JP2011128458A - Display control device, display control method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption while enhancing visibility. <P>SOLUTION: A light emission quantity calculation part 19 is configured to perform a light emission quantity calculating processing in accordance with a corrected maximum pixel value, as a light emission quantity calculating processing to calculate the quantity of light to be emitted from a light source 32. When a power saving mode is selected as a display mode, the light emission quantity calculation part 19 calculates the light emission quantity equal to or lower than a reference light emission quantity as the light emission quantity of the light source in accordance with the corrected maximum pixel value. When a visibility enhancing mode is selected as the display mode, the light emission quantity calculation part 19 calculates the reference light emission quantity or the light emission quantity larger than the reference light emission quantity as the light emission quantity of the light source. An image correction part 18 is configured to perform as an image correction processing to correct the image, an image pixel value extension processing of the image in accordance with the corrected maximum pixel value obtained by correcting the maximum pixel value of the image, and perform gradation correction to suppress saturation of the pixel values from the corrected maximum pixel value to the maximum pixel value by the extension processing. This invention is applicable to a display system for displaying images. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display control device, a display control method, and a program, and in particular, for example, a display that can reduce power consumption and improve visibility in displaying an image. The present invention relates to a control device, a display control method, and a program.

  An example of a display device that displays an image using light from a light source is a liquid crystal display device.

  In a liquid crystal display device, an image is displayed by irradiating light from a backlight as a light source to a liquid crystal panel that transmits (or blocks) light according to an image.

  For example, in Patent Document 1, for a dark image, the amount of light emitted from the backlight is decreased and the amount of light reduction (blocking amount) in the liquid crystal panel is increased. For a bright image, the amount of light emitted from the backlight is increased. A display device is described that increases and reduces the amount of light loss in a liquid crystal panel.

  Further, for example, Patent Document 2 discloses a process in which an image signal is diffused in a bright direction, and the brightness of the backlight is darkened according to the diffusion amount of the image signal, or the tone distribution is concentrated in a brighter one. The image signal is diffused in the darker part and the backlight brightness is darkened by the diffused amount. If the tone distribution is concentrated in the middle part, it is darkened on the bright side. A display device is described that performs processing that diffuses to the side and does not change the luminance of the backlight.

JP 09-244548 A JP 2006-145836

  For example, as in the display device described in Patent Document 1, for a dark image, the light emission amount of the backlight is reduced and the light reduction amount of the light on the liquid crystal panel is increased, thereby reducing the power consumption of the display device. Can be reduced.

  In addition, for example, as in the display device described in Patent Document 2, a clear and easy-to-view image is displayed by diffusing an image signal and adjusting the luminance of the backlight, that is, the visibility of the image is improved. Can be made.

  However, in recent years, demands for reducing power consumption and improving visibility have increased.

  This invention is made | formed in view of such a condition, and makes it possible to reduce power consumption more and to improve visibility more.

  The display control device or program according to one aspect of the present invention has a maximum pixel value from a pixel value of a display target image that is an image to be displayed on a display device that displays an image using light from a light source. Maximum pixel value detecting means for detecting a maximum pixel value, correction amount setting means for setting a correction amount for correcting the maximum pixel value, and correcting the maximum pixel value according to the correction amount, being smaller than the maximum pixel value Maximum pixel value correction means for calculating the maximum pixel value of the value and a display mode for displaying an image on the display device, a power saving mode for reducing power consumption, or visibility of an image displayed on the display device Display mode setting means for setting a visibility improvement mode for improving the display target, and image correction processing for correcting the display target image, the pixel value of the display target image is extended according to the corrected maximum pixel value. And a light emission amount calculating unit for performing a process of calculating the light emission amount according to the corrected maximum pixel value as a light emission amount calculation process for calculating a light emission amount of light emitted from the light source. When the display mode is the power saving mode, the light emission amount calculation means calculates a light emission amount equal to or less than a reference light emission amount that is a preset reference light emission amount according to the corrected maximum pixel value. When the display mode is the visibility enhancement mode, the light emission amount calculating means calculates the reference light emission amount or a light emission amount larger than the reference light emission amount. The amount of light emitted from the light source is calculated, and the image correction means performs display control that also performs gradation correction that suppresses saturation of pixel values from the corrected maximum pixel value to the maximum pixel value due to the expansion as the image correction processing. Device or as a display control device, a program for causing a computer to function.

  A display control method according to one aspect of the present invention is a display target image that is an image to be displayed on the display device by a display control device that controls display of the image by a display device that displays an image using light from a light source. A maximum pixel value detecting step for detecting a maximum pixel value, which is the maximum pixel value, a correction amount setting step for setting a correction amount for correcting the maximum pixel value, and the correction of the maximum pixel value. A maximum pixel value correcting step for correcting according to the amount and calculating a corrected maximum pixel value smaller than the maximum pixel value, and a display mode for displaying an image on the display device, a power saving mode for reducing power consumption, or As a display mode setting step for setting a visibility enhancement mode for improving the visibility of an image displayed on the display device, and an image correction process for correcting the display target image, As the image correction step for performing the process of expanding the pixel value of the display target image according to the positive maximum pixel value and the light emission amount calculation process for calculating the light emission amount of the light emitted from the light source, the correction maximum pixel value is set. Accordingly, when the display mode is the power saving mode, the light emission amount calculating step includes a step of calculating the light emission amount in advance according to the corrected maximum pixel value. A light emission amount equal to or less than a reference light emission amount that is a set reference light emission amount is calculated as the light emission amount of the light source, and when the display mode is the visibility improvement mode, the light emission amount calculation step includes the reference light emission amount. A light emission amount or a light emission amount larger than the reference light emission amount is calculated as the light emission amount of the light source. In the image correction step, the maximum pixel value is calculated from the corrected maximum pixel value by the expansion. Suppressing tone correction saturation of pixel values to pixel value is also a display control method for performing as the image correction processing.

  In one aspect as described above, the maximum pixel value that is the maximum pixel value is detected from the pixel value of the display target image that is the target image to be displayed on the display device that displays the image using the light from the light source. On the other hand, a correction amount for correcting the maximum pixel value is set, the maximum pixel value is corrected according to the correction amount, and a corrected maximum pixel value having a value smaller than the maximum pixel value is calculated. In addition, as a display mode for displaying an image on the display device, a power saving mode for reducing power consumption or a visibility improvement mode for improving the visibility of an image displayed on the display device is set. Further, as image correction processing for correcting the display target image, processing for expanding the pixel value of the display target image is performed according to the corrected maximum pixel value, and the light emission amount of light emitted from the light source is calculated. As the light emission amount calculation processing, processing for calculating the light emission amount is performed according to the corrected maximum pixel value. When the display mode is the power saving mode, a light emission amount equal to or less than a reference light emission amount that is a preset reference light emission amount is calculated as the light emission amount of the light source according to the corrected maximum pixel value. When the display mode is the visibility improving mode, the reference light emission amount or a light emission amount larger than the reference light emission amount is calculated as the light emission amount of the light source. Further, in the image correction process, gradation correction is performed to suppress saturation of pixel values from the corrected maximum pixel value to the maximum pixel value due to the expansion.

  Note that the display control device may be an independent device or an internal block constituting one device.

  The program can be provided by being transmitted via a transmission medium or by being recorded on a recording medium.

  According to one aspect of the present invention, power consumption can be further reduced, and visibility can be further improved.

It is a block diagram which shows the structural example of one Embodiment of the display system to which this invention is applied. 3 is a block diagram illustrating a functional configuration example of a control unit 13. FIG. It is a figure which shows the histogram of the pixel value of a display target image. It is a figure which shows an expansion ratio characteristic and a light emission magnification characteristic. It is a figure which shows the MAX / Pm 'time expansion | extension input / output characteristic. It is a flowchart explaining a control process. It is a flowchart explaining a correction | amendment maximum pixel value calculation process. It is a flowchart explaining an image correction process. It is a flowchart explaining the light emission amount calculation processing. It is a figure which shows an expansion gradation conversion input / output characteristic. It is a flowchart explaining an image correction process. It is a flowchart explaining the process of a display mode setting. It is a flowchart explaining the process of a correction amount setting. It is a figure which shows a correction amount characteristic. It is a figure which shows the relationship between the correction amount setting mode, the display mode setting mode, and the display mode, the correction amount, the light emission magnification, the edge enhancement degree, and the color signal expansion rate. It is a block diagram which shows the structural example of one Embodiment of the computer to which this invention is applied.

  [Configuration example of one embodiment of a display system to which the present invention is applied]

  FIG. 1 is a diagram of a display system to which the present invention is applied (a system is a logical collection of a plurality of devices, regardless of whether each configuration device is in the same housing). It is a block diagram which shows the structural example of embodiment.

  The display system shown in FIG. 1 can be applied to any device that displays an image. However, the display system of FIG. 1 has a monitor such as a liquid crystal monitor for checking captured images and OSD (On Screen Display) such as a digital camera and a video camera, and has low power consumption, and This is particularly useful for mobile devices where outdoor visibility is important.

  The display system in FIG. 1 includes a display control device 10 and a display device 30.

  The display control device 10 is supplied with an image to be displayed on the display device 30 (hereinafter also referred to as a display target image) (data thereof), and the display control device 10 causes the display device 30 to display the display target image. Perform display control.

  That is, the display control device 10 includes an illuminance sensor 11, an A / D (Analog / Digital) conversion unit 12, a control unit 13, an operation unit 14, a histogram generation unit 15, a maximum pixel value detection unit 16, and a maximum pixel value correction unit 17. The image correction unit 18 and the light emission amount calculation unit 19.

  The illuminance sensor 11 detects (senses) the illuminance of external light, and supplies an analog illuminance signal representing the illuminance to the A / D converter 12.

  The A / D conversion unit 12 converts the illuminance signal from the illuminance sensor 11 into A / D conversion into digital illuminance data, and supplies it to the control unit 13.

  In addition to the illuminance data supplied from the A / D converter 12, the control unit 13 is supplied with an operation signal corresponding to a user operation from the operation unit 14.

  The control unit 13 includes a CPU 13A and a memory 13B, and controls each block constituting the display control device 10 according to illuminance data from the A / D conversion unit 12, an operation signal from the operation unit 14, and the like. Perform various processes.

  That is, in the control unit 13, the CPU 13A performs various processes by executing a program stored in the memory 13B. The memory 13B stores programs executed by the CPU 13A and data necessary for the operation of the CPU 13A.

  The operation unit 14 is operated by a user and supplies an operation signal corresponding to the operation to the control unit 13.

  For example, an image captured by an imaging unit (not shown) is supplied to the histogram generation unit 15 as a display target image.

  The histogram generation unit 15 generates a histogram of pixel values of the display target image for each display control unit that performs preset display control, such as one frame of the display target image or a plurality of continuous frames, and detects the maximum pixel value. Supply to unit 16.

  The maximum pixel value detection unit 16 detects the maximum pixel value that is the maximum pixel value from the pixel values of the display target image in the display control unit based on the histogram from the histogram generation unit 15, and sends the maximum pixel value correction unit 17 to the maximum pixel value correction unit 17. Supply.

  The maximum pixel value correction unit 17 is supplied with the maximum pixel value from the maximum pixel value detection unit 16 and is supplied with a correction amount for correcting the maximum pixel value from the control unit 13 as will be described later.

  The maximum pixel value correction unit 17 corrects the maximum pixel value from the maximum pixel value detection unit 16 according to the correction amount from the control unit 13, that is, for example, subtracts a positive correction amount from the maximum pixel value. Thus, the maximum pixel value is corrected, and a corrected maximum pixel value having a value smaller than the maximum pixel value is calculated.

  In addition, the maximum pixel value correction unit 17 may calculate a corrected maximum pixel value having a value smaller than the maximum pixel value, for example, by multiplying the maximum pixel value by a correction amount having a positive value less than 1.0. it can.

  The maximum pixel value correction unit 17 supplies the corrected maximum pixel value to the image correction unit 18 and the light emission amount calculation unit 19.

  Further, the maximum pixel value correction unit 17 performs image correction on the maximum pixel value from the maximum pixel value detection unit 16 (or a correction amount that is information that can be used together with the corrected maximum pixel value to obtain the maximum pixel value). Supply to unit 18.

  In addition to the maximum pixel value and the corrected maximum pixel value supplied from the maximum pixel value correcting unit 17, the image correction unit 18 is supplied with a display target image, and from the control unit 13, as will be described later. A display mode for displaying the display target image on the display device 30 is supplied.

  The image correction unit 18 performs image correction processing for correcting the display target image in the display control unit according to the display mode from the control unit 13, from the maximum pixel value correction unit 17 obtained from the display target image in the display control unit. In accordance with the corrected maximum pixel value, a process for expanding the pixel value of the display target image is performed.

  Then, the image correction unit 18 supplies the display target image after the image correction process to the display panel 33 described later of the display device 30.

  Note that the image correction unit 18 performs not only expansion of the pixel value of the display target image but also gradation correction for suppressing saturation of the pixel value from the corrected maximum pixel value to the maximum pixel value due to the expansion as the image correction processing. .

  Further, the image correction unit 18 also performs contour enhancement for enhancing the contour of the display target image as the image correction process.

  In addition to the corrected maximum pixel value supplied from the maximum pixel value correcting unit 17, the light emission amount calculating unit 19 is supplied with a display mode and a reference light emitting amount as will be described later.

  Here, the reference light emission amount is a reference light emission amount of light emitted from a light source 32 (to be described later) of the display device 30.

  In accordance with the corrected maximum pixel value from the maximum pixel value correction unit 17, the light emission amount calculation unit 19 performs a light emission amount calculation process for calculating the light emission amount of light emitted from the light source 32 according to the display mode from the control unit 13. A process for calculating the light emission amount is performed, and light emission amount information representing the light emission amount is supplied to the light source driving unit 31.

  Here, the light emission amount calculation unit 19 calculates a light emission magnification, which is a coefficient by which the reference light emission amount from the control unit 13 is multiplied, according to the corrected maximum pixel value from the maximum pixel value correction unit 17, and calculates the light emission magnification. By multiplying the reference light emission amount, the light emission amount of the light source 32 (the light emission amount of the light emitted from the light source 32) is calculated.

  In this way, the light emission magnification is multiplied by the reference light emission amount, and the multiplication result is the light emission amount of the light source 32, and thus represents the ratio of the light emission amount of the light source 32 to the reference light emission amount.

  The display device 30 includes a light source driving unit 31, a light source 32, and a display panel 33. Using the light from the light source 32, for example, the light is transmitted (blocked) according to a display target image, or The display target image is displayed by reflection.

  That is, the light source drive unit 31 drives the light source 32 according to the light emission amount information from the light emission amount calculation unit 19 and causes the light source 32 to emit light of the light emission amount represented by the light emission amount information.

  The light source 32 is, for example, an LED (Light Emitting Diode) or the like, and is driven by the light source driving unit 31 to emit (emit) light having a light emission amount (luminance) represented by the light emission amount information.

  The light emitted from the light source 32 is applied to the display panel 33.

  The display panel 33 is a liquid crystal panel, for example, and displays a display target image by transmitting (blocking) light from the light source 32 according to the display target image supplied from the image correction unit 18.

  [Functional configuration example of the control unit 13]

  FIG. 2 is a block diagram illustrating a functional configuration example of the control unit 13 of FIG.

  The functional configuration of FIG. 2 is realized by the CPU 13A of the control unit 13 executing a program.

  In FIG. 2, the control unit 13 includes a display mode setting unit 41, a correction amount setting unit 42, and a reference light emission amount setting unit 43.

  The display mode setting unit 41, the correction amount setting unit 42, and the reference light emission amount setting unit 43 include illuminance data from the A / D conversion unit 12 (FIG. 1) and an operation signal from the operation unit 14 (FIG. 1). Is supplied.

  The display mode setting unit 41 sets the display mode according to the illuminance data from the A / D conversion unit 12 and the operation signal from the operation unit 14 and supplies the display mode to the correction amount setting unit 42. And supplied to the light emission amount calculation unit 19 (FIG. 1).

  Here, as the display mode, there are a power saving mode for reducing power consumption of the display system (the display device 30) and a visibility improvement mode for improving the visibility of an image displayed on the display device 30.

  In the display mode setting unit 41, the display mode setting mode for setting the display mode includes a manual mode for setting the display mode according to an operation signal from the operation unit 14 and a display according to the illuminance data from the A / D conversion unit 12. There is an automatic mode to set the mode.

  Whether the display mode setting mode is the manual mode or the automatic mode can be set by operating the operation unit 14.

  The correction amount setting unit 42 sets the correction amount according to the illuminance data from the A / D conversion unit 12, the operation signal from the operation unit 14, and the display mode from the display mode setting unit 41, and the maximum pixel value correction unit 17. (FIG. 1).

  Here, in the correction amount setting unit 42, the correction amount setting mode for setting the correction amount includes a manual mode for setting the correction amount according to an operation signal from the operation unit 14, and a fixed value according to the display mode from the display mode setting unit 41. There are a fixed mode for setting the correction amount and a variable mode for setting the correction amount according to the illuminance data from the A / D converter 12.

  The correction amount setting mode can be set to any one of the manual mode, the fixed mode, and the variable mode by operating the operation unit 14.

  For example, the reference light emission amount setting unit 43 sets the light emission amount stored in advance in a built-in memory (not shown) as the reference light emission amount, and supplies the light emission amount calculation unit 19 (FIG. 1).

  In addition, the reference light emission amount setting unit 43 can set the reference light emission amount according to, for example, an operation signal from the operation unit 14. Further, the reference light emission amount setting unit 43 can set the reference light emission amount according to the illuminance data from the A / D conversion unit 12.

  [Processing of Histogram Generation Unit 15, Maximum Pixel Value Detection Unit 16, and Maximum Pixel Value Correction Unit 17]

  FIG. 3 is a diagram for explaining processing of the histogram generation unit 15, the maximum pixel value detection unit 16, and the maximum pixel value correction unit 17 in FIG.

  That is, FIG. 3 shows a histogram of pixel values of the display target image (in the display control unit) generated by the histogram generator 15 (FIG. 1).

  In FIG. 3, the horizontal axis represents the pixel value, and the vertical axis represents the frequency.

  In the histogram of FIG. 3, the pixel value Pm is the maximum among the pixel values of the display target image, and the maximum pixel value detection unit 16 (FIG. 1) uses the pixel value Pm as the maximum pixel value. Detected.

  In FIG. 3, Cp represents the correction amount set by the correction amount setting unit 42 (FIG. 2) of the control unit 13.

  In the maximum pixel value correction unit 17 (FIG. 1), the correction amount Cp is subtracted from the pixel value Pm, and a subtraction value Pm ′ obtained as a result is calculated as the corrected maximum pixel value.

  In FIG. 3, MAX represents the maximum value that the pixel value of the display target image can take.

  [Stretch rate characteristics and emission magnification characteristics]

  FIG. 4 is a diagram illustrating the expansion rate characteristic and the light emission magnification characteristic.

  In FIG. 4, the horizontal axis represents the corrected maximum pixel value Pm ′, and the vertical axis represents the expansion rate and the light emission magnification.

  Here, the expansion rate represents a magnification of how many times the pixel value is increased in the process of expanding the pixel value of the display target image, which is performed by the image correction unit 18 (FIG. 1) as the image correction process.

  In the image correction unit 18, the expansion rate is calculated using an expansion rate characteristic that represents a characteristic of the expansion rate that changes according to the corrected maximum pixel value Pm ′.

  Further, as described with reference to FIG. 1, the light emission magnification represents the ratio of the light emission amount of the light source 32 to the reference light emission amount, and changes in accordance with the corrected maximum pixel value Pm ′ in the light emission amount calculation unit 19 (FIG. 1). It is calculated using the light emission magnification characteristic representing the light emission magnification characteristic.

  FIG. 4 shows the expansion ratio characteristic and the light emission magnification characteristic used when the display mode is the power saving mode, and the expansion ratio characteristic and the light emission magnification characteristic used when the display mode is the visibility enhancement mode. Is shown.

  That is, FIG. 4A shows the expansion rate characteristic and the light emission magnification characteristic used when the display mode is the power saving mode, and FIG. 4B shows the expansion used when the display mode is the visibility enhancement mode. The rate characteristic and the light emission magnification characteristic are shown.

  Here, the expansion rate characteristic and the light emission magnification characteristic when the display mode is the power saving mode are also referred to as the expansion ratio characteristic # 1 and the light emission magnification characteristic # 1, respectively, and the display mode is the visibility improvement mode. In some cases, the expansion ratio characteristic and the light emission magnification characteristic are also referred to as the expansion ratio characteristic # 2 and the light emission magnification characteristic # 2, respectively.

  The expansion rate characteristic # 1 (FIG. 4A) in the power saving mode monotonously decreases with an increase in the corrected maximum pixel value Pm ′ and is a value larger than 1.0 times, for example, 2.0 times as a maximum value. At the same time, the characteristic is 1.0 times minimum.

  That is, in the expansion rate characteristic # 1, when the corrected maximum pixel value Pm ′ is a value equal to or less than (or less than) the predetermined threshold TH1, the expansion rate is a constant value of 2.0 times that is the maximum value of the expansion rate. It has become.

  Further, in the expansion rate characteristic # 1, when the corrected maximum pixel value Pm ′ is larger (or more) than the predetermined threshold value TH1, the expansion rate is 2.0 times in proportion to the corrected maximum pixel value Pm ′. The value decreases from

  In the expansion rate characteristic # 1, when the corrected maximum pixel value Pm ′ is the maximum value MAX that can be taken as the pixel value, the minimum value of the expansion rate is 1.0.

  Note that the pixel value after expansion, which is obtained by expanding the corrected maximum pixel value Pm ′ (the pixel value above) by the expansion rate times, is limited to the maximum value MAX that can be taken as the pixel value. The expansion rate is such that the pixel value after expansion of the corrected maximum pixel value Pm ′ does not exceed the maximum value MAX (or a value smaller by a minute value than the maximum value MAX).

  That is, in the expansion rate characteristic # 1, the threshold TH1 of the corrected maximum pixel value Pm ′ when the expansion rate is 2.0 times that is the maximum value of the expansion rate is MAX / 2 (below). Therefore, when the corrected maximum pixel value Pm ′ is equal to the threshold value TH1 = MAX / 2, the pixel value after expansion of the corrected maximum pixel value Pm ′ does not exceed the maximum value MAX (= MAX / 2 × 2.0). It is like that.

  In the expansion rate characteristic # 1, the expansion rate for the corrected maximum pixel value Pm ′ larger than the threshold value TH1 = MAX / 2 is MAX / Pm ′, and thus, the expansion rate is larger than the threshold value TH1 = MAX / 2. The pixel value after expansion of the corrected maximum pixel value Pm ′ is set to the maximum value MAX.

  The light emission magnification characteristic # 1 (first light emission magnification characteristic) (FIG. 4A) in the power saving mode is a characteristic that monotonously increases as the corrected maximum pixel value Pm ′ increases.

  In the light emission magnification characteristic # 1, the light emission magnification is a reciprocal of the expansion rate.

  Therefore, the light emission magnification characteristic # 1 is a characteristic in which 1/2 is the reciprocal of the maximum value of the expansion rate and the minimum value is 1.0, and 1.0 is the maximum value.

  On the other hand, the expansion rate characteristic # 2 (FIG. 4B) in the visibility enhancement mode is the same as the expansion rate characteristic # 1 in the power saving mode in FIG.

  Note that the expansion rate characteristic # 2 in the visibility enhancement mode is different from the expansion rate characteristic # 1 in the power saving mode, that is, for example, the maximum value of the expansion ratio is larger than that in the power saving mode. Etc. can be adopted.

  The light emission magnification characteristic # 2 (second light emission magnification characteristic) (FIG. 4B) in the visibility enhancement mode is a characteristic having 1.0 as a minimum value.

  In the light emission magnification characteristic # 2, the light emission magnification is 1.0 times, which is the minimum value, for the corrected maximum pixel value Pm ′ which is close to the maximum value MAX and less than the threshold value TH2 (> TH1) less than the maximum value MAX. It is a constant value, and for the corrected maximum pixel value Pm ′ greater than the threshold TH2, the light emission magnification is a value that increases with an increase in the corrected maximum pixel value Pm ′ greater than 1.0 times. Yes.

  Therefore, the light emission magnification characteristic # 2 is a characteristic that monotonously increases as the corrected maximum pixel value Pm ′ increases, and in this respect, is common with the light emission magnification characteristic # 1.

  When the display mode is the power saving mode, the image correction unit 18 (FIG. 1) calculates the expansion rate with respect to the corrected maximum pixel value Pm ′ according to the expansion rate characteristic # 1, and the pixel of the display target image with the expansion rate. Stretch the value.

  That is, the image correction unit 18 performs pixel value expansion by multiplying the pixel value of the display target image by the expansion rate.

  Further, in the power saving mode, the light emission amount calculation unit 19 (FIG. 1) calculates the light emission magnification with respect to the corrected maximum pixel value Pm ′ according to the light emission magnification characteristic # 1, and calculates the light emission amount of the light source 32 according to the light emission magnification. To do.

  That is, the light emission amount calculation unit 19 calculates the light emission amount of the light source 32 by multiplying the reference light emission amount by the light emission magnification.

  Here, in the light emission magnification characteristic # 1, since the maximum value of the light emission magnification is 1.0, the light emission amount equal to or less than the reference light emission amount is calculated as the light emission amount of the light source 32 in the power saving mode.

  On the other hand, when the display mode is the visibility enhancement mode, the image correction unit 18 (FIG. 1) calculates the expansion rate for the corrected maximum pixel value Pm ′ according to the expansion rate characteristic # 2, and uses the expansion rate as a display target. Extends the pixel value of the image.

  Further, in the visibility enhancement mode, the light emission amount calculation unit 19 (FIG. 1) calculates the light emission magnification with respect to the corrected maximum pixel value Pm ′ according to the light emission magnification characteristic # 2, and calculates the light emission amount of the light source 32 according to the light emission magnification. calculate.

  Here, in the light emission magnification characteristic # 2, since the light emission magnification is 1.0 or more, in the visibility improvement mode, the light emission amount of the light source 32 is a reference light emission amount or a light emission amount larger than the reference light emission amount. Calculated.

  As described above, when the display mode is the power saving mode, in the image correction unit 18, the expansion rate MAX / Pm ′ is 1.0 times or more according to the maximum correction pixel value Pm ′ according to the expansion rate characteristic # 1. (Or 2.0 times) is calculated, and image correction processing for expanding the display target image is performed at the expansion rate MAX / Pm ′.

  Further, the light emission amount calculation unit 19 calculates the reciprocal of the expansion rate MAX / Pm ′ as the light emission magnification according to the light emission amount characteristic # 1 and according to the corrected maximum pixel value Pm ′, and uses the light emission magnification as the reference light emission amount. Is multiplied to calculate the light emission amount of the light source 32.

  Accordingly, in the power saving mode, the display target image is expanded and brightened (the pixel value is increased), and the light emission amount of the light source 32 is reduced (darkened) from the reference light emission amount by the lightening amount. Therefore, power consumption can be reduced while maintaining the brightness of the display target image displayed on the display device 30.

  On the other hand, when the display mode is the visibility enhancement mode, the image correction unit 18 expands the expansion ratio MAX / Pm ′ (or 1.0 times or more) according to the correction maximum pixel value Pm ′ according to the expansion ratio characteristic # 2. 2.0 times) is calculated in the same manner as in the power saving mode, and image correction processing for expanding the display target image is performed at the expansion rate MAX / Pm ′.

  Furthermore, in the light emission amount calculation unit 19, in accordance with the light emission amount characteristic # 2, basically (unless the corrected maximum pixel value Pm ′ is close to the maximum value MAX and not less than the threshold value TH2), the light emission magnification is 1.0 times. Is calculated by multiplying the light emission magnification by the reference light emission amount, so that the reference light emission amount is calculated as the light emission amount of the light source 32.

  Therefore, the brightness of the display target image displayed on the display device 30 can be increased without increasing the light emission amount of the light source 32 from the reference light emission amount by the image correction process for expanding the display target image. The visibility (ease of viewing) of the display target image in an environment where the illuminance of outside light such as sunlight is large can be improved without increasing the power consumption.

  Further, the image correcting unit 18 calculates the expansion rate according to the expansion rate characteristic corresponding to the display mode among the expansion rate characteristics # 1 and # 2, and expands the pixel value of the display target image with the expansion rate. Since the image correction process is performed, it is not necessary to separately provide a block that performs the image correction process in the power saving mode and a block that performs the image correction process in the visibility enhancement mode.

  That is, the image correction processing in the power saving mode and the image correction processing in the visibility improvement mode can be performed by one image correction unit 18.

  Similarly, the light source calculation unit 19 calculates the light emission magnification according to the light emission magnification characteristic corresponding to the display mode among the light emission magnification characteristics # 1 and # 2, and multiplies the light emission magnification by the reference light emission amount. Since the light emission amount calculation process for obtaining the light emission amount of the light source 32 is performed, there is no need to separately provide a block that performs the light emission amount calculation process in the power saving mode and a block that performs the light emission amount calculation process in the visibility improvement mode. .

  That is, the light emission amount calculation process in the power saving mode and the light emission amount calculation process in the visibility improvement mode can be performed by one light source calculation unit 19.

  When the display mode is the visibility improvement mode and the corrected maximum pixel value Pm ′ is a value close to the maximum value MAX, the expansion rate MAX / Pm ′ calculated according to the expansion rate characteristic # 2 is Therefore, depending on the image correction process, the brightness of the display target image displayed on the display device 30 may be almost brighter than the brightness when the image correction process is not performed. Can not.

  Therefore, in the visibility enhancement mode, when the corrected maximum pixel value Pm ′ is a value equal to or greater than the threshold value TH2 that is close to the maximum value MAX, the light emission amount calculation unit 19 corrects the corrected maximum pixel value Pm ′ that is equal to or greater than the threshold value TH2. For, the light emission magnification greater than 1.0 is calculated according to the light emission magnification characteristic # 2 that increases with an increase in the corrected maximum pixel value Pm ′ greater than 1.0. Is multiplied by the reference light emission amount to calculate a light emission amount larger than the reference light emission amount as the light emission amount of the light source 32.

  As described above, when the corrected maximum pixel value Pm ′ is a value close to the maximum value MAX, the light emission amount larger than the reference light emission amount is calculated as the light emission amount of the light source 32, whereby the display device 30. The brightness of the display target image displayed on the screen can be increased, and the visibility of the display target image can be improved.

  [Extension of pixel value as image correction processing]

  FIG. 5 is a diagram for explaining pixel value expansion performed by the image correction unit 18 of FIG. 1 as image correction processing.

  Here, the pixel value of the display target image, which is the target of the image correction processing by the image correction unit 18, is also referred to as an input pixel value, and the pixel value after the image correction processing is also referred to as an output pixel value.

  FIG. 5 shows the relationship between input pixel values and output pixel values (hereinafter also referred to as input / output characteristics) when only pixel value expansion is performed as image correction processing.

  In the following, for the sake of simplicity, unless otherwise specified, it is assumed that the corrected maximum pixel value Pm ′ is larger than the threshold value TH1 = MAX / 2. Therefore, the expansion rate characteristic # 1 (or the expansion rate characteristic) Assume that the expansion rate calculated according to # 2) is MAX / Pm ′ as described in FIG.

  In FIG. 5, MAX / Pm ′ double expansion input / output characteristics indicate the expansion input / output characteristics for multiplying the input pixel value by the expansion ratio MAX / Pm ′.

  In FIG. 5, for reference, the input pixel value is expanded by 1.0, that is, the input / output characteristic when the input pixel value is used as it is as the output pixel value, Also shown is a normal expansion input / output characteristic which is an expansion input / output characteristic for multiplying the pixel value by MAX / Pm.

  As described above, the expansion rate of the pixel value expansion performed by the image correction unit 18 as the image correction processing is MAX / Pm ′, and the MAX / Pm′-fold expansion input / output characteristic is the expansion rate MAX / Pm ′. This represents the input / output characteristics of the image correction processing that performs expansion.

  On the other hand, in order to expand the pixel value of the display target image so that the pixel value (output pixel value) after the expansion does not become saturated, that is, does not exceed the maximum value MAX that can be taken as the pixel value. Therefore, it is necessary to set the expansion rate to MAX / Pm times or less.

  Therefore, when the pixel value is expanded so that the output pixel value is not saturated, the maximum value of the expansion rate is MAX / Pm times, and the expansion by this expansion rate MAX / Pm times is called normal expansion. Then, the normal expansion input / output characteristic represents the normal expansion input / output characteristic.

  Here, since the corrected maximum pixel value Pm ′ is smaller than the maximum pixel value Pm, the expansion rate MAX / Pm ′ is larger than the expansion rate MAX / Pm.

  Therefore, according to the expansion according to the MAX / Pm′-fold expansion input / output characteristics, in which the input pixel value is expanded by MAX / Pm ′, that is, the expansion performed by the image correction unit 18 (FIG. 1) as the image correction processing. The pixel value (output pixel value) of the display target image becomes larger than the expansion according to the normal expansion input / output characteristic (normal expansion) in which the input pixel value is expanded by MAX / Pm times.

  As described above, in the expansion performed as the image correction processing by the image correction unit 18 (FIG. 1), the expansion ratio is larger than that in the normal expansion, and therefore, the reciprocal of the expansion ratio is calculated as the light emission magnification. In the power saving mode, the light emission amount of the light source 32 is further reduced as compared with the normal extension, and as a result, the power consumption can be reduced as compared with the normal extension.

  Further, in the visibility enhancement mode, the brightness of the display target image displayed on the display device 30 is brighter than that in the normal expansion (since the brightness is increased), so the visibility is higher than in the normal expansion. Can also be improved.

  Note that the visibility of the display target image displayed on the display device 30 is that the light emission amount of the light source 32 is made larger than the reference light emission amount without expanding the pixel value of the display target image, that is, the light emission magnification is It can be improved only by making it larger than 1.0.

  However, when the light emission magnification is set higher than 1.0, the power consumption increases.

  On the other hand, in the visibility improvement mode, the pixel value of the display target image is expanded, and only when the corrected maximum pixel value Pm ′ is a value equal to or greater than the threshold value TH2, which is close to the maximum value MAX, In other cases, that is, when the corrected maximum pixel value Pm ′ is less than the threshold value TH2, the light emission magnification is set to 1.0 times. The power consumption can be reduced compared with the case of improving the visibility only by making the light emission magnification larger than 1.0 without performing the expansion of.

  [Control processing]

  FIG. 6 is a flowchart for explaining processing (control processing) performed by the control unit 13 of FIG.

  In the control unit 13 (FIG. 2), in step S11, the reference light emission amount setting unit 43 sets the reference light emission amount and supplies it to the light emission amount calculation unit 19 (FIG. 1), and the process proceeds to step S12.

  In step S12, the display mode setting unit 41 sets the display mode according to the illuminance data from the A / D conversion unit 12 and the operation signal from the operation unit 14, supplies the display mode to the correction amount setting unit 42, and performs image correction. The data is supplied to the unit 18 and the light emission amount calculation unit 19 (FIG. 1), and the process proceeds to step S13.

  In step S13, the correction amount setting unit 42 sets the correction amount according to the illuminance data from the A / D conversion unit 12, the operation signal from the operation unit 14, and the display mode from the display mode setting unit 41, and sets the maximum pixel. It supplies to the value correction | amendment part 17 (FIG. 1).

  And a process returns to step S11 and the same process is repeated hereafter.

  Note that the setting of the reference light emission amount, the display mode, and the correction amount is performed, for example, with the display control unit of the display target image as the minimum unit.

  [Correction Maximum Pixel Value Calculation Processing]

  FIG. 7 is a flowchart for explaining processing (corrected maximum pixel value calculation processing) performed by the histogram generation unit 15, the maximum pixel value detection unit 16, and the maximum pixel value correction unit 17 in FIG.

  In the following, in order to simplify the description, one frame is adopted as the display control unit of the display target image.

  In step S21, the maximum pixel value correction unit 17 determines whether or not the correction amount is supplied from the control unit 13. If it is determined that the correction amount is not supplied, the process skips step S22. The process proceeds to step S23.

  If it is determined in step S21 that the correction amount has been supplied from the control unit 13, the process proceeds to step S22, and the maximum pixel value correction unit 17 stores the control unit in a built-in memory (not shown). The correction amount from 13 is overwritten and stored, and the process proceeds to step S23.

  In step S23, the histogram generation unit 15 determines whether or not one frame of display target image (data) as a display control unit has been newly supplied, and one frame of display target image has not been supplied yet. If it is determined, the process returns to step S21.

  If it is determined in step S23 that one frame of the display target image has been supplied, the process proceeds to step S24, and the histogram generation unit 15 determines the pixel value of the newly supplied one frame of the display target image. Generate a histogram.

  Furthermore, the histogram generation unit 15 supplies the pixel value histogram of the display target image to the maximum pixel value detection unit 16, and the process proceeds from step S24 to step S25.

  In step S25, the maximum pixel value detection unit 16 detects the maximum pixel value Pm from the pixel value of the display target image based on the histogram from the histogram generation unit 15, supplies the maximum pixel value Pm to the maximum pixel value correction unit 17, and performs processing. Advances to step S26.

  In step S26, the maximum pixel value correcting unit 17 corrects the maximum pixel value from the maximum pixel value detecting unit 16 according to the latest correction amount stored in step S22, and calculates a corrected maximum pixel value Pm ′.

  Then, the maximum pixel value correction unit 17 supplies the corrected maximum pixel value to the image correction unit 18 and the light emission amount calculation unit 19, and the process returns to step S21. Thereafter, the same process is repeated.

  [Image correction processing]

  FIG. 8 is a flowchart for explaining image correction processing performed by the image correction unit 18 of FIG.

  In step S31, the image correction unit 18 selects an expansion rate characteristic corresponding to the display mode according to the latest display mode from the control unit 13, and the process proceeds to step S32.

  That is, when the display mode is the power saving mode, the image correction unit 18 selects the expansion rate characteristic # 1 (FIG. 4A) as the expansion rate characteristic corresponding to the display mode, and the display mode is the visibility enhancement mode. In this case, the expansion rate characteristic # 2 (FIG. 4B) is selected as the expansion rate characteristic corresponding to the display mode.

  As described with reference to FIG. 4, when the same characteristics are adopted as the expansion rate characteristics # 1 and # 2, the process of selecting the expansion rate characteristics in step S31 can be omitted.

  In step S32, the image correction unit 18 calculates the expansion rate for the corrected maximum pixel value Pm ′ in accordance with the corrected maximum pixel value Pm ′ from the maximum pixel value correction unit 17 according to the expansion rate characteristic corresponding to the display mode. Then, the process proceeds to step S33.

  In step S <b> 33, the image correction unit 18 pays attention to a frame of the display target image for which the histogram is generated by the histogram generation unit 15, which has not been subjected to image correction processing yet, and is the earliest in time. As the attention frame, expansion is performed to expand the pixel value of the attention frame in accordance with the expansion ratio with respect to the corrected maximum pixel value Pm ′.

  Here, when the pixel value before expansion of the frame of interest is referred to as an input pixel value, and the pixel value after expansion of the frame of interest is referred to as an output pixel value, the image correction process for expanding the pixel value of the frame of interest is: It can be said to be an image conversion process for converting an input pixel value into an output pixel value.

  Thereafter, the process proceeds from step S33 to step S34, and the image correction unit 18 performs a process of performing the edge enhancement of the frame of interest after the image conversion process at the edge enhancement degree corresponding to the display mode.

  Then, the image correction unit 18 supplies the display target image after the outline enhancement to the display panel 33, the process returns from step S34 to step S31, and the same process is repeated thereafter.

  Here, the edge enhancement degree represents the degree of edge enhancement in edge enhancement.

  For example, assuming that three types of “weak”, “medium”, and “strong” are prepared in order of increasing degree of edge enhancement, the edge enhancement degree corresponding to the display mode is set. When the display mode is the power saving mode, for example, “weak” or “medium” is adopted, and when the display mode is the visibility enhancement mode, for example, “strong” is adopted.

  Therefore, in the visibility enhancement mode, the degree of contour enhancement is stronger than in the power saving mode, and the contour is more emphasized in contour enhancement.

  In addition, the edge enhancement degree of edge enhancement performed by a general TV (television receiver) is adopted as the edge enhancement degree of “weak” or “medium”, and the edge enhancement degree is called a normal edge enhancement degree. Then, in the visibility enhancement mode, contour enhancement is performed with a contour enhancement degree stronger than the normal contour enhancement degree.

  Therefore, in the visibility enhancement mode, for example, a display target image in which edges and the like are emphasized excessively compared to a general TV is displayed.

  However, in the visibility enhancement mode, visibility that can clearly see the display target image displayed on the display device 30 is more important than the image quality in an environment where strong external light such as sunlight is irradiated. .

  For this reason, in the visibility improvement mode, the image correction unit 18 performs edge enhancement with a higher edge enhancement degree than the normal edge enhancement degree in addition to the expansion of the display target image as an image correction process. Visibility is improved by displaying a bright, vivid and clear display target image in the device 30.

  In addition, for example, the degree of contour enhancement when performing contour enhancement in the image correction unit 18 can be set in the control unit 13 according to the operation of the operation unit 14 and supplied to the image correction unit 18.

  [Light emission amount calculation processing]

  FIG. 9 is a flowchart for explaining the light emission amount calculation processing performed by the light emission amount calculation unit 19 of FIG.

  In step S41, the light emission amount calculation unit 19 selects a light emission magnification characteristic corresponding to the display mode according to the latest display mode from the control unit 13, and the process proceeds to step S42.

  That is, when the display mode is the power saving mode, the light emission amount calculation unit 19 selects the light emission magnification characteristic # 1 (FIG. 4A) as the light emission magnification characteristic corresponding to the display mode, and the display mode improves the visibility. In the case of the mode, the light emission magnification characteristic # 2 (FIG. 4B) is selected as the light emission magnification characteristic corresponding to the display mode.

  In step S42, the light emission amount calculation unit 19 sets the light emission magnification with respect to the corrected maximum pixel value Pm ′ according to the corrected maximum pixel value Pm ′ from the maximum pixel value correction unit 17 in accordance with the light emission magnification characteristic corresponding to the display mode. The calculation proceeds to step S43.

  In step S43, the light emission amount calculation unit 19 calculates the light emission amount of the light source 32 used for displaying the frame of interest by multiplying the latest reference light emission amount from the control unit 13 with the light emission magnification, and the light emission amount. Is supplied to the light source driving unit 31.

  Thereafter, the process returns from step S43 to step S41, and the same process is repeated thereafter.

  [Expansion of pixel values and gradation correction as image correction processing]

  FIG. 10 is a diagram for explaining pixel value expansion and gradation correction performed by the image correction unit 18 of FIG. 1 as image correction processing.

  In the pixel value expansion performed by the image correction unit 18 as the image correction process, as described with reference to FIG. 5, the pixel value (not the maximum pixel value Pm but the corrected maximum pixel value Pm ′ smaller than the maximum pixel value Pm) The input pixel value) is expanded at a higher expansion rate MAX / Pm ′ than in the normal expansion. Therefore, the power consumption is reduced as compared with the normal expansion, and the visibility is improved as compared with the normal expansion. Can also be improved.

  However, if the pixel value of the display target image is simply expanded at a higher expansion rate MAX / Pm ′ than in the normal expansion, the expanded pixel value (output pixel value) is the maximum value that can be taken as the pixel value. Since it is limited to the value MAX, the pixel values from the corrected maximum pixel value Pm ′ to the maximum pixel value Pm among the pixel values of the display target image are all saturated after expansion, that is, the maximum value MAX is displayed. A display target image (hereinafter also referred to as a display image) displayed on the device 30 has a so-called whitened portion.

  Therefore, in order to prevent such whitening from occurring, the image correction unit 18 can perform gradation correction in addition to pixel value expansion as image correction processing (image conversion processing among them). .

  Here, the pixel values before the display target image expansion and gradation correction are performed are referred to as input pixel values, and the pixel values after the display target image expansion and gradation correction are performed are referred to as output pixel values. Then, the image correction process for performing the expansion of the display target image and the gradation correction can be referred to as an image conversion process for converting the input pixel value into the output pixel value.

  FIG. 10 shows decompression gradation conversion input / output characteristics that are input / output characteristics of image conversion processing for performing expansion and gradation correction of a display target image.

  FIG. 10 also shows the MAX / Pm ′ double expansion input / output characteristics, the normal expansion input / output characteristics, and the 1 × expansion input / output characteristics shown in FIG.

  According to the expansion gradation conversion input / output characteristics, the pixel value of the display target image is expanded at the expansion rate MAX / Pm ′, and the pixel value from the corrected maximum pixel value Pm ′ to the maximum pixel value Pm is saturated by the expansion. Gradation correction to suppress the image is performed.

  Therefore, it is possible to prevent the display image from being whitened (the display target image is broken) due to the saturation of the pixel value from the corrected maximum pixel value Pm ′ to the maximum pixel value Pm of the display target image. it can.

  As a result, it is possible to display a display image having the same image quality as when the display target image is displayed without performing the image correction process and the light amount calculation process.

  The image correction unit 18 performs image conversion processing according to the expansion gradation conversion input / output characteristics, that is, expansion of the pixel value of the display target image at the expansion ratio MAX / Pm ′, and the maximum corrected pixel value by the expansion. When the gradation correction for suppressing the saturation of the pixel values from Pm ′ to the maximum pixel value Pm is performed as the image correction process, the maximum pixel value correction unit 17 determines the maximum pixel in addition to the corrected maximum pixel value Pm ′. The maximum pixel value Pm from the value detection unit 16 (or a correction amount that is information that can be used together with the corrected maximum pixel value to obtain the maximum pixel value) is supplied to the image correction unit 18.

  In the image correction unit 18, the extended gradation conversion input / output characteristics are obtained using the corrected maximum pixel value Pm ′ and the maximum pixel value Pm from the maximum pixel value correction unit 17. The image conversion process according to the above is performed.

  For example, a quadratic function can be used as the extended gradation conversion input / output characteristic.

  That is, in a two-dimensional plane with the input pixel value as the x-axis and the output pixel value as the y-axis, the point (Pm, MAX) is the vertex and is in contact with the straight line representing the MAX / Pm′-fold expansion input / output characteristics An upward convex quadratic function can be employed as the extended gradation conversion input / output characteristic.

  It should be noted that the expansion / conversion conversion input / output characteristics in which expansion and gradation correction are performed are the same as the MAX / Pm'-fold expansion input / output characteristics in comparison with the MAX / Pm'-fold expansion input / output characteristics in which only expansion is performed. Although it is a characteristic that suppresses saturation of the pixel value from the corrected maximum pixel value Pm ′ to the maximum pixel value Pm due to the extension according to the extension, the image to be displayed is compared with the normal extension according to the normal extension input / output characteristics. The so-called lifting characteristic is obtained.

  As described above, when the image correction unit 18 (FIG. 1) performs the image conversion process according to the expansion gradation conversion input / output characteristics, the power consumption is reduced compared to the case of normal expansion while preventing whiteout. While reducing, visibility can be improved rather than the case of normal expansion | extension.

  [Image correction processing]

  FIG. 11 is a flowchart illustrating an image correction process including an image conversion process according to the decompression gradation conversion input / output characteristics.

  In step S51, the image correction unit 18 selects the expansion rate characteristic corresponding to the display mode in accordance with the latest display mode from the control unit 13 in the same manner as in step S31 of FIG. Proceed to S52.

  In step S52, the image correction unit 18 follows the expansion rate characteristic corresponding to the display mode in accordance with the corrected maximum pixel value Pm ′ from the maximum pixel value correction unit 17 in the same manner as in step S32 of FIG. The expansion rate for the corrected maximum pixel value Pm ′ is calculated, and the process proceeds to step S53.

  In step S53, the image correction unit 18 performs expansion gradation conversion input / output characteristics, that is, expansion at an expansion rate with respect to the corrected maximum pixel value Pm ′ and gradation correction that suppresses saturation of the pixel value due to the expansion. The input / output characteristics of the image conversion process are calculated based on the corrected maximum pixel value Pm ′ and the maximum pixel value Pm from the maximum pixel value correcting unit 17, and the process proceeds to step S54.

  In step S54, the image correction unit 18 performs image conversion processing in which pixel value expansion and gradation correction of the frame of interest are performed according to the expansion gradation conversion input / output characteristics.

  Thereafter, the process proceeds from step S54 to step S55, and the image correction unit 18 performs a process of performing the edge enhancement of the frame of interest after the image conversion process at the edge enhancement degree corresponding to the display mode.

  Then, the image correction unit 18 supplies the display target image after the outline enhancement to the display panel 33, the process returns from step S55 to step S51, and the same process is repeated thereafter.

  [Display mode setting]

  FIG. 12 is a flowchart for explaining display mode setting processing performed by the display mode setting unit 41 of FIG.

  In step S61, the display mode setting unit 41 determines whether the display mode setting mode is set to the manual mode or the automatic mode described in FIG.

  If it is determined in step S61 that the display mode setting mode is the manual mode, the process proceeds to step S62, and the display mode setting unit 41 causes the operation unit 14 to change the display mode to the power saving mode or the visibility enhancement mode. It is determined whether or not the operation is performed.

  Here, the operation of the operation unit 14 in which the display mode is the power saving mode is also referred to as a power saving mode operation, and the operation of the operation unit 14 in which the display mode is the visibility improvement mode is also referred to as a visibility improvement mode operation.

  If it is determined in step S62 that neither the power saving mode operation nor the visibility improvement mode operation is performed, the process returns to step S61.

  If it is determined in step S62 that the power saving mode operation or the visibility improvement mode operation has been performed, the process proceeds to step S63 or S64, and the display mode setting unit 41 operates the display mode. The setting is performed according to the operation of the unit 14, and the process returns to step S61.

  That is, if it is determined in step S62 that the power saving mode operation has been performed, the process proceeds to step S63, and the display mode setting unit 41 sets the display mode to the power saving mode.

  If it is determined in step S62 that the visibility enhancement mode operation has been performed, the process proceeds to step S64, and the display order setting unit 41 sets the display mode to the visibility enhancement mode.

  On the other hand, when it is determined in step S61 that the display mode setting mode is the automatic mode, the process proceeds to step S65, and the display mode setting unit 41 receives the external light represented by the illuminance data from the A / D conversion unit 12. Is determined to be greater than or equal to a mode switching threshold value for switching the display mode.

  Here, the mode switching threshold value is stored in advance in the memory 13B of the control unit 13, for example.

  If it is determined in step S65 that the illuminance of outside light is not equal to or greater than the mode switching threshold, that is, the environment in which the display target image is displayed on the display device 30 is an environment that is not so bright, such as indoors. If there is, the process proceeds to step S63, the display mode setting unit 41 sets the display mode to the power saving mode, and the process returns to step S61.

  Further, when it is determined in step S65 that the illuminance of outside light is equal to or higher than the mode switching threshold, that is, the environment in which the display target image is displayed on the display device 30 is, for example, sunny sunny or the like. If the environment is bright, the process proceeds to step S64, the display mode setting unit 41 sets the display mode to the visibility enhancement mode, and the process returns to step S61.

  As described above, when the display mode setting mode is the manual mode, the user can select the display mode by operating the operation unit 14.

  In addition, when the display mode setting mode is the automatic mode, the power saving mode is set in the environment where there is no problem with visibility according to the illuminance of outside light, and the brightness is not so bright. In the environment, a visibility enhancement mode is set.

  As a result, power consumption can be reduced in an environment where there is no problem in visibility and the brightness is not so bright, and visibility can be improved in a bright environment where visibility is deteriorated.

  [Correction amount setting]

  FIG. 13 is a flowchart for explaining the correction amount setting process performed by the correction amount setting unit 42 of FIG.

  In step S71, the correction amount setting unit 42 determines whether the correction amount setting mode is set to the manual mode, the fixed mode, or the variable mode described in FIG.

  If it is determined in step S71 that the correction amount setting mode is a manual mode in which the correction amount is set according to the operation signal from the operation unit 14, the process proceeds to step S72, and the correction amount setting unit 42 The correction amount is set according to the operation of 14, and the process returns to step S71.

  If it is determined in step S71 that the correction amount setting mode is a fixed mode for setting a correction amount of a fixed value according to the display mode, the process proceeds to step S73, and the correction amount setting unit 42 It is determined whether the setting mode is set to the manual mode or the automatic mode.

  If it is determined in step S73 that the display mode setting mode is the automatic mode, the process proceeds to step S74, and the correction amount setting unit 42 corrects the fixed value according to the display mode, as will be described later. The amount is set, and the process returns to step S71.

  If it is determined in step S73 that the display mode setting mode is the manual mode, the process proceeds to step S75, and the correction amount setting unit 42 determines that the display mode is the power saving mode and the visibility improvement. Determine which of the modes is set.

  If it is determined in step S75 that the display mode is the power saving mode, the process proceeds to step S76, and the correction amount setting unit 42 sets the correction amount to a fixed value for the power saving mode, as will be described later. And the process returns to step S71.

  If it is determined in step S75 that the display mode is the visibility enhancement mode, the process proceeds to step S77, and the correction amount setting unit 42 sets the correction amount to the visibility enhancement mode as described later. The process returns to step S71.

  On the other hand, if it is determined in step S71 that the correction amount setting mode is a variable mode in which the correction amount is set according to the illuminance of external light, the process proceeds to step S78, and the correction amount setting unit 42 sets the display mode setting. It is determined whether the mode is set to manual mode or automatic mode.

  If it is determined in step S78 that the display mode setting mode is the automatic mode, the process proceeds to step S79, and the correction amount setting unit 42 corrects the relationship between the illuminance and the correction amount, as will be described later. A correction amount for the illuminance represented by the illuminance data from the A / D converter 12 is set according to the correction amount characteristic for the automatic mode, which is the amount characteristic and the correction amount characteristic used when the display mode setting mode is the automatic mode. Then, the process returns to step S71.

  If it is determined in step S78 that the display mode setting mode is the manual mode, the process proceeds to step S80, and the correction amount setting unit 42 determines that the display mode is the power saving mode and the visibility is improved. Determine which of the modes is set.

  If it is determined in step S80 that the display mode is the power saving mode, the process proceeds to step S81, and the correction amount setting unit 42 is used when the display mode is the power saving mode, as will be described later. The correction amount for the illuminance represented by the illuminance data from the A / D converter 12 is set according to the correction amount characteristic for the power saving mode, which is the correction amount characteristic, and the process returns to step S71.

  If it is determined in step S80 that the display mode is the visibility enhancement mode, the process proceeds to step S82, and the correction amount setting unit 42 determines that the display mode is the visibility enhancement mode, as will be described later. The correction amount for the illuminance represented by the illuminance data from the A / D conversion unit 12 is set in accordance with the correction amount characteristic for the visibility enhancement mode, which is a correction amount characteristic used in some cases, and the process returns to step S71.

  FIG. 14 is a diagram illustrating a correction amount characteristic representing a relationship between the illuminance represented by the illuminance data supplied from the A / D conversion unit 12 to the correction amount setting unit 42 and the correction amount set by the correction amount setting unit 42. .

  14A shows the correction amount characteristic # 1 when the correction amount setting unit 42 sets the correction amount according to the display mode in step S74 of FIG.

According to the correction amount characteristic # 1, when the illuminance is less than the mode switching threshold, and the display mode setting mode is set to the automatic mode, and the display mode is set to the power saving mode, A fixed value V ₁ for the power saving mode, which is a predetermined small value, is set as the correction amount.

Further, according to the correction amount characteristic # 1, when the illuminance is equal to or higher than the mode switching threshold value, and the display mode setting mode is set to the automatic mode, the display mode is set to the visibility enhancement mode. Is set, the fixed value V ₂ for the visibility enhancement mode, which is larger than the fixed value V ₁ for the power saving mode, is set as the correction amount.

  As described above, in the power saving mode, a small value is set as the correction amount, and in the visibility improvement mode, a larger value is set as the correction amount than in the power saving mode.

  When the correction amount is large, the corrected maximum pixel value Pm ′ becomes small, and the expansion rate for the corrected maximum pixel value Pm ′ calculated according to the expansion rate characteristic (FIG. 4) becomes large.

  Therefore, in the visibility improvement mode, the display target image is expanded at a larger expansion rate than in the power saving mode.

  As a result, the display target image (display image) displayed on the display device 30 becomes a brighter image, and visibility can be improved.

FIG. 14B shows the correction amount characteristic # 2 when the correction amount setting unit 42 sets the correction amount to the fixed value V ₁ for the power saving mode in step S76 of FIG.

According to the correction amount characteristic # 2, the amount of correction, irrespective of the illuminance it is set to a fixed value V ₁ of the power-saving mode.

Figure 14C, the correction amount setting unit 42, at step S77 of FIG. 13 shows the correction amount characteristic # 3 when the correction amount is set to a fixed value V ₂ for improving visibility mode.

According to the correction amount characteristic # 3, the correction amount, regardless of the illuminance it is set to a fixed value V ₂ for improving visibility mode.

  FIG. 14D shows the correction amount characteristic # 4 as the correction amount characteristic for the automatic mode used by the correction amount setting unit 42 for setting the correction amount in step S79 of FIG.

Correction characteristic # 4, illumination, when it is less than the mode switching threshold, with increasing intensity, from a fixed value V _1, at larger than the fixed value V _1, the shorter than the fixed value V ₂ V ₀ 'has become a monotonically increasing characteristic up, illumination, when it is more than the mode switching threshold, with increasing intensity, the value V _0' in larger than small value V than the fixed value V _{2 3} ', and is monotonically increasing characteristic up to a fixed value V _3.

  FIG. 14E shows the correction amount characteristic # 5 as the correction amount characteristic for the power saving mode used by the correction amount setting unit 42 for setting the correction amount in step S81 of FIG.

The correction amount characteristic # 5 is a characteristic that monotonously increases from the fixed value V _{1 with} respect to an increase in illuminance.

  Therefore, according to the correction amount characteristic # 5, a larger amount of correction amount is set as the illuminance increases.

In the correction amount characteristic # 5, the correction amount when the illuminance is equal to the mode switching threshold is the value V ₀ ′ described in the correction amount characteristic # 4 of FIG. 14D.

  FIG. 14F shows the correction amount characteristic # 6 as the correction amount characteristic for the visibility enhancement mode used by the correction amount setting unit 42 for setting the correction amount in step S82 of FIG.

The correction amount characteristic # 6 is a characteristic that monotonously increases up to a fixed value V _{3 with} respect to an increase in illuminance.

  Therefore, according to the correction amount characteristic # 6, the larger the illuminance, the larger the correction amount is set.

In the correction amount characteristic # 6, the correction amount when the illuminance is equal to the mode switching threshold is the value V ₃ ′ described in the correction amount characteristic # 4 of FIG. 14D.

  Further, the correction amount characteristic # 4 for the automatic mode in FIG. 14D matches the correction amount characteristic # 5 for the power saving mode in FIG. 14E for the illuminance below the mode switching threshold, and This is consistent with the correction amount characteristic # 6 for the visibility enhancement mode.

  [Color signal expansion ratio]

  FIG. 15 is a diagram illustrating a relationship among the correction amount setting mode, the display mode setting mode, and the display mode, and the correction amount, the light emission magnification, the contour enhancement degree, and the color signal expansion rate.

  Here, when the pixel value of the display target image has a plurality of signals as components, a corrected maximum pixel value is calculated separately for each of the plurality of signals, and an image is displayed according to the corrected maximum pixel value. Correction processing can be performed.

  That is, when the pixel value of the display target image includes, for example, a luminance signal and a color signal as a plurality of components, the luminance signal is subjected to image correction processing for the luminance signal and the color reproducibility is maintained. Separately (independently), image correction processing can be performed on the color signal.

  However, for the color signal, only the expansion using the expansion rate calculated for the luminance signal can be performed as the color signal image correction processing.

  FIG. 15 illustrates a correction amount setting mode, a display mode setting mode, a display mode, a correction amount, a light emission magnification, and contour emphasis when the pixel value of the display target image has a luminance signal and a color signal as components. The relationship between the degree of color and the expansion rate of the color signal is shown.

  When the correction amount setting mode is set to the fixed mode, the display mode setting mode is set to the automatic mode, and the display mode is set to the power saving mode, the luminance signal correction amount is calculated according to the correction amount characteristic # 1 of FIG. 14A. Is done. As the luminance signal expansion rate, the expansion rate with respect to the corrected maximum pixel value (luminance signal) calculated from the correction amount of the luminance signal is calculated according to the expansion rate characteristic # 1 (FIG. 4).

  Further, the light emission magnification is calculated according to the light emission magnification characteristic # 1 (FIG. 4), and the contour enhancement degree is set to “weak” or “medium” (normal outline enhancement degree).

  Further, the luminance signal expansion rate is set as the color signal expansion rate, and the image correction unit 18 performs image correction processing on each of the luminance signal and the color signal. In other words, luminance signal and color signal expansion, luminance signal gradation correction, and contour enhancement are performed.

  When the correction amount setting mode is set to the fixed mode, the display mode setting mode is set to the automatic mode, and the display mode is set to the visibility enhancement mode, the correction amount of the luminance signal is in accordance with the correction amount characteristic # 1 of FIG. 14A. Calculated. Then, as the expansion rate of the luminance signal, the expansion rate with respect to the corrected maximum pixel value calculated from the correction amount of the luminance signal is calculated according to the expansion rate characteristic # 2 (FIG. 4).

  The light emission magnification is calculated according to the light emission magnification characteristic # 2 (FIG. 4), and the contour enhancement degree is “strong”.

  Further, as the expansion rate of the color signal, a value obtained by adding a predetermined margin set in advance to the expansion rate of the luminance signal is set. Then, image correction processing is performed.

  When the correction amount setting mode is set to the fixed mode, the display mode setting mode is set to the manual mode, and the display mode is set to the power saving mode, the luminance signal correction amount is calculated according to the correction amount characteristic # 2 of FIG. 14B. Is done. As the luminance signal expansion rate, the expansion rate with respect to the corrected maximum pixel value calculated from the correction amount of the luminance signal is calculated according to the expansion rate characteristic # 1 (FIG. 4).

  Further, the light emission magnification is calculated according to the light emission magnification characteristic # 1 (FIG. 4), and the contour enhancement degree is set to “weak” or “medium”.

  Further, the luminance signal expansion rate is set as the color signal expansion rate, and the image correction unit 18 performs image correction processing on each of the luminance signal and the color signal.

  When the correction amount setting mode is set to the fixed mode, the display mode setting mode is set to the manual mode, and the display mode is set to the visibility enhancement mode, the correction amount of the luminance signal is in accordance with the correction amount characteristic # 3 of FIG. 14C. Calculated. Then, as the expansion rate of the luminance signal, the expansion rate with respect to the corrected maximum pixel value calculated from the correction amount of the luminance signal is calculated according to the expansion rate characteristic # 2 (FIG. 4).

  The light emission magnification is calculated according to the light emission magnification characteristic # 2 (FIG. 4), and the contour enhancement degree is “strong”.

  Further, as the color signal expansion rate, a value obtained by adding a predetermined margin to the luminance signal expansion rate is set, and the image correction unit 18 performs image correction processing on each of the luminance signal and the color signal.

  When the correction amount setting mode is set to the variable mode, the display mode setting mode is set to the automatic mode, and the display mode is set to the power saving mode, the luminance signal correction amount is calculated according to the correction amount characteristic # 4 of FIG. 14D. Is done. As the luminance signal expansion rate, the expansion rate with respect to the corrected maximum pixel value (luminance signal) calculated from the correction amount of the luminance signal is calculated according to the expansion rate characteristic # 1 (FIG. 4).

  Further, the light emission magnification is calculated according to the light emission magnification characteristic # 1 (FIG. 4), and the contour enhancement degree is set to “weak” or “medium”.

  Further, the luminance signal expansion rate is set as the color signal expansion rate, and the image correction unit 18 performs image correction processing on each of the luminance signal and the color signal.

  When the correction amount setting mode is set to the variable mode, the display mode setting mode is set to the automatic mode, and the display mode is set to the visibility enhancement mode, the correction amount of the luminance signal is in accordance with the correction amount characteristic # 4 of FIG. 14D. Calculated. Then, as the expansion rate of the luminance signal, the expansion rate with respect to the corrected maximum pixel value calculated from the correction amount of the luminance signal is calculated according to the expansion rate characteristic # 2 (FIG. 4).

  The light emission magnification is calculated according to the light emission magnification characteristic # 2 (FIG. 4), and the contour enhancement degree is “strong”.

  Further, as the color signal expansion rate, a value obtained by adding a predetermined margin to the luminance signal expansion rate is set, and the image correction unit 18 performs image correction processing on each of the luminance signal and the color signal.

  When the correction amount setting mode is set to the variable mode, the display mode setting mode is set to the manual mode, and the display mode is set to the power saving mode, the correction amount of the luminance signal is calculated according to the correction amount characteristic # 5 of FIG. 14E. Is done. As the luminance signal expansion rate, the expansion rate with respect to the corrected maximum pixel value calculated from the correction amount of the luminance signal is calculated according to the expansion rate characteristic # 1 (FIG. 4).

  Further, the light emission magnification is calculated according to the light emission magnification characteristic # 1 (FIG. 4), and the contour enhancement degree is set to “weak” or “medium”.

  Further, the luminance signal expansion rate is set as the color signal expansion rate, and the image correction unit 18 performs image correction processing on each of the luminance signal and the color signal.

  When the correction amount setting mode is set to the variable mode, the display mode setting mode is set to the manual mode, and the display mode is set to the visibility improving mode, the luminance signal correction amount is determined according to the correction amount characteristic # 6 of FIG. 14F. Calculated. Then, as the expansion rate of the luminance signal, the expansion rate with respect to the corrected maximum pixel value calculated from the correction amount of the luminance signal is calculated according to the expansion rate characteristic # 2 (FIG. 4).

  The light emission magnification is calculated according to the light emission magnification characteristic # 2 (FIG. 4), and the contour enhancement degree is “strong”.

  Further, a value obtained by adding a predetermined margin to the luminance signal expansion rate is set as the color signal expansion rate, and the image correction unit 18 performs image correction processing on each of the luminance signal and the color signal.

  Note that the image correction unit 18 performs image correction processing when the display mode is the visibility enhancement mode, in addition to the display device 30 that displays an image using light from the light source 32, for example, organic EL (Electro Luminescence). The present invention can also be applied to a self-luminous display device such as a display device using the above.

  [Description of Computer to which the Present Invention is Applied]

  Next, of the processes performed by the display control apparatus 10 described above, the processes performed by the histogram generation unit 15 or the light emission amount calculation unit 19 in addition to the processes performed by the control unit 13 can be performed by hardware or software. Can also be performed.

  When a series of processing performed by the control unit 13 or the histogram generation unit 15 or the light emission amount calculation unit 19 is performed by software, a program constituting the software is installed in a microcomputer or the like.

  Therefore, FIG. 16 shows a configuration example of an embodiment of a computer in which a program for executing the series of processes described above is installed.

  The program can be recorded in advance on a hard disk 105 or a ROM 103 as a recording medium built in the computer.

  Alternatively, the program can be stored (recorded) in the removable recording medium 111. Such a removable recording medium 111 can be provided as so-called package software. Here, examples of the removable recording medium 111 include a flexible disk, a CD-ROM (Compact Disc Read Only Memory), an MO (Magneto Optical) disk, a DVD (Digital Versatile Disc), a magnetic disk, and a semiconductor memory.

  In addition to installing the program from the removable recording medium 111 as described above, the program can be downloaded to the computer via a communication network or a broadcast network, and can be installed in the built-in hard disk 105. That is, for example, the program is wirelessly transferred from a download site to a computer via a digital satellite broadcasting artificial satellite, or wired to a computer via a network such as a LAN (Local Area Network) or the Internet. be able to.

  The computer incorporates a CPU (Central Processing Unit) 102, and an input / output interface 110 is connected to the CPU 102 via a bus 101.

  The CPU 102 executes a program stored in a ROM (Read Only Memory) 103 according to a command input by the user by operating the input unit 107 or the like via the input / output interface 110. . Alternatively, the CPU 102 loads a program stored in the hard disk 105 to a RAM (Random Access Memory) 104 and executes it.

  Thus, the CPU 102 performs processing according to the above-described flowchart or processing performed by the configuration of the above-described block diagram. Then, the CPU 102 outputs the processing result as necessary, for example, via the input / output interface 110, from the output unit 106, transmitted from the communication unit 108, and further recorded in the hard disk 105.

  The input unit 107 includes a keyboard, a mouse, a microphone, and the like. The output unit 106 includes an LCD (Liquid Crystal Display), a speaker, and the like.

  Here, in the present specification, the processing performed by the computer according to the program does not necessarily have to be performed in time series in the order described as the flowchart. That is, the processing performed by the computer according to the program includes processing executed in parallel or individually (for example, parallel processing or object processing).

  Further, the program may be processed by one computer (processor) or may be distributedly processed by a plurality of computers. Furthermore, the program may be transferred to a remote computer and executed.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 10 Display control apparatus, 11 Illuminance sensor, 12 A / D conversion part, 13 Control part, 13A CPU, 13B Memory, 14 Operation part, 15 Histogram generation part, 16 Maximum pixel value detection part, 17 Maximum pixel value correction part, 18 Image correction unit, 19 Light emission amount calculation unit, 30 Display device, 31 Light source drive unit, 32 Light source, 33 Display panel, 41 Display mode setting unit, 42 Correction amount setting unit, 43 Reference light emission amount setting unit, 101 Bus, 102 CPU , 103 ROM, 104 RAM, 105 hard disk, 106 output unit, 107 input unit, 108 communication unit, 109 drive, 110 input / output interface, 111 removable recording medium

Claims (9)

A maximum pixel value detecting means for detecting a maximum pixel value that is a maximum pixel value from a pixel value of a display target image that is an image to be displayed on a display device that displays an image using light from a light source;
Correction amount setting means for setting a correction amount for correcting the maximum pixel value;
Maximum pixel value correcting means for correcting the maximum pixel value according to the correction amount and calculating a corrected maximum pixel value of a value smaller than the maximum pixel value;
As a display mode for displaying an image on the display device, a power saving mode for reducing power consumption, or a display mode setting means for setting a visibility improvement mode for improving the visibility of an image displayed on the display device;
As image correction processing for correcting the display target image, image correction means for performing processing for expanding the pixel value of the display target image according to the corrected maximum pixel value;
A light emission amount calculating unit that performs a process of calculating the light emission amount according to the corrected maximum pixel value as a light emission amount calculation process for calculating a light emission amount of light emitted from the light source;
When the display mode is the power saving mode,
The light emission amount calculating means calculates, as the light emission amount of the light source, a light emission amount equal to or less than a reference light emission amount that is a reference light emission amount set in advance according to the corrected maximum pixel value.
When the display mode is the visibility improvement mode,
The light emission amount calculating means calculates the reference light emission amount or a light emission amount larger than the reference light emission amount as the light emission amount of the light source,
The display control device, wherein the image correction means also performs gradation correction for suppressing saturation of pixel values from the corrected maximum pixel value to the maximum pixel value due to the expansion as the image correction processing. The image correction means is an expansion rate characteristic that is a characteristic of an expansion rate that monotonously decreases with respect to an increase in the corrected maximum pixel value, and sets a value larger than 1 to a maximum value and 1 time. In accordance with the minimum expansion rate characteristic, the expansion rate for the corrected maximum pixel value is calculated, and the pixel value of the display target image is expanded at the expansion rate,
The light emission amount calculating means is configured to increase the correction maximum pixel value according to a light emission magnification characteristic that is a light emission magnification characteristic that represents a ratio of the light emission amount to the reference light emission amount, which monotonically increases with an increase in the corrected maximum pixel value. By calculating the light emission magnification and multiplying the light emission magnification by the reference light emission amount, the light emission amount of the light source is calculated,
When the display mode is the power saving mode,
The light emission amount calculating means sets the reciprocal of the maximum value of the expansion rate to a minimum value and follows the first light emission magnification characteristic that is the light emission magnification characteristic having a maximum value of 1 ×, and Calculate the flash magnification,
When the display mode is the visibility improvement mode,
The display control apparatus according to claim 1, wherein the light emission amount calculation unit calculates the light emission magnification with respect to the corrected maximum pixel value according to a second light emission magnification characteristic that is the light emission magnification characteristic having a minimum value of 1 ×. Further comprising illuminance detection means for detecting the illuminance of outside light,
The display control apparatus according to claim 2, wherein the display mode setting unit sets the display mode according to the illuminance. The display control apparatus according to claim 3, wherein the correction amount setting unit sets the correction amount according to the display mode. Further comprising illuminance detection means for detecting the illuminance of outside light,
The display control apparatus according to claim 2, wherein the correction amount setting unit sets the correction amount according to the illuminance. The image correcting means includes
Contour enhancement that emphasizes the contour of the display target image is also performed as the image correction processing,
3. When the display mode is the visibility enhancement mode, an edge enhancement degree, which is a degree of edge enhancement by the edge enhancement, is made stronger than when the display mode is the power saving mode. The display control apparatus described. The display control apparatus according to claim 2, wherein the display mode setting unit sets the display mode according to a user operation. A display control device that controls display of an image by a display device that displays an image using light from a light source,
A maximum pixel value detecting step for detecting a maximum pixel value which is a maximum pixel value from a pixel value of a display target image which is an image to be displayed on the display device;
A correction amount setting step for setting a correction amount for correcting the maximum pixel value;
A maximum pixel value correcting step for correcting the maximum pixel value according to the correction amount and calculating a corrected maximum pixel value having a value smaller than the maximum pixel value;
As a display mode for displaying an image on the display device, a display mode setting step for setting a power saving mode for reducing power consumption or a visibility improving mode for improving the visibility of an image displayed on the display device;
As an image correction process for correcting the display target image, an image correction step for performing a process of expanding a pixel value of the display target image according to the corrected maximum pixel value;
A light emission amount calculating step of calculating a light emission amount of light to be emitted from the light source, and performing a process of calculating the light emission amount according to the corrected maximum pixel value,
When the display mode is the power saving mode,
In the light emission amount calculating step, according to the corrected maximum pixel value, a light emission amount equal to or less than a reference light emission amount that is a reference light emission amount set in advance is calculated as the light emission amount of the light source,
When the display mode is the visibility improvement mode,
In the light emission amount calculating step, the reference light emission amount or a light emission amount larger than the reference light emission amount is calculated as the light emission amount of the light source,
In the image correction step, gradation correction that suppresses saturation of pixel values from the corrected maximum pixel value to the maximum pixel value due to the expansion is also performed as the image correction process. A maximum pixel value detecting means for detecting a maximum pixel value that is a maximum pixel value from a pixel value of a display target image that is an image to be displayed on a display device that displays an image using light from a light source;
Correction amount setting means for setting a correction amount for correcting the maximum pixel value;
Maximum pixel value correcting means for correcting the maximum pixel value according to the correction amount and calculating a corrected maximum pixel value of a value smaller than the maximum pixel value;
As a display mode for displaying an image on the display device, a power saving mode for reducing power consumption, or a display mode setting means for setting a visibility improvement mode for improving the visibility of an image displayed on the display device;
As image correction processing for correcting the display target image, image correction means for performing processing for expanding the pixel value of the display target image according to the corrected maximum pixel value;
As a light emission amount calculation process for calculating a light emission amount of light to be emitted from the light source, a light emission amount calculation unit that performs a process of calculating the light emission amount according to the corrected maximum pixel value is used for causing a computer to function. Program,
When the display mode is the power saving mode,
The light emission amount calculating means calculates, as the light emission amount of the light source, a light emission amount equal to or less than a reference light emission amount that is a preset reference light emission amount according to the corrected maximum pixel value
When the display mode is the visibility improvement mode,
The light emission amount calculating means calculates the reference light emission amount or a light emission amount larger than the reference light emission amount as the light emission amount of the light source,
The image correction means is a program that performs gradation correction for suppressing saturation of pixel values from the corrected maximum pixel value to the maximum pixel value by the expansion as the image correction processing.

Images