction process is a data process for correcting the contrast of the image data. The display brightness is controlled by controlling the brightness correction processing, and the display contrast (screen contrast) is controlled by controlling the contrast correction processing. The brightness / contrast correction unit 205 performs a brightness correction process, a contrast correction process, and the like for each of the R value, the G value, and the B value. Thereby, RGB data is generated as display image data. The luminance / contrast correction unit 205 outputs display image data to the liquid crystal panel 107. In order to generate display image data from the processed image data, other data may be processed on the processed image data.

  For the sake of simplicity, in this embodiment, it is assumed that the input image data is also RGB data. It is assumed that the gradation value of the input image data, the gradation value of the processed image data, the gradation value of the display image data, and the like are 8-bit values (256 levels). As the gradation value of the processed image data, the gradation value of the display image data, etc. increase, the display brightness, the transmittance of the liquid crystal element, the value of the liquid crystal drive signal (current value, voltage value, etc.) are linear. To increase. It is assumed that the display image data is equal to the processed image data. The number of bits of the gradation value of each image data, the data format of each image data, and the like are not particularly limited. Correspondence between the gradation value of the processed image data, the gradation value of the display image data, the display luminance, the transmittance of the liquid crystal element, the value of the liquid crystal drive signal, and the like is not particularly limited. For example, display luminance, transmittance of a liquid crystal element, value of a liquid crystal drive signal (current value, voltage value, etc.), etc., for an increase in the gradation value of processed image data, the gradation value of display image data, etc. May increase non-linearly.

An example of a method for setting the dynamic range assist mode will be described. The dynamic range assist mode is a display mode for performing a display (assist display) in which the gradation of a target range which is a part of the gradation range (gradation value range; dynamic range) of the input image data is enhanced.

  First, an activation operation using the power supply operation unit 112 is performed, and power is supplied to each functional unit of the imaging apparatus. Next, a mode setting operation for instructing the setting of the camera recording mode is performed using the operation unit 113, and the control unit 101 sets the camera recording mode.

  At this time, gradation conversion processing for converting the input level to the output level is performed with a predetermined conversion characteristic (correspondence relationship between the input level and the output level), and the image of FIG. Is displayed. The input level is a gradation value before conversion, and corresponds to the gradation value of the input image data. The output level is a gradation value after conversion, and corresponds to a gradation value of processed image data, a gradation value of display image data, and the like. The image in FIG. 3A is an image based on the input image data (captured image data) output from the signal processing unit 103, and is a captured image representing the current state of the subject.

  Although the predetermined conversion characteristic is not particularly limited, in the present embodiment, the predetermined conversion characteristic is a conversion characteristic corresponding to a standard gamma value of 2.2, and is the conversion characteristic GLUT1 in FIG. The horizontal axis of FIG. 4A indicates the input level, and the vertical axis of FIG. 4A indicates the output level. The image in FIG. 3A is an image after the gradation conversion processing using the conversion characteristic GLUT1 in FIG. 4A. The output level can be said to be "display luminance". The conversion characteristic GLUT1 may be a reverse characteristic of the gradation characteristic of the input image data (captured image data).

  Then, a mode setting operation for instructing the setting of the dynamic range assist mode is performed using the touch panel 106, and the control unit 101 sets the dynamic range assist mode. For example, a menu image is displayed in response to a user operation on the operation unit 113, the touch panel 106, and the like. As a mode setting operation for instructing the setting of the dynamic range assist mode, a user operation of touching a predetermined portion of the displayed menu image is performed. Done. Thereby, the image displayed on the screen transits from the image of FIG. 3A to the images of FIGS. 3B and 3D. In the images of FIGS. 3B and 3D, a message "Touch the gradation part to be enlarged." Is described on the image of FIG. 3A. The menu image, the message, and the like are displayed by the data processing of the data processing unit 110.

  In this embodiment, a user operation of touching the screen is performed as a user operation for selecting (designating) a position in the image displayed on the screen. Then, the control unit 101 sets the range of interest according to a user operation of touching the screen. The display of the message prompts a user operation for setting the range of interest. The display prompting the user operation for setting the attention range is not limited to the display of the message. For example, a predetermined icon may be displayed as a display that prompts a user operation for setting a range of interest.

An example of a method of setting the attention range will be described. As described above, in this embodiment, the user operation of touching the screen is performed as the user operation of selecting the position of the image displayed on the screen. Touch panel 106 detects a user operation of touching the screen, control unit 101 detects a position (touch position) selected by the user operation, and detects an input level M corresponding to the detected position. The input level M corresponding to the touch position is the input level of the pixel displayed at the touch position. Then, the control unit 101 determines and sets a gradation range of a predetermined width centered on the input level M as a target range (target gradation range). Although the width of the range of interest is not particularly limited, it is assumed in the present embodiment that the width of the range of interest is 60.
Note that the input level M corresponding to the touch position may be an average value of gradation values in a gradation range having a predetermined width around the input level of the pixel displayed at the touch position. Further, the input level M corresponding to the touch position may be an average value of pixel values of a region of a predetermined size including a pixel displayed at the touch position.

  In FIG. 3B, a bright cloud is touched. In this case, as shown in FIG. 4B, the input level on the high gradation side is detected as the input level M, and the gradation range on the high gradation side is set as the range of interest. In FIG. 3D, a dark house is touched. In this case, as shown in FIG. 4D, the input level on the low gradation side is detected as the input level M, and the gradation range on the low gradation side is set as the range of interest. 4 (B) and 4 (D), the input level N1 is the minimum value of the input level in the range of interest, and the input level N2 is the maximum value of the input level in the range of interest. The input level N1 is obtained by subtracting 30 from the input level M, and the input level N2 is obtained by adding 30 to the input level M.

  The method of setting the range of interest is not particularly limited. For example, an input level according to a user operation for setting the range of interest may correspond to a position different from the center of the range of interest. Specifically, an attention range in which the input level according to the user operation is the minimum value may be set, or an attention range in which the input level according to the user operation has the maximum value may be set. The width of the range of interest need not be a fixed width. The user operation for setting the attention range is not limited to the user operation of touching the screen. For example, a user operation of selecting a position of an image displayed on the screen using an up / down / left / right button (not shown) may be performed to set a range of interest. The user operation for setting the attention range may not be the user operation for selecting the position of the image displayed on the screen. For example, a user operation for designating (inputting) an input level may be performed, and a gradation range including the input level designated by the user operation may be set as the range of interest. A user operation for designating both the minimum value and the maximum value of the input level in the attention range may be performed. That is, a user operation for designating a range of interest may be performed.

  An example of a method for improving the gradation of the attention range will be described. The control unit 101 sets (changes) the conversion characteristics of the gradation conversion process based on the range of interest. Thereby, the input image data is converted into display image data (processed image data) in which the gradation of the attention range is higher than the predetermined gradation. The predetermined gradation is the gradation of display image data when a predetermined conversion characteristic (GLUT1 in FIG. 4A) is used. In the present embodiment, the control unit 101 sets the conversion characteristic so that the ratio of the attention corresponding range of the display image data (the gradation range corresponding to the attention range) to the entire gradation range of the display image data becomes a predetermined value. I do. Although the predetermined value is not particularly limited, in the present embodiment, it is assumed that the predetermined value is 70%.

  When the range of interest in FIG. 4B is set, the conversion characteristic GLUT2 in FIG. 4C is set. When the attention range in FIG. 4D is set, the conversion characteristic GLUT3 in FIG. 4E is set. 4A to 4E, the lower limit of the output level is 0%, and the upper limit of the output level is 100%. As shown in FIGS. 4B and 4D, in the conversion characteristic GLUT1, the input level N1 is associated with the output level L1, and the input level N2 is associated with the output level L2. On the other hand, as shown in FIGS. 4C and 4E, in the conversion characteristics GLUT2 and 3, the output level S1 is associated with the input level N1, and the output level S2 is associated with the input level N2. ing. The value obtained by subtracting the output level S1 from the output level S2 is 70%.

  As shown in FIGS. 4 (B) to 4 (E), the corresponding attention range of the conversion characteristics GLUT2 and GLUT3 (the gradation range from the output level S1 to the output level S2) is the corresponding attention range of the conversion characteristic GLUT1 (the output level). (The gradation range from L1 to the output level L2). Therefore, by using the conversion characteristics GLUT2 and GLUT3, it is possible to obtain display image data in which the gradation of the attention range is higher than a predetermined gradation (gradation when the conversion characteristic GLUT1 is used).

Further, as shown in FIGS. 4B to 4E, the remaining gradation range of the conversion characteristics GLUT2 and GLUT3 (the gradation range other than the corresponding attention range) is larger than the remaining gradation range of the conversion characteristic GLUT1. Is also narrow. Therefore, by using the conversion characteristics GLUT2 and GLUT3, display image data in which the gradation in a gradation range other than the range of interest is lower than the predetermined gradation is obtained.

  By switching the conversion characteristic of the gradation conversion processing from the conversion characteristic GLUT1 to the conversion characteristics GLUT2 and GLUT3, the image displayed on the screen is switched. Here, a case is considered where an image is displayed at the set display luminance. In this case, the conversion characteristic of the gradation conversion processing is switched from the conversion characteristic GLUT1 to the conversion characteristic GLUT2, so that the user perceives the image of FIG. 3C as the image displayed on the screen. In the image of FIG. 3C, the gradation of the cloud is higher than that of FIG. Then, the user can grasp the existence of the two clouds by perceiving the image of FIG. The existence of the two clouds cannot be grasped from the image of FIG. Further, by switching the conversion characteristic of the gradation conversion processing from the conversion characteristic GLUT1 to the conversion characteristic GLUT3, the user perceives the image of FIG. 3E as the image displayed on the screen. In the image of FIG. 3E, the gradation of the house is higher than the gradation of FIG. Then, the user can grasp the presence of the window by perceiving the image of FIG. The existence of the window cannot be grasped from the image of FIG.

The method for setting the display brightness is not particularly limited. For example, the display luminance is set so that a predetermined pixel value (white pixel value or the like) of the display image data is displayed at a desired display luminance. The set display brightness may be a predetermined display brightness (fixed brightness) or a display brightness that can be changed according to a user operation or the like. In this embodiment, it is assumed that the display luminance is set in advance so that white is displayed at 400 cd / m ² .

  The method of improving the gradation of the range of interest is not particularly limited. For example, the ratio of the attention corresponding range of the display image data to the entire gradation range of the display image data may change depending on the attention range. As a user operation for setting the range of interest, a user operation for specifying a conversion characteristic may be performed.

  An example of a method for canceling the dynamic range assist mode will be described. In the images of FIGS. 3C and 3E, an assist release button is arranged. When a user operation of touching the assist release button is performed, the control unit 101 releases the dynamic range assist and returns the conversion characteristics to the conversion characteristics GLUT1. Thereby, the image displayed on the screen is returned to the image of FIG.

  In human visual characteristics, the visibility of the gradation on the high gradation side decreases with an increase in display luminance. Therefore, if the set display brightness is maintained, the user can perceive only two clouds as shown in FIG. 3C, although there are three clouds in the image displayed on the screen. Further, in the human visual characteristics, the visibility with respect to the gradation on the low gradation side is reduced due to a decrease in display luminance. Therefore, if the set display luminance is maintained, the user cannot perceive the boundary between the roof of the house and the wall of the house, as shown in FIG. As described above, if the set display luminance is maintained, when a part of the gradation range of the input image data is displayed with high gradation, the part cannot be visually recognized with sufficiently high gradation. .

  Therefore, the control unit 101 controls the display luminance of the image displayed on the screen based on the range of interest. An example of a display luminance control method will be described. FIG. 5 is a flowchart illustrating an example of a display luminance control method. The flowchart of FIG. 5 is started according to the setting of the dynamic range assist mode.

First, in S501, the control unit 101 sets a range of interest. Next, in S502, the control unit 101 compares the input level representing the attention range set in S501 with threshold values α and β. The input level representing the attention range is the input level M according to the user operation. The threshold α is smaller than the threshold β. For example, the threshold α is 60 and the threshold β is 195. If the input level M is equal to or larger than the threshold β, the process proceeds to S503. If the input level M is smaller than the threshold α, the process proceeds to S504. If the input level M is equal to or more than the threshold α and less than the threshold β, the process proceeds to S505.

  Note that the input level representing the attention range may be an input level different from the input level M. The thresholds α and β may be predetermined values (fixed values), or may be values that can be changed according to a user operation or the like. The threshold α may be equal to the threshold β.

In S503, control unit 101 controls the display luminance of the image displayed on the screen to a display luminance lower than the set display luminance (light emission luminance reduction control). In this embodiment, the light emission brightness reduction control, as white display luminance is reduced from 400 cd / ^{m 2} to 200 cd / ^{m 2,} the emission luminance of the backlight unit 108 is reduced. For example, the emission luminance of the backlight unit 108 is reduced by reducing the value (current value, voltage value, etc.) of the backlight drive signal. When the backlight drive signal is a pulse signal, the emission luminance of the backlight unit 108 is reduced by reducing at least one of the pulse width and the pulse amplitude of the backlight drive signal. Thereafter, the process proceeds to S505. The display luminance after the emission luminance reduction control may be a predetermined display luminance (fixed luminance) or a display luminance that can be changed according to a user operation or the like. The pulse signal is also called a PWM (Pulse Width Modulation) signal.

In S504, control unit 101 controls the display luminance of the image displayed on the screen to a display luminance higher than the set display luminance (light emission luminance increase control). In this embodiment, the light emission luminance increase control, white display luminance so increased from 400 cd / ^{m 2} to 800 cd / ^{m 2,} the emission luminance of the backlight unit 108 is enhanced. For example, by increasing the value (current value, voltage value, etc.) of the backlight drive signal, the light emission luminance of the backlight unit 108 can be increased. When the backlight drive signal is a pulse signal, the emission luminance of the backlight unit 108 can be increased by increasing at least one of the pulse width and the pulse amplitude of the backlight drive signal. Thereafter, the process proceeds to S505. The display luminance after the emission luminance increase control may be a predetermined display luminance (fixed luminance) or a display luminance that can be changed according to a user operation or the like.

  In step S505, the control unit 101 sets the conversion characteristics of the gradation conversion process based on the range of interest set in step S501 (switches the conversion characteristics).

  When the range of interest in FIG. 4B is set, the input level M is larger than the threshold value β, so that the process proceeds from S502 to S503, and the emission luminance reduction control is performed. Then, in S505, the conversion characteristic of the gradation conversion processing is switched to the conversion characteristic GLUT2 in FIG. 4C, and the image displayed on the screen is switched. As a result, the user perceives the image in FIG. 6A as the image displayed on the screen. By the light emission luminance reduction control, the visibility of the gradation on the low gradation side is improved. Therefore, in the image of FIG. 6A, the gradation of the cloud is higher than the gradation of FIG. 3C. Then, the user can grasp the existence of the three clouds by perceiving the image of FIG. The existence of two clouds can be grasped from the image of FIG. 3C, but the existence of three clouds cannot be grasped from the image of FIG. As described above, when the range of interest is the range of gradation on the high gradation side, the gradation of the range of interest is enhanced and the display luminance is reduced. As a result, the range of interest can be visually recognized with sufficiently high gradation.

When the range of interest in FIG. 4D is set, the input level M is smaller than the threshold α, so that the process proceeds from S502 to S504, and the emission luminance increase control is performed. And S5
At 05, the conversion characteristic of the gradation conversion processing is switched to the conversion characteristic GLUT3 of FIG. 4E, and the image displayed on the screen is switched. As a result, the user perceives the image of FIG. 6B as the image displayed on the screen. The visibility of the gradation on the high gradation side is enhanced by the emission luminance increase control. Therefore, in the image of FIG. 6B, the gradation of the house is higher than the gradation of FIG. Then, the user can grasp the boundary between the roof of the house and the wall of the house by perceiving the image of FIG. 6B. The boundary between the roof of the house and the wall of the house cannot be grasped from the image of FIG. As described above, when the range of interest is the range of gradation on the low gray scale side, the gradation of the range of interest is enhanced and the display luminance is enhanced. As a result, the range of interest can be visually recognized with sufficiently high gradation.

  Note that each of the emission luminance reduction control and the emission luminance increase control is not limited to the control of the emission luminance of the backlight unit 108. For example, each of the emission luminance reduction control and the emission luminance increase control may be control of image processing (such as luminance correction processing of the luminance / contrast correction unit 205) on the processed image data. Each of the light emission luminance reduction control and the light emission luminance increase control may be one of the control of the light emission luminance of the backlight unit 108 and the image processing for the processed image data, or may be the control of both of them. One of the control of the light emission luminance of the backlight unit 108 and the image processing of the processed image data may be performed as light emission luminance reduction control, and the other control may be performed as light emission luminance increase control.

When the input level M is equal to or more than the threshold value α and less than the threshold value β, the attention range can be visually recognized with sufficiently high gradation even if the emission luminance reduction control or the emission luminance increase control is not performed. Therefore, as described above, the processing proceeds from S502 to S505 without performing the emission luminance reduction control in S503 and the emission luminance increase control in S504. Then, the control unit 101 controls the display luminance of the image displayed on the screen to the set display luminance. Specifically, the control unit 101 maintains the light emission luminance of the backlight unit 108 such that the white display luminance is maintained at 400 cd / m ² .

  As described above, according to the present embodiment, the emission luminance reduction control is performed when the input level representing the attention range is equal to or higher than the first threshold, and the input level representing the attention range is less than the second threshold. In some cases, emission luminance increase control is performed. The second threshold is equal to or less than the first threshold. Accordingly, even when the range of interest is a range of gradation on the high gradation side, when the range of interest is a range of gradation on the side of low gradation, the range of interest can be visually recognized with sufficiently high gradation. it can. Note that only one of the emission luminance reduction control and the emission luminance increase control may be performed.

  In the case where the present invention is realized by a self-luminous display device such as an organic EL display device, the control of the light emission luminance of the backlight unit 108 is replaced with the control of the organic EL light source (light emitting element) of the organic EL display panel. The emission luminance may be controlled. For example, the luminance of the organic EL light source may be controlled by changing the drive current value or the drive voltage value of the organic EL light source.

  In S505, the case where the conversion characteristic of the gradation conversion processing is switched from the conversion characteristic GLUT1 to GLUT2 or GLUT3 according to the input level M corresponding to the touch position has been described, but the present invention is not limited to this. For example, regardless of the input level M corresponding to the touch position, the conversion characteristic GLUT1 of the gradation conversion processing may always be used, and the luminance reduction processing and the luminance increase processing in S503 and S504 may be performed. In this case, an image in the range of interest can be confirmed at a suitable display luminance while faithfully reproducing the gradation characteristics of the input image data (captured image data).

<Example 2>
Hereinafter, a second embodiment of the present invention will be described. In the first embodiment, the gradation value of the input image data,
The example in which the gradation value of the processed image data, the gradation value of the display image data, and the like are 8-bit values has been described. In this embodiment, an example will be described in which the number of bits of the gradation value of the input image data is larger than the number of bits of the gradation value of the processed image data, the gradation value of the display image data, and the like. Specifically, it is assumed that the number of bits of the gradation value of the input image data is 12 bits. Then, it is assumed that image data having a gradation value of 8 bits is generated as the gradation value of the processed image data, the gradation value of the display image data, and the like. Hereinafter, points different from the first embodiment (configuration, processing, and the like) will be described in detail, and description of the same points as the first embodiment will be omitted. When the number of bits of the gradation value of the input image data is larger than the number of bits of the gradation value of the display image data, the dynamic range of the luminance (gradation) of the input image data is In other words, it is wider than the dynamic range of ()).

  The data processing unit 110 according to the present embodiment converts input image data having a gradation value of 12 bits into compressed image data having a gradation value of 8 bits. Specifically, the data processing unit 110 converts the input image data into compressed image data such that the tone values of the input image data outside the range of interest are limited to the tone values inside the range of interest. Then, the data processing unit 110 outputs the compressed image data (specifically, YCbCr data corresponding to the compressed image data) to the display processing unit 111.

  FIGS. 7A and 8A show an example of the gradation characteristics of the input image data. The horizontal axis in FIGS. 7A and 8A indicates the input luminance (the luminance of the input image data), and the vertical axis in FIGS. 7A and 8A indicates the gradation value (input level) of the input image data. ). The input luminance can also be referred to as “luminance assumed in input image data”, “subject luminance”, and the like. FIGS. 7A and 8A show an input level M at the center of the range of interest, a minimum value N1 of the input level in the range of interest, and a maximum value N2 of the input level in the range of interest. FIGS. 7A and 8A also show an input luminance range (a range of input luminance) corresponding to the range of interest. In the examples of FIGS. 7A and 8A, the attention range is set such that the input luminance range having a predetermined width is associated with the attention range. 7A and 8A can be set based on, for example, the input level M and the gradation characteristics of the input image data. In the data processing unit 110, an input level lower than the input level N1 is converted into the input level N1, and an input level higher than the input level N2 is converted into the input level N2.

  The display processing unit 111 according to the present embodiment converts the compressed image data into processed image data, and generates display image data. The display processing unit 111 uses a conversion characteristic based on the gradation characteristic of the input image data in the range of interest as the conversion characteristic of the gradation conversion processing. Specifically, the display processing unit 111 uses a conversion characteristic corresponding to an inverse characteristic of a characteristic indicating a change in input level with respect to a change in input luminance in the range of interest as a conversion characteristic of the gradation conversion processing. Thereby, the input image data is converted into display image data (processed image data) in which the gradation of the attention range is higher than the predetermined gradation. In this embodiment, the conversion characteristic of the gradation conversion processing is a conversion characteristic for converting the gradation value of the compressed image data into the gradation value of the processed image data.

  When the attention range in FIG. 7A is set, the conversion characteristic GLUT4 in FIG. 7B is set. When the attention range of FIG. 8A is set, the conversion characteristic GLUT5 of FIG. 8B is set. The conversion characteristics GLUT4 and GLUT5 correspond to the inverse characteristic of the characteristic indicating the change in the input range with respect to the change in the input luminance in the range of interest. Specifically, the horizontal axis (input level) in FIGS. 7B and 8B corresponds to the vertical axis (input level) in FIGS. 7A and 8A. ) And 8 (B) correspond to the horizontal axis (input luminance) in FIGS. 7 (A) and 8 (A). As shown in FIGS. 7B and 8B, in the conversion characteristics GLUTs 4 and 5, the output level 0% is used as the output level S1 corresponding to the input level N1. Then, the output level 100% is used as the output level S2 corresponding to the input level N2.

  Also in the present embodiment, the emission luminance reduction control is performed when the input level M is equal to or greater than the threshold value β, and the emission luminance increase control is performed when the input level M is less than the threshold value α. When the range of interest in FIG. 7A is set, the input level M is smaller than the threshold α, so that the light emission luminance increase control is performed. When the attention range in FIG. 8A is set, since the input level M is larger than the threshold value β, the emission luminance reduction control is performed.

  As described above, in the present embodiment, similarly to the first embodiment, the emission luminance reduction control and the emission luminance increase control are executed as necessary. Thereby, the attention range can be visually recognized with sufficiently high gradation.

  Note that instead of the conversion characteristics shown in FIGS. 7B and 8B, a gradation conversion process may be performed using a conversion characteristic GLUT 6 as shown in FIG. When the conversion characteristics shown in FIGS. 7B and 8B are used, the inverse characteristics of a part of the range of interest in the entire range of the gradation characteristics of the input image data are used. However, the conversion characteristics GLUT6 shown in FIG. Is used, the inverse characteristic of the entire range of the gradation characteristic of the input image data is used.

<Example 3>
Hereinafter, a third embodiment of the present invention will be described. In this embodiment, an example will be described in which external light (environmental light; natural light, illumination light, and the like) for the display device is further considered. In the following, differences (configuration, processing, etc.) from the first embodiment will be described in detail, and description of the same points as the first embodiment will be omitted.

  FIG. 9 is a block diagram illustrating a configuration example of the imaging apparatus according to the present embodiment. The imaging apparatus according to the present embodiment includes the plurality of functional units of the first embodiment (FIG. 1) and a luminance sensor 901. The luminance sensor 901 detects the luminance of external light with respect to the imaging device, and outputs a detection value to the control unit 101.

  In the present embodiment, the control method of the display luminance is different from the first embodiment. FIG. 10 is a flowchart illustrating an example of the display luminance control method according to the present embodiment. First, the processing of S1001 and S1002 is performed. The processing in S1001 and S1002 is the same as the processing in S501 and S302 in the first embodiment (FIG. 5). If the input level M is equal to or larger than the threshold β, the process proceeds to S1003, and if the input level M is smaller than the threshold α, the process proceeds to S1004. If the input level M is equal to or larger than the threshold α and smaller than the threshold β, the process proceeds to S1007. The processing in S1007 is the same as the processing in S505 in the first embodiment.

  In S1003, control unit 101 determines whether or not the detection value (detected luminance) of luminance sensor 901 is less than threshold value B. If the detected value is less than the threshold value B, the process of S1005 is performed, and the process proceeds to S1007. The processing in S1005 is the same as the processing in S503 (light emission luminance reduction control) in the first embodiment. If the detected value is equal to or larger than the threshold B, the process proceeds to S1007 without performing the light emission luminance reduction control in S1005. The threshold value B is a value for determining whether the use environment of the imaging device is a bright environment such as the outdoors, and is, for example, 10,000 lux. The threshold value B may be a predetermined value (fixed value) or a value that can be changed according to a user operation or the like.

  If the detection value is equal to or greater than the threshold value B, that is, if the light emission luminance reduction control is performed when the environment in which the imaging device is used is bright, the visibility (viewability) of the image displayed on the screen is reduced. . Specifically, since the image displayed on the screen is too dark, the user cannot grasp the angle of view (imaging range), the composition, and the like even by looking at the image displayed on the screen. Therefore, in this embodiment, the emission luminance reduction control is omitted in such a case. Thereby, a decrease in visibility (a decrease in visibility of an image displayed on the screen) due to the emission luminance reduction control can be suppressed.

  In S1004, control unit 101 determines whether or not the detection value of luminance sensor 901 is equal to or greater than threshold value A. If the detected value is equal to or larger than the threshold value A, the process of S1006 is performed, and the process proceeds to S1007. The processing in S1006 is the same as the processing in S504 (light emission luminance increase control) in the first embodiment. If the detected value is less than the threshold value A, the process proceeds to S1007 without performing the emission luminance increase control in S1006. The threshold value A is a value for determining whether the use environment of the imaging apparatus is a dark environment such as at night, and is, for example, 100 lux. The threshold value A may be a predetermined value (fixed value) or a value that can be changed according to a user operation or the like. Threshold A may be equal to threshold B.

  If the detected value is less than the threshold value A, that is, if the emission luminance increase control is performed in a dark environment where the imaging device is used, the visibility (viewability) of the image displayed on the screen is reduced. . Specifically, since the image displayed on the screen is too bright, the user feels glare and cannot see the image displayed on the screen with high visibility. Therefore, in this embodiment, the emission luminance increase control is omitted in such a case. As a result, a decrease in visibility due to emission luminance increase control can be suppressed. In addition, when the environment in which the imaging device is used is a dark environment, the visibility of the gradation on the low gradation side is high. Therefore, even if the emission luminance increase control is omitted, the attention range on the low gradation side can be visually recognized with sufficiently high gradation.

  As described above, according to the present embodiment, similarly to the first embodiment, the emission luminance reduction control and the emission luminance increase control are executed as necessary. Thereby, in various cases, the range of interest can be visually recognized with sufficiently high gradation. Further, since the light emission luminance reduction control and the light emission luminance increase control are appropriately omitted according to the luminance of the external light, it is possible to suppress a decrease in visibility due to the light emission luminance reduction control and the light emission luminance increase control.

  Each functional unit of the first to third embodiments may be individual hardware or may not be. The functions of two or more functional units may be realized by common hardware. Each of a plurality of functions of one functional unit may be realized by individual hardware. Two or more functions of one functional unit may be realized by common hardware. Also, each functional unit may or may not be realized by hardware. For example, the device may have a processor and a memory in which a control program is stored. Then, the functions of at least some of the functional units of the device may be realized by the processor reading out the control program from the memory and executing the control program.

  Embodiments 1 to 3 are merely examples, and configurations obtained by appropriately modifying or changing the configurations of Embodiments 1 to 3 within the scope of the present invention are also included in the present invention. A configuration obtained by appropriately combining the configurations of Embodiments 1 to 3 is also included in the present invention.

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

  101: control unit 105: liquid crystal display unit 204: gradation conversion unit

Claims (15)

Display means for displaying an image based on display image data generated from the input image data,
Control means for controlling the emission luminance of the light source of the display means,
Detecting means for detecting a user operation for specifying a position in the image;
With
The control means,
When the gradation value of the input image data corresponding to the position specified by the user operation is equal to or greater than a first threshold, the light emission luminance of the light source of the display unit is set to a light emission luminance lower than the set light emission luminance. A first control to control ;
When the tone value of the input image data corresponding to the position specified by the user operation is less than a second threshold, the light emission luminance of the light source is controlled to a light emission luminance higher than a set light emission luminance . Two controls,
Do at least one of
The second threshold is less than the first threshold,
The control unit sets the light emission luminance of the light source when a gradation value of the input image data corresponding to the position designated by the user operation is equal to or greater than the second threshold and less than the first threshold. A display device, wherein the luminance is controlled to be higher. The display device according to claim 1 , wherein the set emission luminance is a predetermined fixed luminance. The gradation value corresponding to the designated position in the image is a gradation value representing a gradation range of interest including a gradation value of the input image data at the designated position in the image. The display device according to claim 1 or 2 , wherein: The display device according to claim 3 , wherein the gradation value representing the target gradation range is a gradation value at the center of the target gradation range. Conversion means for performing a gradation conversion process on the input image data to generate the display image data;
With
The gradation conversion process, according to claim 1 to claim 4, characterized in that a treatment for increasing gradation of interest tonal range that includes the gradation value corresponding to the specified position in the image The display device according to claim 1. The gradation conversion process enhances the gradation of the target gradation range so that the ratio of the gradation range corresponding to the target gradation range to the entire gradation range of the display image data becomes a predetermined value. The display device according to claim 5 , wherein the display device is a process. The gradation conversion processing restricts a gradation value outside the target gradation range of the input image data to a gradation value inside the target gradation range, and performs a conversion of the input image data in the target gradation range. 6. The display device according to claim 5 , wherein the process is a process using a conversion characteristic based on a gradation characteristic. The conversion characteristic, according to claim 7, characterized in that the in the target gradation range corresponding to the inverse characteristic of the characteristic showing a change in gradation values of the input image data with respect to a change in luminance of the input image data Display device. The display device according to any one of claims 5 to 8 , wherein the number of bits of the input image data is larger than the number of bits of the display image data. The display means,
Light emitting means having a light source;
A display panel that displays the image by transmitting light emitted from the light emitting unit based on the display image data,
The display device according to any one of claims 1 to 9 , further comprising: Detecting means for detecting the brightness of the external light,
The control means,
When the gradation value corresponding to the designated position in the image is equal to or greater than the first threshold and the luminance detected by the detecting unit is less than a third threshold, the light emission of the light source is performed. Controlling the luminance to a light emission luminance lower than the set light emission luminance;
When the gradation value corresponding to the designated position in the image is equal to or greater than the first threshold, and the luminance detected by the detection unit is equal to or greater than the third threshold, the display device according to claim 1, the light emission luminance, and controlling the set emission luminance. Before Symbol control means,
When the gradation value corresponding to the designated position in the image is less than the second threshold value and the luminance detected by the detection means is equal to or greater than a fourth threshold value, Controlling the luminance to a higher luminance than the set luminance;
When the gradation value corresponding to the designated position in the image is less than the second threshold, and the luminance detected by the detection unit is less than the fourth threshold, Controlling the emission brightness to the set emission brightness ,
The display device according to claim 11 , wherein the fourth threshold value is equal to or less than the third threshold value . Detecting means for detecting the brightness of the external light,
The control means,
When the gradation value corresponding to the designated position in the image is less than the second threshold value and the luminance detected by the detection means is equal to or greater than a fourth threshold value, Controlling the luminance to a higher luminance than the set luminance;
When the gradation value corresponding to the designated position in the image is less than the second threshold, and the luminance detected by the detection unit is less than the fourth threshold, the display device according to claim 1, the light emission luminance, and controlling the set emission luminance. A display step of displaying on the display means an image based on the display image data generated from the input image data,
A control step of controlling the light emission luminance of the light source of the display means,
A detecting step of detecting a user operation for designating a position in the image;
Has,
In the control step,
When the gradation value of the input image data corresponding to the position specified by the user operation is equal to or greater than a first threshold, the light emission luminance of the light source of the display unit is set to a light emission luminance lower than the set light emission luminance. A first control to control ;
When the tone value of the input image data corresponding to the position specified by the user operation is less than a second threshold, the light emission luminance of the light source is controlled to a light emission luminance higher than a set light emission luminance . Two controls,
Do at least one of
The second threshold is less than the first threshold,
In the control step, when the gradation value of the input image data corresponding to the position designated by the user operation is equal to or more than the second threshold and less than the first threshold, the light emission luminance of the light source is set. A display method characterized by controlling light emission luminance to be high. A program for causing a computer to execute each step of the display method according to claim 14.

Images