Display device and control method

Abstract

To provide a technique for further improvement in a display device.SOLUTION: In a display device 1, a display part 10 has a display area for displaying a displayed image, and a peripheral area surrounding the display area. A control circuit 20 acquires an illuminance from an illuminance sensor 22 for detecting the illuminance of incident light, and controls the display part 10. The display area includes a first edge area which is an area positioned near the peripheral area. The control circuit 20 derives a brightness ratio which is a ratio between the brightness of the first edge area and the brightness of the peripheral area, based on the illuminance and image data of the displayed image. When the brightness ratio is larger than a brightness ratio threshold value which is a predetermined value, the control circuit 20 controls the display part 10 such that the brightness ratio becomes equal to or less than the brightness ratio threshold value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a display device and a control method. [Background technology]

[0002] Image display devices are known that adaptively control video signal processing and display brightness (see, for example, Patent Document 1). The image display device detects changes in ambient illuminance and detects video characteristics such as the average value of the brightness of the input video. When the illuminance changes rapidly and significantly, the image display device calculates adaptive target characteristics using a predetermined LPF calculation for the detected illuminance change. Using the adaptive target characteristics as target values, the image display device adaptively controls video signal processing and display brightness while considering the video characteristics of the input video. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-285064 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Further improvements are needed in display devices. [Means for solving the problem]

[0005] To solve the above problems, a display device according to one aspect of the present disclosure includes a display unit having a display area for displaying a display image and a peripheral area surrounding the display area, and a control circuit that acquires illuminance from an illuminance sensor for detecting the illuminance of incident light and controls the display unit. The display area includes a first end area which is an area located near the peripheral area. The control circuit derives a luminance ratio, which is the ratio of the luminance of the first end area to the luminance of the peripheral area, based on the illuminance and image data of the display image, and controls the display unit so that the luminance ratio becomes less than or equal to the luminance ratio threshold, which is a predetermined value, if the luminance ratio is greater than a luminance ratio threshold.

[0006] Another aspect of the present disclosure is a control method. This method is a control method for a display device, comprising a display unit having a display area for displaying a display image and a peripheral area surrounding the display area, wherein the display area includes a first end area which is a region located near the peripheral area, and comprises the steps of: acquiring illuminance from an illuminance sensor for detecting the illuminance of incident light; deriving a luminance ratio, which is the ratio of the luminance of the first end area to the luminance of the peripheral area, based on the illuminance; and, if the luminance ratio is greater than a predetermined luminance ratio threshold, controlling the display unit so that the luminance ratio becomes less than or equal to the luminance ratio threshold. [Effects of the Invention]

[0007] Further improvements can be achieved through the above-described method. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the configuration of the display device according to the embodiment. [Figure 2] This is a plan view of the display unit shown in Figure 1. [Figure 3] This is a longitudinal cross-sectional view of the display unit in Figure 2, along the line III-III. [Figure 4] This figure shows the brightness at each position of the display unit when the illuminance of ambient light incident on the display unit is relatively high. [Figure 5] This figure shows the brightness of each position on the display unit before image correction when the illuminance of ambient light incident on the display unit in Figure 3 is relatively low. [Figure 6] This is a diagram showing the luminance of each position on the display unit after image correction when the illuminance of external light incident on the display unit in FIG. 3 is relatively low. [Figure 7] This is a diagram for explaining the image luminance reduction process of the central image. [Figure 8] This is a diagram for explaining the correction value in the display image of FIG. 7. [Figure 9] This is a diagram for explaining the correction value in another display image. [Figure 10] This is a diagram for explaining the image luminance reduction process of the entire image. [Figure 11] This is a diagram showing the luminance before correction of each position on the display unit when the illuminance of external light incident on the display unit in FIG. 1 is relatively low and the second end region is black-displayed. [Figure 12] This is a diagram showing the luminance after correction of each position on the display unit when the illuminance of external light incident on the display unit in FIG. 1 is relatively low and the second end region is black-displayed. [Figure 13] This is a diagram for explaining the correction value in the light intensity reduction process. [Figure 14] This is a diagram for explaining the correction value in another display image. [Figure 15] This is a flowchart showing the processing of the control circuit in FIG. 1.

Mode for Carrying Out the Invention

[0009] (Knowledge on which the present disclosure is based) Before specifically explaining the embodiments, the underlying knowledge will be explained. The inventor has discovered a problem that in a display device in which a decorative layer is disposed on the observer side of a display panel and the pattern of the decorative layer can be visually recognized in a display area where an image is displayed and a peripheral area surrounding the display area, depending on the illuminance of incident light on the display device, the boundary between the display area and the peripheral area may be easily visually recognized.

[0010] According to the inventors' research, when the illuminance of incident light is relatively low, the luminance ratio, which is the ratio of the luminance of the display area to the luminance of the surrounding area, may become relatively large near the boundary between the display area and the surrounding area. When the luminance ratio near the boundary is large, the boundary between the display area and the surrounding area becomes easier to see. Therefore, if the luminance ratio near the boundary is greater than a threshold, it is useful to control that luminance ratio to be below the threshold.

[0011] In the following, identical or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant explanations will be omitted where appropriate. Furthermore, the dimensions of the members in each drawing will be enlarged or reduced as appropriate for ease of understanding.

[0012] Figure 1 shows the configuration of the display device 1 according to the embodiment. While an example of a vehicle-mounted display device 1 is described, the use of the display device 1 is not particularly limited. The display device 1 may, for example, be a display device for a portable electronic device or a display device for a stationary electronic device.

[0013] The display device 1 is installed, for example, near the center of the center console inside the vehicle. The display device 1 displays various types of information. The display device 1 comprises a display unit 10, a control circuit 20, and an illuminance sensor 22.

[0014] Various devices for displaying images can be used as the display unit 10. The display unit 10 displays an image by emitting image light from the display surface. In this embodiment, an example of the display unit 10 being a liquid crystal display is described, but the display unit 10 may also be a self-emissive display such as an organic EL display.

[0015] The display unit 10 includes a display panel 12 and a backlight 14. The display unit 10 also has a surface layer, which will be described later, but is omitted in Figure 1. The display unit 10 may have known components such as an optical sheet and a protective layer, which are not shown.

[0016] The display panel 12 is a liquid crystal panel. The backlight 14 is a direct-lit backlight. The backlight 14 is located behind the display panel 12 and illuminates the display panel 12 with light. The backlight 14 includes multiple light sources 16 that illuminate the display panel 12. Each of the multiple light sources 16 has a light-emitting diode (LED) (not shown) on it. The multiple light sources 16 are arranged, for example, in a matrix. Each light source 16 constitutes a light-emitting area. The multiple light sources 16 do not necessarily have to be arranged regularly and may be arranged irregularly depending on the shape of the display panel 12 or the content to be displayed. The brightness of each light source 16 can be controlled individually.

[0017] The control circuit 20 displays an image on the display panel 12 via a liquid crystal drive circuit (not shown) based on image data supplied from an external source. The control circuit 20 controls the backlight 14 via a light source drive circuit (not shown) and controls the brightness of each light source 16.

[0018] The illuminance sensor 22 detects the illuminance of the light incident on the display unit 10 and outputs a signal indicating the detected illuminance to the control circuit 20. From the observer's perspective, the illuminance sensor 22 is located next to the display panel 12. This allows it to detect an illuminance close to the illuminance of the ambient light incident on the display panel 12. The control circuit 20 controls the display unit 10 based on the illuminance detected by the illuminance sensor 22.

[0019] The control circuit 20 includes a feature detection unit 30, a first acquisition unit 32, a second acquisition unit 34, a derivation unit 36, a determination unit 38, a correction value creation unit 40, an image correction unit 42, and a backlight control unit 44. Details of the processing of the control circuit 20 will be described later. The configuration of the control circuit 20 can be realized through the cooperation of hardware resources and software resources, or solely through hardware resources. As hardware resources, a microcomputer, CPU, DSP, ROM, RAM, ASIC, FPGA, and other LSIs can be used. As software resources, programs such as firmware can be used. In this embodiment, the operation of the control circuit 20 realizes the functions of the feature detection unit 30, the first acquisition unit 32, the second acquisition unit 34, the derivation unit 36, the determination unit 38, the correction value creation unit 40, the image correction unit 42, and the backlight control unit 44.

[0020] Figure 2 is a plan view of the display unit 10 shown in Figure 1. Figure 2 is a view of the display unit 10 from the front side, i.e., the observer side. Figure 3 is a longitudinal cross-sectional view of the display unit 10 shown in Figure 2 along line III-III.

[0021] The display unit 10 has a display area A1 for displaying an image and a peripheral area A2 surrounding the display area A1. The display area A1 is, for example, rectangular. The display area A1 is the area corresponding to the display surface of the display panel 12. The display panel 12 displays an image in the display area A1. No image is displayed in the peripheral area A2.

[0022] Display area A1 includes a first end area A11, which is located near the surrounding area A2. The first end area A11 is adjacent to the surrounding area A2. The first end area A11 has, for example, a rectangular frame shape. For example, the first end area A11 contains the outermost pixels of the display panel 12. That is, the first end area A11 contains the pixels of the top row, the bottom row, the leftmost column, and the rightmost column of the display panel 12 as seen from the observer's perspective. In Figures 2 and 3, the size of the first end area A11 is exaggerated to make the drawings clearer. Note that the first end area A11 may contain pixels in multiple rows and multiple columns.

[0023] The display area A1 is located near the surrounding area A2 and includes a second end area A12, which includes the first end area A11. The second end area A12 is adjacent to the surrounding area A2. The second end area A12 has, for example, a rectangular frame shape. The size of the second end area A12 is determined by the control circuit 20 according to the display image displayed in the display area A1, as will be described later.

[0024] The displayed image includes the first end image displayed in the second end region A12. The first end image includes the second end image displayed in the first end region A11.

[0025] The backlight 14 has multiple light sources 16, including an end light source group 24 consisting of multiple light sources 16 arranged in overlapping positions in the second end region A12. Figure 3 shows some of the light sources 16.

[0026] The surface layer 17 is translucent. The surface layer 17 covers at least a portion of the display area A1 and at least a portion of the peripheral area A2. In this embodiment, the surface layer 17 covers the entirety of the display area A1 and the entirety of the peripheral area A2. The surface layer 17 is located on the observer side of the display panel 12. As viewed from the observer side, the surface layer 17 is larger than the display panel 12. As viewed from the observer side, the surface layer 17 is positioned to overlap the entirety of the display panel 12. As viewed from the observer side, the surface layer 17 has a portion that overlaps the display panel 12, i.e., a first portion 17a that overlaps the display area A1, and a portion that does not overlap the display panel 12, i.e., a second portion 17b that overlaps the peripheral area A2. The first portion 17a has a third portion 17c that overlaps the first end area A11.

[0027] The surface layer 17 may be a cover panel without decoration, or it may be a decorative layer 18. In this embodiment, the surface layer 17 is a decorative layer 18. The decorative layer 18 has a pattern, such as a wood grain pattern, and is translucent. The decorative layer 18 may be a decorative sheet with a pattern, or it may be a layer provided by printing or transferring ink onto a translucent cover (not shown).

[0028] The display image shown on the display panel 12 is visible to the observer via the decorative layer 18. The pattern of the decorative layer 18 is also visible to the observer, and the observer can see the pattern of the decorative layer 18 superimposed on the display image in the display area A1. The observer can also see the pattern of the decorative layer 18 in the surrounding area A2. This improves the design of the display device 1. For example, by using a decorative layer 18 with a pattern that matches the interior of the vehicle, the display screen of the display device 1 can be made to blend in with the interior of the vehicle.

[0029] As shown in Figure 3, the brightness of the image light emitted from the display panel 12 is L(lm / sr / m 2 Assuming that the transmittance of the decorative layer 18 is T (%), the brightness of the display image displayed in the display area A1 on the observer-facing side of the decorative layer 18 is LT / 100 (cd / m²). 2 It is represented as follows:

[0030] The illuminance of ambient light incident on the decorative layer 18 is E (lm / m 2 Assuming that the reflectance of the decorative layer 18 is R (%) and the reflection coefficient of the decorative layer 18 is k, the luminance of the ambient light reflected by the decorative layer 18 is EkR / 100 (cd / m²). 2 It is represented as follows:

[0031] Therefore, the luminance of the decorative layer 18 on the observer-facing side in the display area A1 is (LT + EkR) / 100 (cd / m²). 2 ) The luminance on the observer-facing side of the decorative layer 18 in the peripheral region A2 is EkR / 100 (cd / m²). 2 )

[0032] The processing of the control circuit 20 will be explained below with reference to Figures 1 to 3. The first acquisition unit 32 acquires illuminance E from the illuminance sensor 22. The second acquisition unit 34 acquires the luminance L of the second end image displayed in the first end region A11 from the image data of the displayed image. The luminance L of the second end image is, for example, the average value of the luminances of multiple pixels in the first end region A11. The luminance of a pixel can be derived from the grayscale value of the pixel in the image data and the luminance of the backlight 14.

[0033] The derivation unit 36 ​​derives a luminance ratio ((LT+EkR) / EkR), which is the ratio of the luminance of the first end region A11 to the luminance of the surrounding region A2, based on the acquired illuminance E and the acquired luminance L of the second end image. The luminance of the first end region A11 is, for example, the luminance on the observer-side surface of the third portion 17c. The luminance of the surrounding region A2 is, for example, the luminance on the observer-side surface of the second portion 17b. The luminance ratio is the ratio of the luminance of the first end region A11 to the luminance of the surrounding region A2. The luminance ratio can also be called the contrast. The values ​​of T, k, and R are pre-stored in a memory unit (not shown).

[0034] The control circuit 20 determines whether the derived luminance ratio is greater than a predetermined luminance ratio threshold. If the luminance ratio is less than or equal to the luminance ratio threshold, the control circuit 20 displays the image on the display panel 12 according to the image data.

[0035] The control circuit 20 controls the display unit 10 so that the luminance ratio becomes less than or equal to the luminance ratio threshold if the luminance ratio is greater than the luminance ratio threshold. Specifically, the control circuit 20 controls the display panel 12 or the backlight 14 so that the luminance ratio becomes less than or equal to the luminance ratio threshold.

[0036] The luminance ratio threshold is set to a value of, for example, 10 or less. The luminance ratio threshold can be determined appropriately through experimentation or simulation. Generally, when the luminance ratio is 10 or less, the difference in luminance between display area A1 and surrounding area A2 is difficult for the observer to perceive, and therefore the boundary between display area A1 and surrounding area A2 is difficult for the observer to see. The closer the luminance ratio is to 1, the more difficult it becomes for the observer to perceive the boundary between display area A1 and surrounding area A2. An example where the luminance ratio threshold is 2 is described below.

[0037] The control circuit 20 determines whether the brightness of the second-end image is greater than a predetermined brightness threshold if the brightness ratio is greater than the brightness ratio threshold.

[0038] The luminance threshold is a threshold used to determine whether it is possible to reduce the luminance ratio by reducing the luminance of the second-end image. The luminance threshold can be determined as appropriate through experimentation or simulation. For example, the luminance threshold may be set so that the luminance of the second-end image becomes less than the luminance threshold when many of the pixels constituting the second-end image are displayed as black at the lowest grayscale value. Alternatively, the luminance threshold may be set so that the luminance of the second-end image becomes less than the luminance threshold when one of the pixels constituting the second-end image is displayed as black at the lowest grayscale value.

[0039] If the control circuit 20 determines that the brightness of the second end image is greater than the brightness threshold, it controls the display panel 12 to perform image brightness reduction processing to reduce the brightness of the first end image so that the brightness ratio becomes less than or equal to the brightness ratio threshold. The control circuit 20 performs image brightness reduction processing so that the brightness of the first end image gradually decreases from the center of the display area A1 toward the edge of the display area A1.

[0040] If the control circuit 20 determines that the brightness of the second end image is below the brightness threshold, it controls the backlight 14 to perform a light intensity reduction process that reduces the light intensity of the end light source group 24 so that the brightness ratio is below the brightness ratio threshold. Even if it is difficult to reduce the brightness ratio by controlling the display panel 12, the brightness ratio can be reduced by reducing the light intensity of the end light source group 24.

[0041] First, we will explain specific examples of image brightness reduction processing, and then we will discuss specific examples of light intensity reduction processing later.

[0042] FIG. 4 shows the luminance of each position of the display unit 10 when the illuminance of external light incident on the display unit 10 in FIG. 3 is relatively high. The positions shown in FIG. 4 indicate the horizontal positions in the vicinity of the peripheral region A2 on the left side and the second end region A12 in FIG. 3. The luminance shown in FIG. 4 is, for example, the luminance of each position on the observer side surface of the decorative layer 18. The same applies to the following drawings.

[0043] FIG. 4 shows an example where the luminance of the peripheral region A2 is 450 (cd / m 2 ), and the luminance of the display image displayed in the display region A1 is 450 (cd / m 2 ) regardless of the position. In this case, since the luminance of the display region A1 is 900 (cd / m 2 ), the luminance of the first end region A11 is also 900 (cd / m 2 ). Therefore, the luminance ratio between the luminance of the first end region A11 and the luminance of the peripheral region A2 is 900 / 450 = 2. Therefore, the boundary between the display region A1 and the peripheral region A2 is difficult for the observer to visually recognize.

[0044] The determination unit 38 determines whether the luminance ratio derived by the derivation unit 36 is greater than the luminance ratio threshold. When the luminance ratio is less than or equal to the luminance ratio threshold, the image correction unit 42 does not correct the input image data and outputs the gradation value of each pixel in the image data to the display panel 12. Each of the plurality of pixels of the display panel 12 is controlled to have a light transmittance according to the gradation value.

[0045] When the luminance ratio is less than or equal to the luminance ratio threshold, the backlight control unit 44 outputs a predetermined reference current value to the backlight 14. The reference current value is a value at which each of the plurality of light sources 16 can emit light at a predetermined luminance, for example, the maximum luminance. A current of the reference current value flows through each of the plurality of light sources 16 in the backlight 14.

[0046] Figure 5 shows the brightness of each position of the display unit 10 before image correction when the ambient light intensity incident on the display unit 10 in Figure 3 is relatively low. Each position shown in Figure 5 corresponds to each position shown in Figure 4. Figure 5 shows the brightness of the display unit 10 in dark conditions such as at night or inside a tunnel.

[0047] The ambient light intensity is lower than in the example in Figure 4, and the brightness of the surrounding area A2 is 10 (cd / m²). 2 Assume that the brightness has decreased to ). The brightness of the display image displayed in display area A1 is the same as in Figure 4. In this case, the brightness of display area A1 is 460 (cd / m²) regardless of position. 2 Therefore, the brightness of the first end region A11 is also 460 (cd / m²). 2 Therefore, the luminance ratio between the luminance of the first end region A11 and the luminance of the surrounding region A2 is 460 / 10 = 46. As a result, the difference in luminance between the display region A1 and the surrounding region A2 becomes more easily recognizable to the observer, and the boundary between the display region A1 and the surrounding region A2 becomes more easily visible to the observer.

[0048] In this example, the brightness of the second end image is assumed to be greater than the brightness threshold. The determination unit 38 determines whether the brightness of the second end image is greater than a predetermined brightness threshold. If the brightness ratio is greater than the brightness ratio threshold, and the brightness of the second end image is greater than the brightness threshold, the correction value creation unit 40 creates a correction value for each pixel of the first end image so that the brightness of the first end image gradually decreases from the center of the display area A1 toward the edge of the display area A1. The correction value creation unit 40 creates a correction value for each pixel of the second end image so that the brightness of the second end image decreases to a value of (brightness ratio threshold - 1) times the brightness of the surrounding area A2. The correction value creation unit 40 creates correction values ​​so that the brightness of each pixel of the display images other than the first end image is not corrected. The correction value for each pixel of the display images other than the first end image is, for example, 1.

[0049] The image correction unit 42 multiplies the correction value for each pixel created by the correction value creation unit 40 by the grayscale value of the corresponding pixel in the image data, and outputs the resulting grayscale value for each pixel to the display panel 12. The above processing by the correction value creation unit 40 and the image correction unit 42 corresponds to image brightness reduction processing. As a result, the brightness of each position in the display unit 10 is controlled to the values ​​shown in Figure 6.

[0050] Figure 6 shows the image-corrected brightness of each position of the display unit 10 when the illuminance of ambient light incident on the display unit 10 in Figure 3 is relatively low. Each position shown in Figure 6 corresponds to each position shown in Figure 4.

[0051] The display image shown in display area A1 other than the second end area A12 is not corrected, so its brightness is 450 (cd / m²) regardless of position. 2 ) The brightness of the second end image displayed in the first end region A11 is corrected to 10 (cd / m²). 2 The brightness of the first end image displayed in the second end region A12 decreases as it approaches the surrounding region A2 due to the correction. The brightness of the first end region A11 is 20 (cd / m²). 2 Therefore, the luminance ratio, which is the ratio of the luminance of the first end region A11 to the luminance of the surrounding region A2, is 20 / 10 = 2, which is equal to the luminance ratio threshold. By correcting, the luminance ratio can be made smaller than shown in Figure 5, making it difficult for the observer to perceive the boundary between the display region A1 and the surrounding region A2. In addition, since the luminance of the display image displayed in the display region A1 other than the second end region A12 is the same as in the case of Figure 4, the decrease in the visibility of the display image can be suppressed.

[0052] Next, we will explain the image brightness reduction process in more detail. The control circuit 20 determines whether the displayed image is a central image, where only the central region contains information, or a whole image, where the entire image contains information, and determines the content of the image brightness reduction process according to the determination result. This allows the control circuit 20 to perform image brightness reduction processing according to the type of displayed image. When the control circuit 20 determines that the displayed image is a central image, it performs image brightness reduction processing so that the brightness of the first edge image decreases linearly from the center of the display area A1 toward the edge of the display area A1. The processing described in Figure 6 is the processing performed when the displayed image is a central image.

[0053] The feature detection unit 30 detects features of the display image from the input image data. The feature detection unit 30 detects, for example, the position of edges as features of the display image and outputs the detected edge positions to the determination unit 38. Known techniques can be used to detect the position of edges. For example, the feature detection unit 30 converts the display image to grayscale, extracts multiple edges from the grayscale image, and detects the positions of the extracted multiple edges.

[0054] The determination unit 38 determines whether the displayed image is a central image or a whole image based on the position of the detected edges, and outputs the determination result to the correction value creation unit 40. The determination unit 38 determines that the displayed image is a central image if the edges are located only in the central region of the displayed image and there are no edges in the edge regions, which are areas of the displayed image other than the central region. The size of the central region is determined by the position of the outermost edge. The determination unit 38 determines that the displayed image is a whole image if the edges are located at the edges of the displayed image.

[0055] Figure 7 is a diagram illustrating the image brightness reduction process for the central image. Figure 7(a) shows the display image shown on the display panel 12. Figure 7(b) schematically shows the brightness at each position along the AA line of the display image in Figure 7(a). The display image includes multiple icons 50 located in the central region A20. The edge region of the display image is the area surrounding the central region where the multiple icons 50 are located, and is displayed in white, for example, and contains no information. The edge region of the display image is located in the second edge region A12.

[0056] Figure 7(c) shows the brightness correction values ​​for each position of the displayed image corresponding to Figure 7(b). The correction value creation unit 40 creates correction values ​​for each pixel of the first end image so that, if the brightness ratio is greater than the brightness ratio threshold, the brightness of the second end image is greater than the brightness threshold, and the displayed image is the central image, the brightness of the first end image decreases linearly from the center of the display area A1 toward the edge of the display area A1. Based on the positions of multiple edges detected by the feature detection unit 30, the correction value creation unit 40 identifies the area where no edges exist as the second end area A12, and thereby identifies the first end image to be displayed in the second end area A12.

[0057] Figure 7(d) shows the brightness of each position in the displayed image corresponding to Figure 7(b) after correction by multiplying by the correction value in Figure 7(c). Figure 7(e) schematically shows the corrected displayed image corresponding to the brightness shown in Figure 7(d). In the corrected displayed image, the brightness of the first end image decreases linearly, making the brightness change of the first end image according to the position less noticeable. On the other hand, the multiple icons 50 located outside the second end region A12 are displayed without brightness correction. In other words, the multiple icons 50 are displayed without a decrease in brightness, thus suppressing a decrease in the visibility of the multiple icons 50.

[0058] Figure 8 is a diagram illustrating the correction values ​​in the display image of Figure 7. Figure 8(a) shows a portion of the display area A1 shown in Figure 7(a). Pixel P1 is the leftmost pixel in the display image. Pixel P2 is the pixel located on the left edge of icon 50. Pixels P1 and P2 are located in the same row.

[0059] Figure 8(b) shows the uncorrected and corrected brightness at each pixel position from pixel P1 to pixel P2 shown in Figure 8(a) of the displayed image. The correction value creation unit 40 sets a predetermined reference line L1 with a predetermined slope that passes through the corrected brightness of pixel P1 at the position of pixel P1. The slope of the reference line L1 can be appropriately determined by experiment or simulation. The slope of the reference line L1 is determined so as to satisfy the condition that the brightness change becomes less noticeable when the brightness at each position of the displayed image is a value on the reference line L1. The slope of the reference line L1 is, for example, 2 (cd / m 2 ( / 1 pixel). The slope of the reference line L1 is, for example, a constant value independent of the displayed image.

[0060] The correction value creation unit 40 creates correction values ​​such that, if the uncorrected brightness of pixel P2 is less than or equal to the value of the reference line L1 at the position of pixel P2, the corrected brightness at each position between pixel P1 and pixel P2 lies on the line connecting the corrected brightness of pixel P1 and the uncorrected brightness of pixel P2. Since the brightness of pixel P2 is not corrected, the correction value for pixel P2 is 1. In this case, the slope of the line connecting the corrected brightness of pixel P1 and the brightness of pixel P2 is smaller than the slope of the reference line L1, making the brightness change in the first edge image less noticeable.

[0061] Figure 9 illustrates the correction values ​​in another display image. Figure 9(a) shows an example where icon 50 is closer to the edge of display area A1 than in the example shown in Figure 8(a). Figure 9(b) shows the uncorrected and corrected brightness of each pixel position from pixel P1 to pixel P2 shown in Figure 9(a) in the display image. Let pixel P3 be the pixel next to pixel P2 in the second edge area A12. Pixels P1, P2, and P3 are located in the same row.

[0062] The correction value creation unit 40 creates correction values ​​such that, if the uncorrected brightness of pixel P2 is greater than the value of the reference line L1 at the position of pixel P2, the corrected brightness of each position between pixel P1 and pixel P3 becomes a value on the reference line L1. Since the brightness of pixel P2 is not corrected, the correction value of pixel P2 is 1. As a result, the brightness of the first edge image decreases linearly from the center of the display area A1 towards the edge of the display area A1. In this case, the line connecting the corrected brightness of pixel P1 and the corrected brightness of pixel P3 coincides with the reference line L1, making the brightness change from pixel P1 to pixel P3 less noticeable.

[0063] The slope of the reference line L1 may be determined for each displayed image. For example, the slope of the reference line L1 may be determined such that the reference line L1 passes through a point at the position of pixel P2 where the brightness of the first end region A11 is obtained by multiplying the brightness by a brightness threshold.

[0064] Next, we will explain the image brightness reduction process for the overall image, focusing on the differences from the image brightness reduction process for the central image. When the control circuit 20 determines that the displayed image is the overall image, it performs an image brightness reduction process so that the brightness of the first edge image decreases non-linearly from the center of the display area A1 toward the edge of the display area A1.

[0065] Figure 10 is a diagram illustrating the image brightness reduction process for the overall image. Figure 10(a) shows the display image shown on the display panel 12. Figure 10(b) schematically shows the brightness at each position along the BB line of the display image shown in Figure 10(a). Here, we show an example where the display image is an overall image that displays a map image across the entire display panel 12. In the case of an overall image, the second end regions A12 are predetermined. The left and right second end regions A12 each contain at least 1 / 10 of the number of pixels in the row direction of the display panel 12. The upper and lower second end regions A12 each contain at least 1 / 10 of the number of pixels in the column direction of the display panel 12.

[0066] Figure 10(c) shows the brightness correction values ​​for each position of the displayed image corresponding to Figure 10(b). The correction value creation unit 40 creates correction values ​​for each pixel of the first end image so that the brightness of the first end image decreases non-linearly from the center of the display area A1 toward the edge of the display area A1, when the brightness ratio is greater than the brightness ratio threshold, the brightness of the second end image is greater than the brightness threshold, and the displayed image is the whole image. The correction value creation unit 40 creates correction values ​​so that the brightness of the first end image decreases more significantly as it approaches the edge of the display area A1. The correction value creation unit 40 identifies the first end image in a predetermined second end area A12.

[0067] The correction value creation unit 40 creates correction values ​​for each pixel of the first end image, for example, by using gamma correction. The correction value creation unit 40 calculates the correction value between the correction value of pixel P1 and the correction value of pixel P2 using y=x γ It is created based on the gamma curve represented by γ, for example, 1 / 2.2. The correction value for pixel P1 is determined as explained with respect to Figures 5 and 6. The correction value for pixel P2 is 1.

[0068] Figure 10(d) shows the brightness of each position in the displayed image corresponding to Figure 10(b) after correction by multiplying by the correction value in Figure 10(c). Figure 10(e) schematically shows the corrected displayed image corresponding to the brightness shown in Figure 10(d). In the corrected displayed image, the decrease in visibility of the part of the first edge image that is close to the center of display area A1 can be suppressed. In addition, since the brightness of the areas other than the second edge area A12 is the same as the brightness before correction, the decrease in visibility of the central area of ​​the displayed image can be suppressed.

[0069] Next, we will explain a specific example of light intensity reduction processing. Figure 11 shows the brightness of each position of the display unit 10 before correction when the illuminance of ambient light incident on the display unit 10 in Figure 1 is relatively low and the second end region A12 is displayed in black. Figure 11 shows the brightness of the display unit 10 in a dark environment, such as at night or inside a tunnel.

[0070] Figure 11 shows that the brightness of the peripheral region A2 is 0.1 (cd / m²).2 ) and the brightness of the display image displayed near the edge of display area A1 is 2 (cd / m²) regardless of position. 2 An example of this is shown. The grayscale value of each pixel of the display image displayed near the edge of display area A1 is the minimum value. The brightness of the second edge image is below the brightness threshold. Each light source 16 of the backlight 14, including the edge light source group 24, is emitting light at maximum brightness. Here, when a light source 16 is emitting light at maximum brightness, it is sometimes said that the light source 16 is emitting light at 100% light intensity. The current value that can make the light source 16 emit light at 100% light intensity is sometimes called the 100% current value. In other words, the 100% current value is the reference current value. In the example in Figure 11, each light source 16 is driven at the 100% current value.

[0071] In this case, the brightness of display area A1 is 2.1 cd / m² regardless of position. 2 Therefore, the brightness of the first end region A11 is also 2.1 (cd / m²). 2 Therefore, the luminance ratio between the luminance of the first end region A11 and the luminance of the surrounding region A2 is 2.1 / 0.1 = 21. Thus, in this state, the boundary between the display region A1 and the surrounding region A2 is easily visible to the observer.

[0072] When light intensity reduction processing is performed, the second edge region A12 is predetermined. For example, the second edge region A12 can be set to the case where the displayed image is a whole image.

[0073] Note that the central area of ​​display area A1, which is not shown in the diagram, contains icons, for example, several hundred (cd / m²). 2 It may be displayed at the brightness level of )

[0074] When the luminance ratio is greater than the luminance ratio threshold and the luminance of the second end image is less than or equal to the luminance threshold, the control circuit 20 performs a light intensity reduction process so that the light intensity of the end light source group 24 gradually decreases from the center of the display area A1 toward the edge of the display area A1, for example, in a linear manner.

[0075] Specifically, the correction value creation unit 40 creates a correction value for the current value of the end light source group 24 so that the light intensity of the end light source group 24 decreases linearly from the center of the display area A1 towards the edge of the display area A1. The correction value creation unit 40 creates a correction value so that the brightness of the second end image decreases to a value of (brightness ratio threshold - 1) times the brightness of the surrounding area A2. The correction value creation unit 40 creates a correction value so that the current values ​​of the light sources 16 other than the end light source group 24 do not change.

[0076] The backlight control unit 44 corrects the reference current value by multiplying it by the correction value created by the correction value creation unit 40, and outputs the corrected current value to the backlight 14. The above processing by the correction value creation unit 40 and the backlight control unit 44 corresponds to a light intensity reduction process. As a result, the brightness of each position of the display unit 10 is controlled to the values ​​shown in Figure 12.

[0077] Figure 12 shows the corrected brightness of each position of the display unit 10 when the illuminance of ambient light incident on the display unit 10 in Figure 1 is relatively low and the second end region A12 is displayed in black. The positions shown in Figure 12 correspond to the positions shown in Figure 11.

[0078] In the end light source group 24, the light source 16 at the edge of display area A1 is controlled to zero current. As a result, the light source 16 at the edge of display area A1 is turned off. In the end light source group 24, the light source 16 in the center of display area A1 is controlled to 50% of the reference current value. As a result, the light intensity of the light source 16 in the center of display area A1 is reduced to less than 100%.

[0079] The brightness of the display image shown in display area A1 near the second end region A12 is 2 (cd / m²). 2 The brightness of the second end image displayed in the first end region A11 is corrected to 0.1 (cd / m²). 2 The brightness of the first-end image displayed in the second-end region A12 decreases as it approaches the peripheral region A2.

[0080] The luminance of the first end region A11 is 0.2 (cd / m²). 2 Therefore, the luminance ratio between the luminance of the first end region A11 and the luminance of the surrounding region A2 is 0.2 / 0.1=2, which is equal to the luminance ratio threshold. Since the luminance ratio can be made smaller by the correction than in the case shown in Figure 11, the boundary between the display region A1 and the surrounding region A2 can be made less visible to the observer. In addition, since the luminance decreases linearly within the second end region A12, the change in luminance of the first end image depending on the position can be made less noticeable. Furthermore, since the luminance of the display image displayed in the display region A1 other than the second end region A12 is the same as in the case of Figure 11, the decrease in the visibility of the display image can be suppressed.

[0081] Figure 13 is a diagram illustrating the correction values ​​in the light intensity reduction process. Figure 13 shows the corrected brightness at each pixel position from pixel P1 to pixel P2 in the second edge region A12. The brightness of pixel P2 remains unchanged before and after correction.

[0082] The correction value creation unit 40 sets a reference line L1 that passes through the corrected brightness of pixel P1 at the position of pixel P1. The reference line L1 is the same as the one described in the image brightness reduction process, for example. If the uncorrected brightness of pixel P2 is less than or equal to the value of the reference line L1 at the position of pixel P2, the correction value creation unit 40 creates a correction value such that the corrected brightness at each position between pixel P1 and pixel P2 lies on the line connecting the corrected brightness of pixel P1 and the uncorrected brightness of pixel P2. In this case, the slope of the line connecting the corrected brightness of pixel P1 and the brightness of pixel P2 is smaller than the slope of the reference line L1, making it less likely for brightness changes in the first end image to be noticeable.

[0083] Figure 14 is a diagram illustrating the correction values ​​in another displayed image. Figure 14 shows an example where the grayscale value of pixel P2 is larger than the example shown in Figure 13. Let pixel P3 be the pixel adjacent to pixel P2 in the second edge region A12.

[0084] The correction value creation unit 40 creates correction values ​​such that, if the uncorrected brightness of pixel P2 is greater than the value of the reference line L1 at the position of pixel P2, the corrected brightness of each position between pixel P1 and pixel P3 becomes a value on the reference line L1. The brightness of pixel P2 is not corrected. As a result, the brightness of the first edge image decreases linearly from the center of the display area A1 towards the edge of the display area A1. In this case, the line connecting the corrected brightness of pixel P1 and the corrected brightness of pixel P3 coincides with the reference line L1, making the brightness change from pixel P1 to pixel P3 less noticeable.

[0085] Figure 15 is a flowchart showing the processing of the control circuit 20 in Figure 1. The control circuit 20 acquires illuminance from the illuminance sensor 22 (S10). The control circuit 20 determines whether the luminance ratio is greater than the luminance ratio threshold (S12). If the control circuit 20 determines that the luminance ratio is not greater than the luminance ratio threshold (N in S12), the process returns to S10. If the control circuit 20 determines that the luminance ratio is greater than the luminance ratio threshold (Y in S12), the control circuit 20 determines whether the luminance of the second end image is greater than the luminance threshold (S14). If the control circuit 20 determines that the luminance of the second end image is not greater than the luminance threshold (N in S14), the control circuit 20 performs a light intensity reduction process (S16), and the process returns to S10.

[0086] If the control circuit 20 determines that the brightness of the second-end image is greater than the brightness threshold (Y in S14), it determines whether the displayed image is the central image or not (S18). If it determines that the displayed image is the central image (Y in S18), the control circuit 20 performs a linear image brightness reduction process (S20), and the process returns to S10. If it determines that the displayed image is not the central image (N in S18), the control circuit 20 performs a nonlinear image brightness reduction process (S22), and the process returns to S10.

[0087] As described above, according to the embodiment, when the luminance ratio is greater than the luminance ratio threshold, the display unit 10 is controlled so that the luminance ratio becomes less than or equal to the luminance ratio threshold, making it difficult to perceive the boundary between the display area A1 and the surrounding area A2.

[0088] The present disclosure has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible for each component or combination of processing processes, and that such modifications are also within the scope of the present disclosure.

[0089] For example, if the luminance ratio is greater than the luminance ratio threshold and the luminance of the second-end image is greater than the luminance threshold, the control circuit 20 may control both the display panel 12 and the backlight 14 to reduce image luminance and reduce light intensity so that the luminance ratio becomes less than or equal to the luminance ratio threshold. This modified example improves the degree of control flexibility.

[0090] One aspect of this disclosure is as follows:

[0091] [Item 1] A display unit having a display area for displaying an image and a peripheral area surrounding the display area, The system includes an illuminance sensor that detects the illuminance of incident light, a control circuit that acquires the illuminance and controls the display unit, The display area includes a first end region which is located near the peripheral region. The aforementioned control circuit is Based on the illuminance and the image data of the display image, a luminance ratio is derived, which is the ratio of the luminance of the first end region to the luminance of the surrounding region. If the luminance ratio is greater than a predetermined luminance ratio threshold, the display unit is controlled so that the luminance ratio becomes less than or equal to the luminance ratio threshold. Display device. According to this embodiment, when the luminance ratio is greater than the luminance ratio threshold, the display unit is controlled so that the luminance ratio becomes less than or equal to the luminance ratio threshold, making it difficult to perceive the boundary between the display area and the surrounding area.

[0092] [Item 2] The display unit comprises a surface layer that covers at least a portion of the display area and at least a portion of the peripheral area. The surface layer has a first portion that overlaps with the display area and a second portion that overlaps with the peripheral area. The first portion has a third portion that overlaps with the first end region, The luminance of the first end region is the luminance on the observer-side surface of the third portion. The brightness of the peripheral region is the brightness on the observer-side surface of the second portion. The display device described in item 1. In this case, in a display device having a surface layer, the boundary between the display area and the surrounding area can be made less visible.

[0093] [Item 3] The aforementioned surface layer is a decorative layer having a pattern and being translucent. The display device described in item 2. In this case, the design of the display device can be improved. [Item 4] The aforementioned display unit is A display panel that displays the display image in the display area, It includes a backlight that includes multiple light sources and illuminates the display panel with light, The control circuit controls at least one of the display panel and the backlight so that the luminance ratio becomes less than or equal to the luminance ratio threshold when the luminance ratio is greater than the luminance ratio threshold. A display device as described in any one of items 1 through 3. In this case, in a display device having a display panel and a backlight, the boundary between the display area and the surrounding area can be made less visible.

[0094] [Item 5] The display area includes a second end area which is located near the peripheral area and includes the first end area. The display image includes the first end image displayed in the second end region, The control circuit, when the luminance ratio is greater than the luminance ratio threshold, controls the display panel and performs an image luminance reduction process to reduce the luminance of the first edge image so that the luminance ratio becomes less than or equal to the luminance ratio threshold. The display device described in item 4. In this case, the brightness ratio can be reduced by decreasing the brightness of the first-end image.

[0095] [Item 6] The first end image includes a second end image displayed in the first end region. The aforementioned control circuit is Determine whether the brightness of the second end image is greater than a predetermined brightness threshold, If it is determined that the brightness of the second end image is greater than the brightness threshold, the image brightness reduction process is performed. The display device described in item 5. In this case, the brightness ratio can be reduced by image brightness reduction processing.

[0096] [Item 7] The control circuit performs the image brightness reduction process such that the brightness of the first end image decreases from the center of the display area toward the edge of the display area. The display device described in item 5 or item 6. In this case, the brightness change of the first edge image depending on the position can be made less noticeable.

[0097] [Item 8] The control circuit determines whether the displayed image is a central image in which only the central region contains information, or a whole image in which the entire image contains information, and determines the content of the image brightness reduction process according to the determination result. A display device as described in any one of items 5 through 7. In this case, image brightness reduction processing can be performed according to the type of displayed image.

[0098] [Item 9] When the control circuit determines that the displayed image is the central image, it performs the image brightness reduction process such that the brightness of the first edge image decreases linearly from the center of the display area toward the edge of the display area. The display device described in item 8. In this case, the brightness change of the first edge image depending on the position can be made less noticeable.

[0099] [Item 10] When the control circuit determines that the displayed image is the overall image, it performs the image brightness reduction process such that the brightness of the first edge image decreases non-linearly from the center of the display area toward the edge of the display area. The display device described in item 8 or item 9. In this case, image brightness reduction processing can be performed to suppress the decrease in visibility of the portion of the first edge image that is closer to the center of the display area.

[0100] [Item 11] The display area includes a second end area which is located near the peripheral area and includes the first end area. The plurality of light sources have an end light source group consisting of a plurality of light sources arranged in overlapping positions in the second end region, The control circuit performs a light intensity reduction process to reduce the light intensity of the end light source group so that the luminance ratio is less than or equal to the luminance ratio threshold if the luminance ratio is greater than or equal to the luminance ratio threshold. The display device described in item 4. In this case, the luminance ratio can be reduced by decreasing the light intensity of the end light sources.

[0101] [Item 12] The display image includes the first end image displayed in the second end region, The first end image includes a second end image displayed in the first end region. The aforementioned control circuit is Determine whether the brightness of the second end image is less than or equal to a predetermined brightness threshold. If it is determined that the brightness of the second end image is below the brightness threshold, the light intensity reduction process is performed. The display device described in item 11. In this case, even if it is difficult to reduce the brightness ratio by controlling the display panel, the brightness ratio can still be reduced.

[0102] [Item 13] The control circuit performs the light intensity reduction process such that the light intensity of the end light source group decreases from the center of the display area toward the edge of the display area. The display device described in item 11 or item 12. In this case, the brightness change of the first edge image depending on the position can be made less noticeable.

[0103] [Item 14] The control circuit performs the light intensity reduction process such that the light intensity of the end light source group decreases linearly from the center of the display area toward the edge of the display area. The display device described in item 13. In this case, the brightness change of the first edge image depending on the position can be made less noticeable.

[0104] [Item 15] The illuminance sensor is provided, A display device as described in any one of items 1 through 14. In this case, a display device capable of detecting illuminance can be provided.

[0105] [Item 16] A control method for a display device comprising a display unit having a display area for displaying an image and a peripheral area surrounding the display area, wherein the display area includes a first end area which is located near the peripheral area, A step of obtaining the illuminance from an illuminance sensor that detects the illuminance of incident light, A step of deriving a luminance ratio, which is the ratio of the luminance of the first end region to the luminance of the surrounding region, based on the illuminance, If the luminance ratio is greater than a predetermined luminance ratio threshold, the display unit is controlled so that the luminance ratio becomes less than or equal to the luminance ratio threshold. A control method comprising the following features. According to this embodiment, the boundary between the display area and the surrounding area can be made less visible. [Explanation of symbols]

[0106] 1...Display device, 10...Display unit, 12...Display panel, 14...Backlight, 16...Light source, 17...Surface layer, 17a...First part, 17b...Second part, 17c...Third part, 18...Decorative layer, 20...Control circuit, 22...Illuminance sensor, 24...End light source group, 30...Feature detection unit, 32...First acquisition unit, 34...Second acquisition unit, 36...Derivation unit, 38...Determination unit, 40...Correction value creation unit, 42...Image correction unit, 44...Backlight control unit.

Claims

1. A display unit having a display area for displaying an image and a peripheral area surrounding the display area, The system includes an illuminance sensor that detects the illuminance of incident light, a control circuit that acquires the illuminance and controls the display unit, The display area includes a first end region which is located near the peripheral region. The aforementioned control circuit is Based on the illuminance and the image data of the display image, a luminance ratio is derived, which is the ratio of the luminance of the first end region to the luminance of the surrounding region. If the luminance ratio is greater than a predetermined luminance ratio threshold, the display unit is controlled so that the luminance ratio becomes less than or equal to the luminance ratio threshold. The aforementioned display unit is A display panel that displays the display image in the display area, It includes a backlight that includes multiple light sources and illuminates the display panel with light, The display area includes a second end area which is located near the peripheral area and includes the first end area. The display image includes the first end image displayed in the second end region, The control circuit, when the luminance ratio is greater than the luminance ratio threshold, controls the display panel and performs an image luminance reduction process to reduce the luminance of the first end image so that the luminance ratio becomes less than or equal to the luminance ratio threshold. The control circuit determines whether the displayed image is a central image in which only the central region contains information, or a whole image in which the entire image contains information, and determines the content of the image brightness reduction process according to the determination result. Display device.

2. The display unit comprises a surface layer that covers at least a portion of the display area and at least a portion of the peripheral area. The surface layer has a first portion that overlaps with the display area and a second portion that overlaps with the peripheral area. The first portion has a third portion that overlaps with the first end region, The luminance of the first end region is the luminance on the observer-side surface of the third portion. The brightness of the peripheral region is the brightness on the observer-side surface of the second portion. The display device according to claim 1.

3. The aforementioned surface layer is a decorative layer having a pattern and being translucent. The display device according to claim 2.

4. The first end image includes a second end image displayed in the first end region. The aforementioned control circuit is Determine whether the brightness of the second end image is greater than a predetermined brightness threshold, If it is determined that the brightness of the second end image is greater than the brightness threshold, the image brightness reduction process is performed. The display device according to claim 1.

5. The control circuit performs the image brightness reduction process such that the brightness of the first end image decreases from the center of the display area toward the edge of the display area. The display device according to claim 1 or claim 4.

6. When the control circuit determines that the displayed image is the central image, it performs the image brightness reduction process such that the brightness of the first edge image decreases linearly from the center of the display area toward the edge of the display area. The display device according to claim 1.

7. When the control circuit determines that the displayed image is the overall image, it performs the image brightness reduction process such that the brightness of the first end image decreases non-linearly from the center of the display area toward the edge of the display area. The display device according to claim 1.

8. The display area includes a second end area which is located near the peripheral area and includes the first end area. The plurality of light sources includes an end light source group consisting of a plurality of light sources arranged in overlapping positions in the second end region. The control circuit performs a light intensity reduction process to reduce the light intensity of the end light source group so that the luminance ratio is less than or equal to the luminance ratio threshold if the luminance ratio is greater than or equal to the luminance ratio threshold. The display device according to claim 1.

9. The display image includes the first end image displayed in the second end region, The first end image includes a second end image displayed in the first end region. The aforementioned control circuit is Determine whether the brightness of the second end image is less than or equal to a predetermined brightness threshold, If it is determined that the brightness of the second end image is below the brightness threshold, the light intensity reduction process is performed. The display device according to claim 8.

10. The control circuit performs the light intensity reduction process such that the light intensity of the end light source group decreases from the center of the display area toward the edge of the display area. The display device according to claim 8 or claim 9.

11. The control circuit performs the light intensity reduction process such that the light intensity of the end light source group decreases linearly from the center of the display area toward the edge of the display area. The display device according to claim 10.

12. The illuminance sensor is provided, The display device according to claim 1 or claim 2.

13. A control method for a display device comprising a display unit having a display area for displaying an image and a peripheral area surrounding the display area, wherein the display area includes a first end area which is located near the peripheral area, A step of obtaining the illuminance from an illuminance sensor that detects the illuminance of incident light, A step of deriving a luminance ratio, which is the ratio of the luminance of the first end region to the luminance of the surrounding region, based on the illuminance, If the luminance ratio is greater than a predetermined luminance ratio threshold, the display unit is controlled so that the luminance ratio becomes less than or equal to the luminance ratio threshold. Equipped with, The aforementioned display unit is A display panel that displays the display image in the display area, It includes a backlight that includes multiple light sources and illuminates the display panel with light, The display area includes a second end area which is located near the peripheral area and includes the first end area. The display image includes the first end image displayed in the second end region, In the step of controlling the display unit, if the luminance ratio is greater than the luminance ratio threshold, the display panel is controlled to perform an image luminance reduction process to reduce the luminance of the first end image so that the luminance ratio becomes less than or equal to the luminance ratio threshold. The method further includes the step of determining whether the displayed image is a central image in which only the central region contains information, or a whole image in which the entire image contains information, and determining the content of the image brightness reduction process according to the determination result. Control method.

Images