WO2021260939A1 - Light source control device, light source control method, image display device, program, and recording medium - Google Patents

Abstract

Provided is a light source control device for controlling a backlight, the brightness of which can be controlled in a plurality of regions, wherein a light source control value for each region is calculated from an input image signal (Da). Furthermore, a correction intensity (G) that increases as a brightness index of the input image signal (Da) decreases is calculated. When a light source control value (LSi) is greater than the brightness index for each region, a value, obtained by multiplying the correction intensity (G) by a value obtained by subtracting the brightness index from the light source control value (LSi) and adding the brightness index, is set as a correction light source control value (LSCi). When the light source control value (LSi) is equal to or less than the brightness index, the light source control value (LSi) is used as the correction light source control value (LSCi). Display can be performed with sufficient brightness according to an input image, and power consumption can be suppressed.

Description

Light source control device, light source control method, and image display device, as well as programs and recording media.

The present disclosure relates to a light source control device, a light source control method, and an image display device. The disclosure also relates to programs and recording media.

In an image display device equipped with a backlight, such as a liquid crystal display device, the backlight is divided into multiple areas for the main purpose of improving contrast and reducing power consumption, and local dimming is performed to control the emission brightness for each area. A technique called is used.

In an example of the conventional image display device, the brightness of the light source corresponding to the divided area is calculated based on the gradation value for each area of the input image, and the average value (average light source brightness) of the brightness of a plurality of light sources is calculated. The correction coefficient is calculated based on the average light source brightness, and the brightness of each light source is corrected using the correction coefficient. The correction coefficient is 1 when the average light source brightness is small, and is decreased as the average light source brightness increases (for example, Patent Document 1).

Japanese Patent No. 4818351 (paragraph 0007, paragraph 0043)

In the method of Patent Document 1, the brightness of each light source is corrected by using the correction coefficient calculated from the average light source brightness. Therefore, for example, an all-gray image (an image in which all pixels have intermediate gradation values) and a part of the image are bright. When the average value of the gradation values of all the pixels is the same as that of the all gray image, the correction coefficient is the same value. Therefore, there is a problem that a bright portion (a portion having a high gradation value) is not sufficiently brightly displayed in a partially bright image (a part of an image having a high gradation value).
Further, in the method of Patent Document 1, for example, the brightness of each light source when an all-gray image is input is corrected to be higher than the brightness of each light source when an all-white image is input. This is not appropriate from the viewpoint of reducing power consumption.

The present disclosure is for solving the above-mentioned problems, and aims to display with sufficient brightness according to the input image and to suppress power consumption.

The light source control device according to the present disclosure is
In a light source control device that controls a backlight that can control brightness in multiple areas
A feature amount calculation unit that calculates a feature amount indicating the brightness or brightness of an image for each of the regions from an input image signal, and a feature amount calculation unit.
A light source control value calculation unit that calculates a light source control value for each region of the backlight based on the feature amount of the region, and a light source control value calculation unit.
A comparison unit that compares the light source control value for each region with the brightness index of the input image signal and outputs the comparison result for the region.
A correction strength calculation unit that calculates the correction strength from the brightness index,
It is provided with a light source control value correction unit that generates a correction light source control value for the region from the comparison result for each region and the correction intensity.
The light source control value of each region calculated by the light source control value calculation unit is larger as the brightness or brightness of the image represented by the feature amount for the region is larger.
The correction strength calculated by the correction strength calculation unit is larger as the brightness index is smaller.
The light source control value correction unit is
When the comparison unit determines that the light source control value is larger than the brightness index, the brightness is obtained by multiplying the value obtained by subtracting the brightness index from the light source control value in the region by the correction intensity. The value obtained by adding the index is output as the correction light source control value.
When the comparison unit determines that the light source control value in each region is equal to or less than the brightness index, the light source control value in the region is output as the correction light source control value in the region.

According to the present disclosure, when the light source control value in each region is larger than the average light source control value, the value obtained by subtracting the average light source control value from the light source control value in the region is multiplied by the correction intensity. The value obtained by adding the average light source control value is output as the correction light source control value in the region. Therefore, when an all-gray image (an image of uniform overall and intermediate level) is input, the brightness of the backlight is not corrected. Therefore, the amount of light emitted from the backlight is smaller than that in the case of an all-white image (an image in which the entire image is white), whereby power consumption can be suppressed (energy saving is achieved). Further, in an image in which a part is bright, the bright part is displayed sufficiently bright.

It is a block diagram which shows the structure of the image display device which concerns on Embodiment 1. FIG. It is a figure which shows an example of the arrangement of the region formed by dividing a backlight. It is a block diagram which shows the structure of the light source control apparatus which concerns on Embodiment 1. FIG. It is a graph which shows an example of the relationship between the average light source control value and the correction intensity. It is a graph which shows an example of the relationship between the difference between a light source control value and an average light source control value, and a comparison value. It is a graph which shows the relationship between the light source control value and the correction light source control value. It is a table which shows the relationship between the content of an image and a correction light source control value. It is a table which shows the correction light source control value for the region which has a light source control value different from each other of an image. It is a block diagram which shows the structure of the light source control apparatus which concerns on Embodiment 2. FIG. It is a figure which shows an example of the light source control value of each area of a backlight. It is a figure which shows the other example of the light source control value of each area of a backlight. It is a block diagram which shows the structure of the image display device which concerns on Embodiment 3. FIG. It is a block diagram which shows the structure of the light source control apparatus which concerns on Embodiment 3. FIG. It is a block diagram which shows the structure of the image display device which concerns on Embodiment 4. FIG. It is a block diagram which shows the structure of the light source control apparatus which concerns on Embodiment 4. FIG. It is a block diagram which shows the structure of the image display device which concerns on Embodiment 5. It is a block diagram which shows the structure of the light source control apparatus which concerns on Embodiment 5. It is a block diagram which shows an example of the configuration in the case where the function of the light source control device of Embodiment 1 is realized by the computer including a single processor. It is a flowchart which shows the procedure of the process in the case of performing the same light source control as the light source control apparatus of Embodiment 1 with the configuration of FIG. It is a flowchart which shows the procedure of the process in the case of performing the same light source control as the light source control apparatus of Embodiment 4 with the same structure as FIG.

Embodiment 1.
FIG. 1 shows the configuration of the image display device according to the first embodiment. The image display device shown in FIG. 1 includes an image input terminal 1, a light source control device 100, an image signal processing unit 200, a display panel 300, and a backlight 400.

The display panel 300 is, for example, a liquid crystal display panel, but any panel may be used as long as the transmittance can be controlled for each pixel.

The backlight 400 is divided into a plurality of regions A1, A2, ... As shown in FIG. 2, for example, and the emission brightness, that is, the brightness can be controlled for each of the plurality of regions.

In the example shown in FIG. 2, the backlight 400 is divided into 9 in the vertical direction and 8 in the horizontal direction to form 72 regions A1 to A72 in total. However, the number of regions is not limited to 72 in this example. In the following, it is assumed that the areas A1 to A72 have the same area.

The backlight 400 may have one light emitter for each region, that is, a light source. The number of regions and the number of light sources may or may not match. For example, it may have a plurality of light sources in one area. The light source may be an LED. The light source is driven by the light source driving device 402. The light source driving device 402 includes, for example, a plurality of driving circuits provided corresponding to each of the plurality of light sources. The power consumption in each region of the backlight 400 is limited by the drive capability of each drive circuit.

An image signal (input image signal) Da is input to the image input terminal 1. The input image signal Da is a set of pixel signals for each of the plurality of pixels. The pixel signal may be referred to as an image signal for each pixel. The image signal for each pixel has, for example, red, green and blue component values.

The light source control device 100 calculates a light source control value LSi for each Ai (i is any of 1 to 72) in each of the plurality of regions A1 to A72 from the input image signal Da, and corrects the light source based on the light source control value LSi. The control value LSCi is calculated.
The light source control device 100 outputs a light source control value (first light source control value) LSi and a correction light source control value (second light source control value) LSCi.

The image signal processing unit 200 performs signal processing on the input image signal Da based on the light source control value LSi of each region output from the light source control device 100, and outputs the corrected image signal Db. This signal processing includes gradation correction for the image signal for each pixel. The above gradation correction is performed in order to compensate for the change in the intensity of the light emitted by the backlight 400 due to the change in the light source control value.

The display panel 300 controls the light transmittance of each pixel based on the corrected image signal Db output from the image signal processing unit 200.

The backlight 400 controls the brightness of the region based on the corrected light source control value LSSi of each region output from the light source control device 100. The brightness of each area is controlled by controlling the amount of light emitted from the light source that affects the brightness of each area.

FIG. 3 shows a configuration example of the light source control device 100 of FIG. The illustrated light source control device 100 includes a feature amount calculation unit 101, a light source control value calculation unit 102, an average value calculation unit 103, a correction intensity calculation unit 104, a comparison unit 105, and a light source control value correction unit 106. Be prepared.

The feature amount calculation unit 101 calculates the feature amount FQi for each of the plurality of regions A1 to A72 from the input image signal Da.

The light source control value calculation unit 102 calculates the light source control value (first light source control value) LSi for the region from the feature quantity FQi for each region calculated by the feature quantity calculation unit 101.

The average value calculation unit 103 calculates the average value LSave of the light source control value LSi calculated by the light source control value calculation unit 102 over the entire backlight 400.

The correction intensity calculation unit 104 calculates the correction intensity G from the average light source control value LSave calculated by the average value calculation unit 103.

The comparison unit 105 compares the light source control value LSi of each region calculated by the light source control value calculation unit 102 with the average light source control value LSave calculated by the average value calculation unit 103, and obtains a comparison value Ci indicating the comparison result. Output.

The light source control value correction unit 106 has a correction intensity G calculated by the correction intensity calculation unit 104, a comparison value Ci for each region output from the comparison unit 105, and an average light source control calculated by the average value calculation unit 103. Based on the value LSave, the light source control value LSi of each region is corrected, and the corrected light source control value (second light source control value) LSCi for the region is output.

To distinguish from the corrected light source control value LSCi, the light source control value LSi may be referred to as the light source control value before correction.

If it is necessary to delay the image signal in order to match the time required for calculation of various values based on the image signal, one or more delay sections (not shown) shall be provided at necessary locations to delay the image signal.

The image represented by the input image signal Da may be a still image or a moving image, and may or may not be accompanied by sound. In particular, although moving images are also called images, they are referred to as images in the present specification.

The average value has the same meaning as the total value (sum) due to its nature. For example, the average value of a plurality of light source control values is the total value of the plurality of light source control values divided by the number of the light source control values. , The average value can be replaced with the total value. Further, in digital data processing, a value proportional to the total value obtained by shifting the bits, deleting the lower bits, rounding up, rounding, or the like may have the same meaning as the average value. In that case, such a value can be used instead of the average value.

Hereinafter, the operation of each part of the light source control device 100 will be described in more detail.
The feature amount calculation unit 101 calculates the feature amount FQi for each region from the input image signal Da. As the feature amount FQi, for example, luminance or lightness is used.

The input image signal Da is composed of, for example, red, green and blue component values. In that case, the brightness is obtained by adding the component values of red, green, and blue with predetermined weights. The brightness can be the largest of the red, green, and blue component values in each pixel.

The light source control value calculation unit 102 is calculated from the peak value or average value of the feature amount FQi for each region calculated by the feature amount calculation unit 101, or the mixed value of the peak value and the average value (calculated from the peak value and the average value). The light source control value LSi for each region is calculated from the value) and the like.

For example, the peak value of the brightness in each region may be used as the light source control value LSi in that region. Then, the backlight 400 is controlled to emit bright light in a region in which a portion having a large component value of one or more colors occupies at least a part.

In obtaining the light source control value LSi of each region (attention region), the feature amount FQi of a part or all of the region around the region of interest may also be taken into consideration.
For example, the light source control value LS10 of one region of FIG. 2, for example, the region A10, is not only the region A10 but also the regions A1, the region A2, the region A3, the region A9, the region A11, the region A17, the region A18, and the regions adjacent to the region A10. It may be calculated by weighting and adding the feature amount of the area A19.

In the above weighting addition, each feature amount in the surrounding area may be weighted according to the distance from the area of interest A10. For example, a region closer to the region of interest A10 (for example, a distance between the centers of the regions) may be given a larger weight to the feature amount of the region.
As the peripheral region, not only an adjacent region as in the above example but also a region within a wider range may be used. For example, 5 × 5 regions may be used centering on the region of interest.

The average value calculation unit 103 calculates the average value LSave of the light source control value LSi (i = 1 to 72) in each region.

The correction intensity calculation unit 104 calculates the correction intensity G from the average light source control value LSave. The correction strength G is calculated by the following equations (1) and (2).
G = 1 / LSave ... Equation (1)
However, G ≤ 2 ... Equation (2)

According to the above equation (2), G is limited to 2 or less, and G = 2 when LSave is 0.5 or less.

FIG. 4 shows the relationship between LSave and G according to the above equations (1) and (2).

When the light source control value LSi is represented by a value in the range of 0 to 1, the maximum value of the average light source control value LSave (the maximum value within the range of possible values) is 1. When the light source control value LSi is represented by an 8-bit value, the average light source control value LSave is also represented by an 8-bit value, and the maximum value is 255. In that case, the following formula (1a) is used instead of the formula (1).
G = 255 / LSave ... Equation (1a)

Further, in digital data processing, the correction strength G is also represented by an 8-bit value, and when the correction strength G represented by the formula (1) or the formula (1a) is 1, the 8-bit value representing the correction strength G is 128. This may facilitate processing. In that case, the following formula (1b) is used instead of the formula (1) or the formula (1a).
G = 128 × 255 / LSave ... Equation (1b)

The comparison unit 105 compares the light source control value LSi of each region with the average light source control value LSave, and outputs the comparison value Ci for the region showing the result of the comparison. The comparative value Ci is obtained by, for example, the following equations (3) and (4).
Ci = LSi-LSave ... Equation (3)
However, when LSi <LSave, Ci = 0 ... Equation (4)
FIG. 5 shows the relationship between LSi-LSave and Ci according to the above equations (3) and (4).

The light source control value correction unit 106 corrects the light source control value (first light source control value) LSi in the region based on the correction intensity G, the comparison value Ci for each region, and the average light source control value LSave. , The corrected light source control value (second light source control value) LSCi for the relevant region is output. The calculation for correction is expressed by the following equations (5) and (6).
LSSi = Ci × G + LSave… Equation (5)
However, when Ci = 0, LSCi = LSi ... Equation (6)

The relationship between LSCi and LSi obtained by the above equations (5) and (6) is shown in FIG. 6 with LSave as a parameter. That is, in FIG. 6, when the value of LSave is 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8. The relationship between LSCi and LSi is shown for each of the cases of and 1.0.

In the above example, equations (4) and (6) are defined as constraints on equations (3) and (5). However, the equation (5) is applied in the case of LSi ≧ LSave, and in the case of LSi <LSave, LSCi = LSi, that is, it is not corrected.

Therefore, the comparison unit 105 outputs the comparison result of LSi <LSave instead of setting Ci = 0 in the case of LSi <LSave, and the light source control value correction unit 106 outputs the comparison result in the case of LSi <LSave. = LSi may be used.

If LSave is an 8-bit value, LSCi may exceed 255, as can be seen from the equation (5). Therefore, it is better to configure LSCi to be represented by a value of 9 bits or more. In the following, it is assumed to be represented by a 9-bit value. In this case, in order to make the comparison with LSi easy to understand, here, it is assumed that the 9-bit value 255 corresponds to 1, and the value larger than 255 corresponds to the value larger than 1.

When the light source control value is corrected as described above, how the corrected light source control value LSCi changes depending on the content of the image will be described with reference to FIG. 7.
In FIG. 7, the light source control value LSi in each region is assumed to be equal to the average value of the brightness in the region. Further, in FIG. 7, it is assumed that LSi and LSave take a value from 0 to 1. Further, in the column of Ci in FIG. 7, the values enclosed in parentheses are values obtained by the calculation of the equation (3) and not adopted by the proviso of the equation (4). Similarly, in the column of LSCi, the values enclosed in parentheses are the values obtained by the calculation of the equation (5) and not adopted by the proviso of the equation (6).

In an all-white image (an image in which the whole is white), the light source control value LSi in each region is a maximum value of 1 (255 for an 8-bit value), and the corrected light source control value LSSi is also a value equal to the above maximum value 1. The 9-bit value is 255).
In the case of an all-gray image (an image in which the luminance value is an intermediate value of 0.5 (128 for an 8-bit value) for all pixels), the light source control value LSi for each region is 0.5 (128 for an 8-bit value), which is corrected. The light source control value LSCi is also 0.5 (128 with a 9-bit value).

Further, one half (for example, the left half) is black, that is, the brightness value is the minimum value 0 (even an 8-bit value is 0), and the other half (for example, the right half) is white, that is, the brightness value is the maximum value 1 (8). In the image with a bit value of 255), the light source control value LSi in each region of the left half is 0 (0 even with an 8-bit value), the correction light source control value LSCi is also 0 (0 even with a 9-bit value), and the right half. The light source control value LSi in each region is 1.0 (255 with an 8-bit value), while the correction light source control value LSCi is 1.5 (about 384 with a 9-bit value).

In this way, the correction light source control value LSSi is suppressed to be lower in the all-gray image than in the case of the all-white image. Further, in an image in which the left half is black and the right half is white, which has the same average light source control value LSave as the all gray image, the correction light source control value LSCi is higher for the right half than in the case of the all white image.

In FIG. 8, the backlight 400 has seven regions Aa to Ag (unlike the example of FIG. 2), the luminance values of all the pixels in each region are equal to each other, and the average luminance values between the regions are equal to each other. When they are different from each other, the light source control value LSi and the corrected light source control value LSCi in each region are shown. Also in FIG. 8, it is assumed that LSi and LSave take a value from 0 to 1. Further, also in FIG. 8, the light source control value LSi in each region is assumed to be equal to the average value of the brightness in the region. Further, also in FIG. 8, the values enclosed in parentheses in the Ci column are the values obtained by the calculation of the equation (3) and not adopted by the proviso of the equation (4), and are enclosed in parentheses in the LSCi column. The obtained value is a value obtained by the calculation of the equation (5) and is not adopted by the proviso of the equation (6).

As can be seen from FIG. 8, in the region where the average luminance value is equal to or less than the average luminance value of the entire image (the region where the light source control value LSi is equal to or less than the average light source control value LSave), the correction light source is used in Ad, Ae, Af, and Ag. The control value LSCi is equal to the light source control value LSi. On the other hand, in the region where the average brightness value is larger than the average value of the brightness of the entire image (the region where the light source control value LSi is larger than the average light source control value LSave) Aa, Ab, and Ac, the corrected light source control value LSSi is the light source control. It is larger than the value LSi, and the ratio of the increase of the correction light source control value LSCi to the increase of the light source control value LSi is 2, that is, equal to the correction intensity G.

The relationship between the light source control value LSi and the correction light source control value LSCi shown in FIG. 8 is the same as the relationship shown by the curve when LSave is 0.5 in FIG.

As described above, the image signal processing unit 200 performs signal processing on the input image signal Da based on the light source control value LSi in each region. This signal processing includes gradation correction.
In this gradation correction, for example, in the region where the light source control value LSi is large, the gradation value of the image signal becomes small, and in the region where the light source control value LSi is small, the gradation value of the image signal is controlled to be large. It will be done. A small gradation value of an image signal means that the image is dark, and a large gradation value of an image signal means that the image is bright.

In the region where the light source control value LSi is large, it may be possible not to perform processing that makes the image dark. That is, processing may be performed so that the image becomes brighter in any region or the same brightness is maintained.

In order to prevent deterioration of image quality (giving the viewer a sense of discomfort) due to discontinuity or sudden change in image signal processing at the boundary between regions, the boundary is adjacent to the light source control value of each region. The control may be performed based on the mixed value with the light source control value in the region to be controlled.

Further, the brightness of each of the light sources constituting the backlight 400 tends to gradually decrease as the distance from the center thereof increases, and the overall brightness distribution of the backlight 400 composed of a plurality of light sources is not always uniform. Taking these points into consideration, for example, in a place where the brightness is low, an additional process such as increasing the light source control value by correction may be performed.

In the above image display device, when an image including a dark part is input, the backlight is darkened in the dark part as compared with the case where an all-white image is input, thereby suppressing power consumption (energy saving). Can be planned). Further, since the gradation value of the image signal is increased in the portion where the backlight is darkened, the brightness of the displayed image is the same as when the backlight is not darkened and the image signal is not corrected. Become. Further, in a partially bright image, the bright part is displayed sufficiently bright (equal to or better than the case where the backlight is not dimmed and the image signal is not corrected). Therefore, it is possible to display a high-contrast image.

In the above example, the upper limit value of the correction strength G is 2, but the upper limit value of the correction strength G may be a value other than 2. If generalized, the correction strength G may be limited to an arbitrary set value M (M is a value larger than 1) or less.

By limiting the correction intensity G to the set value M or less, it is possible to adjust so that the correction of the emission brightness does not become too strong.
For example, when the average light source control value LSave is small, that is, when the image is dark as a whole (when the gradation value of the image signal is small), the correction of the emission luminance can be adjusted so as not to be too strong. In particular, for example, a strong correction may be applied according to the user's preference, usage conditions, etc., but it can be adjusted so that the correction does not become too strong when the image is dark as a whole.

The upper limit of the correction intensity G can be determined based on the driving method of the light source controlled by the light source control device 100. For example, when normal driving (driving when the light source control value is not corrected) is performed with 1/2 or less of the capacity of each of the drive circuits constituting the light source driving device 402, the upper limit value of the correction intensity G should be set to 2. For example, the correction light source control value LSCi does not become a value that exceeds the capacity of each drive circuit (a value that requires driving with a capacity that exceeds the capacity of the drive circuit).

Embodiment 2.
FIG. 9 shows a light source control device according to the second embodiment. The light source control device 100b shown in FIG. 9 is generally the same as the light source control device 100 of FIG. However, instead of the correction intensity calculation unit 104 and the light source control value correction unit 106 in FIG. 3, a correction intensity calculation unit 104b and a light source control value correction unit 106b are provided.

The correction strength calculation unit 104b calculates the correction strength G by the following formula (7).
G = 1 / LSave + 1 ... Equation (7)

The calculation of the comparison value Ci in the comparison unit 105 is the same as that in the first embodiment.

The light source control value correction unit 106b calculates the correction light source control value LSCi by the above equations (5) and (6) in the same manner as the light source control value correction unit 106 of FIG.
However, when the corrected light source control value LSSi calculated by the equations (5) and (6) exceeds twice the maximum value LSmax of the light source control value, twice the LSmax is defined as LSSi. That is, the restriction of the following equation (8) is set for LSCi.
LSSi ≦ 2 × LSmax… Equation (8)
The maximum value LSmax of the light source control value is the light source control value of the region when all the pixels in one region are white pixels.
Here, the white pixel means a pixel having a maximum brightness or brightness (the largest value within the range of possible values, for example, 255 for an 8-bit value).

Note that the limitation by equation (8) can be realized in digital data processing by expressing LSCi with a value with a bit number that is one more than LSi and clipping at the maximum value. For example, if LSi is an 8-bit value, LSCi is set to a 9-bit value, and the limitation by the equation (8) can be realized by clipping to the maximum value 511.

In the second embodiment, by calculating the corrected light source control value as described above, the correction for the light source control value can be strengthened as compared with the first embodiment, and the following conditions (a1) and (b) can be strengthened. The light source control value is corrected so as to satisfy the above conditions.
(A1) No matter what image is input, the average value (or total value) of the correction light source control value LSCi is driven by the power consumption exceeding the power consumption of the entire backlight when the all-white image is input. Does not require.
(B) The corrected light source control value LSSi in each region does not exceed twice the maximum value LSmax of the light source control value.

Regarding the above condition (a1), the corrected light source control value LSSi when the all-white image is input is equal to the maximum value LSmax of the light source control value, like the light source control value LSi.
The above conditions (a1) and (b) are necessary from, for example, the capacity of the power supply for driving all the light sources of the backlight, the capacity of each of the plurality of light sources (rated values, etc.), the driving method of the light sources, and the like. Will be done.

The capacity of the power supply to drive all the light sources of the backlight is limited by, for example, the cost of the image display device including the backlight. No matter what the input image is, it is necessary to ensure that the sum of the corrected light source control values over the entire backlight does not require driving with a capacity larger than the capacity of the power supply.

Generally, the light source control value LSi when the all-white image is input is determined to match the capacity of the power supply. As described above, the light source control value LSi when the all-white image is input and the corrected light source control value LSSi are equal to the maximum value LSmax of the light source control value. Therefore, the light source control value corresponding to the power consumption by the entire backlight when the all-white image is input corresponds to the maximum value LSmax of the light source control value. From the above, the above condition (a1) can be paraphrased as the following condition (a2).
(A2) No matter what kind of image is input, the average value LS Save over the entire backlight of the corrected light source control value LSSi does not exceed the maximum value LSmax of the light source control value.

Further, in the second embodiment, when the all-white image is input, the capacity (rated value, etc.) of each light source is halved, and each drive circuit (a plurality of drive circuits constituting the light source drive device 402) is used. ) Is to be driven by 1/2 of the capacity. Then, if the above condition (b) is satisfied, driving with a capacity exceeding the capacity of each light source and the capacity of each drive circuit is not required. Therefore, the above condition (b) is imposed on the calculation of the corrected light source control value LSSi.

Further, in the present embodiment, the correction of the light source control value is made as strong as possible. That is, the following condition (c) is satisfied.
(C) Increase the degree of correction for the light source control value as much as possible. That is, the correction light source control value LSSi is made as large as possible as a whole.

The reason why the above conditions (a2), (b) and (c) are satisfied by performing the processing as described above in the correction intensity calculation unit 104b and the light source control value correction unit 106b will be described below.

First, the reason why the above conditions (a2) and (c) are satisfied by using the equation (7) for calculating the correction strength G will be described. However, here, it is premised that the operation of the comparison unit 105 and the light source control value correction unit 106b is the same as the operation of the comparison unit 105 and the light source control value correction unit 106 in the first embodiment.

Regarding the above condition (a2), the average value of the corrected light source control values becomes the largest when the following condition (d) is satisfied.
(D) The backlight 400 includes a region where the light source control value LSi is the maximum value LSmax and a region where the light source control value LSi is 0.

Regarding the above condition (d), the ratio of the region where the light source control value LSi is the maximum value LSmax is Rm, and the ratio of the region where the light source control value LSi is 0 is Ro.
The above ratios Rm and Ro mean the ratio of the total area of the corresponding area to the total area of the area of the backlight 400. Assuming that the areas of the respective regions are equal to each other, the above ratios Rm and Ro are equal to Im / I and Io / I, respectively. Here, I represents the total number of regions, Im represents the number of regions where the light source control value LSi is the maximum value LSmax, and Io represents the number of regions where the light source control value LSi is 0.
There is a relationship expressed by the following equation (9) between the above ratio Rm and the average value LSave of the light source control value and the maximum value LSmax of the light source control value.
There is a relationship represented by the following equation (10) between the above ratio Ro and the average value LSave of the light source control value and the maximum value LSmax of the light source control value.
Rm = LSave / LSmax ... Equation (9)
Ro = (LSmax-LSave) / LSmax ... Equation (10)

FIG. 10 shows an example of a combination of regions satisfying the above condition (d). FIG. 10 is an example of the light source control values before correction in the 72 regions A1 to A72 similar to those shown in FIG. The numerical values in the figure are light source control values in each region.
In FIG. 10, the number of regions where the light source control value LSi is the maximum value LSmax is 45, and the number of regions where the light source control value LSi is 0 is 27, which is Rm = Im / I = 45. It can be said that the case of / 72 is assumed.

In FIG. 10, the region where the light source control value LSi is the maximum value LSmax is concentrated in the five columns on the right side, and the region where the light source control value LSi is 0 is concentrated in the three columns on the left side. In other words, the region where the light source control value LSi is the maximum value LSmax forms one block, and the region where the light source control value LSi is 0 forms another block. However, this point has no particular significance, and for example, as shown in FIG. 11, a region in which the light source control value LSi is the maximum value LSmax and a region in which the light source control value LSi is 0 may be mixed.

The corrected light source control value LSCm in the region where the light source control value LSi is the maximum value LSmax is given by the following equation (11) from the equations (3) and (5).
LSCm
= ((LSmax-LSave) × G + LSave)… Equation (11)

The average value LS Save over the entire backlight 400 of the corrected light source control value LSCi is as shown in the following equation (12) from the equations (9) and (11).
LS Save
= ((LSmax-LSave) x G + LSave) x LSave / LSmax
… Equation (12)

The condition that the average value LS Save of the corrected light source control value becomes equal to the maximum value LSmax of the light source control value is expressed by the following equation (13).
((LSmax-LSave) x G + LSave) x LSave / LSmax
= LSmax
… Equation (13)

When the equation (13) is modified, it becomes as follows.
(LSmax-LSave) x G + LSave = (LSmax ² / LSave)
… Equation (14)
G = (LSmax ² / LSave-LSave) / (LSmax-LSave)
… Equation (15)
G = (LSmax ^2- LSave ² ) / ((LSmax-LSave) × LSave)
… Equation (16)
G = (LSmax + LSave) / LSave ... Equation (17)
G = LSmax / LSave + 1 ... Equation (18)

If LSmax is 1 in equation (18), it matches equation (7).

By substituting G in the equation (7) into the equation (12), the following equation (19) is obtained.
LS Save
= ((LSmax-LSave) × (1 / LSave + 1) + LSave) × LSave / LSmax
… Expression (19)

When LSmax = 1 is set in the formula (19) and arranged, the following formula (20) is obtained.
LS Save
= ((1-LSave) x (1 + LSave) + LSave ² / LSave) x LSave
= 1-LSave ² + LSave ²
= 1 ... Equation (20)

Equation (20) shows that the average correction light source control value LS Save maintains 1 regardless of whether Rm = Im / I = LSave / LSmax.

This is done by using the correction intensity G calculated based on the equation (7) and calculating the correction light source control value LSCi using the equations (3), (4), (5), and (6). The power consumption when the average value of the corrected light source control values is the largest (when the condition (d) is satisfied, that is, when the power consumption is the largest) is the same as the power consumption when the all-white image is input. Means that.
Further, if the correction light source control value is calculated by using the correction intensity G calculated based on the equation (7) and using the equations (3), (4), (5), and (6), the correction light source is used. The power consumption required by the control value does not become larger than the power consumption when the all-white image is input.

As described above, the correction is performed as much as possible by determining the correction intensity by the equation (7) and determining the correction light source control value by using the equations (3), (4), (5), and (6). It can be strengthened (the corrected light source control value in each area is made as large as possible), and the average value LS Save of the corrected light source control value is larger than the average value LS Save of the light source control value when the all-white image is input. There is no. That is, the above condition (a2) and condition (c) can be satisfied.
The above is the reason why the equation (7) is used for calculating the correction strength G.

However, when the correction intensity G is determined as described above, the correction light source control value LSCi in each region becomes too large, and is larger than twice the light source control value when all the pixels in the corresponding region are white pixels. May be. Therefore, as shown in the equation (8), an upper limit is set for the correction light source control value.
The above is the reason for limiting the equation (8).

The calculation of the corrected light source control value LSCi is limited by the equation (8), but the corrected light source control value LSCi is set to the largest value within the range of the limit. Therefore, it can be said that the correction light source control value is set as large as possible within the constraint of the equation (8).

As in the first embodiment, the correction intensity G may be limited to an arbitrary set value M or less, and further adjustment may be made so that the correction of the emission brightness is not too strong.

Since equations (3) and (5) are used to calculate the corrected light source control value LSSi, when the light source control value takes a value other than 0 or LSmax, the average value LSave of the light source control values and each region. The difference between the light source control values, that is, the value calculated by the equation (3) is relatively small, and therefore the average value of the corrected light source control values is smaller than when an image satisfying the above condition (d) is input. .. Therefore, the power consumption is smaller than the power consumption when the all-white image is input.

As described above, if the correction intensity G is calculated based on the equation (7) and the correction light source control value is calculated using the equations (3), (4), (5), (6) and (8). , The power consumption required by the correction light source control value does not become larger than the power consumption when the all-white image is input, and it is possible to control the backlight 400 to emit light with the maximum brightness. Is.

Embodiment 3.
FIG. 12 shows the configuration of the image display device according to the third embodiment. The image display device shown in FIG. 12 is generally the same as the image display device described with reference to FIG. 1 with respect to the first embodiment. However, the light source control device 100c is provided instead of the light source control device 100, and the image signal processing unit 200c is provided instead of the image signal processing unit 200.

FIG. 13 shows the configuration of the light source control device 100c. The light source control device 100c shown in FIG. 13 is generally the same as the light source control device 100 shown in FIG. However, the light source control value LSi output from the light source control value calculation unit 102 is not output to the outside of the light source control device 100c, and instead, the correction light source control value LSCi output from the light source control value correction unit 106 is an image. It is supplied to the signal processing unit 200c.

The content of the processing in the light source control device 100c is the same as that described with respect to the light source control device 100 in the first embodiment.

In the image display device shown in FIG. 12, the image signal processing unit 200c performs signal processing on the input image signal Da based on the correction light source control value LSCi of each region input from the light source control device 100c.

The same effect as that of the first embodiment can be obtained in the third embodiment. In the third embodiment, the following effects can be further obtained.
The corrected light source control value LSSi may be larger than the maximum value LSmax of the light source control value.
In the image signal processing unit 200c, the corrected light source control value LSCi is the maximum value of the light source control value in the region where the corrected light source control value LSCi exceeds the maximum value LSmax of the light source control value in the entire area constituting the backlight 400. It is possible to perform signal processing different from the region that does not exceed LSmax. For example, in the region where the corrected light source control value LSCi exceeds the maximum value LSmax of the light source control value, the signal processing intensity is changed by the difference in the light source control value from the region where the maximum value LSmax of the peripheral light source control value is not exceeded. .. Therefore, signal processing can be continuously optimized in the region where the corrected light source control value LSCi exceeds the maximum value LSmax of the light source control value and the region where the corrected light source control value LSCi does not exceed the maximum value LSmax of the light source control value. , The displayed image can be made to look more natural.

Embodiment 4.
FIG. 14 shows the configuration of the image display device according to the fourth embodiment. The image display device shown in FIG. 14 is generally the same as the image display device described with reference to FIG. 1 with respect to the first embodiment. However, the light source control device 100d is provided in place of the light source control device 100, and the image signal processing unit 200d is provided in place of the image signal processing unit 200.

The image signal processing unit 200d has the same internal configuration as the image signal processing unit 200, but outputs the average gradation value APL of the input image signal Da. The average gradation value APL is an average value of the brightness, brightness, etc. of the input image signal Da, and is calculated in the image signal processing unit 200d. The average gradation value APL is supplied to the light source control device 100d.

FIG. 15 shows the configuration of the light source control device 100d. The light source control device 100d shown in FIG. 15 is generally the same as the light source control device 100 shown in FIG. However, the average value calculation unit 103 is not provided, and instead of the correction intensity calculation unit 104, the comparison unit 105, and the light source control value correction unit 106, the correction intensity calculation unit 104d, the comparison unit 105d, and the light source control value correction unit are used. A portion 106d is provided.

The correction intensity calculation unit 104d calculates the correction intensity G by using the average gradation value APL instead of the average light source control value LSave.
That is, the correction strength G is determined by the following equations (21) and (22).
G = 1 / APL ... Equation (21)
However, G ≤ 2 ... Equation (22)

The comparison unit 105d makes a comparison using the average gradation value APL instead of the average light source control value LSave. That is, the comparison unit 105d compares the light source control value LSi of each region calculated by the light source control value calculation unit 102 with the average gradation value APL, and outputs a comparison value Ci indicating the comparison result.

That is, the comparison value Ci is obtained by, for example, the following equations (23) and (24).
Ci = LSi-APL ... Equation (23)
However, when LSi <APL, Ci = 0 ... Equation (24)

The light source control value correction unit 106d is a light source control value calculation unit 102 based on the comparison value Ci output from the comparison unit 105d, the correction intensity G calculated by the correction intensity calculation unit 104d, and the average gradation value APL. The calculated light source control value LSi of each region is corrected, and the corrected light source control value LSCi is output.
The following equations (25) and (26) are used to generate the corrected light source control value LSSi.
LSSi = Ci × G + APL… Equation (25)
However, when Ci = 0, LSCi = LSi ... Equation (26)

The same effect as that of the first embodiment can be obtained in the fourth embodiment. In the fourth embodiment, the effects described below can be further obtained.

The average gradation value APL is a value equal to or less than the average light source control value LSave calculated by the average value calculation unit 103 described with reference to FIG. 3 in the first embodiment.
The light source control value calculation unit 102 uses, for example, a peak value or an average value such as brightness and brightness of each region, or a mixed value of the peak value and the average value as the light source control value LSi. However, it is not smaller than the average gradation value APL.
That is, when the peak value of luminance or brightness is the light source control value LSi, the average gradation value APL is equal to or smaller than the average light source control value LSave.
When the average value of brightness or brightness is the light source control value LSi, the average gradation value APL is equal to the average light source control value LSave.
Even when the mixed value of the peak value of luminance or brightness and the average value is set as the light source control value LSi, the average gradation value APL is equal to or smaller than the average light source control value LSave.

Therefore, in the light source control device 100d of FIG. 15, as can be seen from the comparison between the equations (1) and (2) and the equations (21) and (22), the correction intensity G is the figure with respect to the first embodiment. The value is equal to or greater than the correction intensity G calculated by the light source control device of 3.

In other words, the correction intensity G when the average gradation value APL is used is not smaller than the correction intensity G when the average light source control value LSave is used, and the correction light source control value when the average gradation value APL is used. However, it is not smaller than the corrected light source control value when the average light source control value LSave is used.
Therefore, the backlight 400 is controlled to emit brighter light as a whole, and the desired result can be obtained, for example, in an environment where higher brightness is required.

Embodiment 5.
FIG. 16 shows the configuration of the image display device according to the fifth embodiment. The image display device shown in FIG. 16 is generally the same as the image display device described with reference to FIG. 14 with respect to the fourth embodiment. However, the light source control device 100e is provided in place of the light source control device 100d, and the image signal processing unit 200e is provided in place of the image signal processing unit 200d.

FIG. 17 shows the configuration of the light source control device 100e. The light source control device 100e shown in FIG. 17 is generally the same as the light source control device 100d shown in FIG. However, the light source control value LSi output from the light source control value calculation unit 102 is not output to the outside of the light source control device 100e, and instead, the corrected light source control value LSCi output from the light source control value correction unit 106d is an image. It is supplied to the signal processing unit 200e.

The content of the processing in the light source control device 100e is the same as that described with respect to the light source control device 100d in the fourth embodiment.

The image signal processing unit 200e outputs the average gradation value APL to the light source control device 100e, as in the image signal processing unit 200d of the fourth embodiment.

In the image display device shown in FIG. 16, the image signal processing unit 200e performs signal processing on the input image signal Da based on the corrected light source control value LSCi of each region input from the light source control device 100e.
The content of the signal processing in the image signal processing unit 200e is the same as that described with respect to the image signal processing unit 200c in the third embodiment.

In the fifth embodiment, since the average gradation value APL is used for the calculation of the correction intensity in the correction intensity calculation unit 104d and the comparison with the light source control value in the comparison unit 105d, the same effect as that of the fourth embodiment can be obtained. ..
Further, since the image signal processing unit 200e performs signal processing on the image signal using the corrected light source control value LSSi, the same effect as that of the third embodiment can be obtained.

In the first to third embodiments, the average light source control value LSave is used for the calculation of the correction intensity G in the correction intensity calculation unit, the calculation of the comparison value Ci in the comparison unit, and the calculation of the correction light source control value LSCi in the light source control value correction unit. It is used, and in the fourth and fifth embodiments, the average gradation value APL is used.
The average light source control value LSave and the average gradation value APL are common in that they are brightness indexes of the input image. Therefore, in all of the first to fifth embodiments, the input image is used for the calculation of the correction intensity G in the correction intensity calculation unit, the calculation of the comparison value Ci in the comparison unit, and the calculation of the correction light source control value LSCi in the light source control value correction unit. It can be said that the brightness index of is used.

Each of the light source control devices 100, 100b, 100c, 100d, and 100e described in the first to fifth embodiments may be partially or wholly composed of a processing circuit.
For example, the functions of each part of the light source control device may be realized by separate processing circuits, or the functions of a plurality of parts may be collectively realized by one processing circuit.
The processing circuit may be composed of hardware or software, that is, a programmed computer.
Of the functions of each part of the display control device, a part may be realized by hardware and the other part may be realized by software.

FIG. 18 shows an example of a configuration in which the function of the light source control device 100 of the first embodiment is realized by a computer 900 including a single processor, together with an image signal processing unit 200, a display panel 300, and a backlight 400. show.

In the illustrated example, the computer 900 has a processor 910 and a memory 920.
The memory 920 stores a program for realizing the functions of each part of the display control device.

The processor 910 uses, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a microprocessor, a microprocessor, a DSP (Digital Signal Processor), or the like.
The memory 920 may be, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Memory Disk Memory), an EEPROM (Electrically Memory, etc.), or an EEPROM. Alternatively, a photomagnetic disk or the like is used.

The processor 910 and the memory 920 may be realized by an LSI (Large Scale Integration) integrated with each other.

The processor 910 realizes the function of the light source control device by executing the program stored in the memory 920.
The function of the light source control device includes the control of the brightness of the backlight 400 as described above.
The program may be provided through a network, or may be recorded and provided on a recording medium, such as a non-temporary recording medium. That is, the program may be provided, for example, as a program product.

A processing procedure in the case of performing the same light source control as that of the light source control device of the first embodiment on the computer shown in FIG. 18 will be described with reference to FIG.

The process shown in FIG. 19 is repeated every time one frame of image signal is input. That is, it is repeatedly performed for the time-series input of the image signal.

In step ST10, one frame of image signal Da is received.
In step ST11, the feature amount FQi is calculated for the input image signal. This process corresponds to the process in the feature amount calculation unit 101 of FIG.
In step ST12, the light source control value LSi of each region of the backlight 400 is calculated. This process corresponds to the process in the light source control value calculation unit 102 of FIG.

In step ST13, the average light source control value LSave is calculated from the light source control value LSi in all regions of the backlight 400. This process corresponds to the process in the average value calculation unit 103 of FIG.

In step ST14, the correction intensity G is calculated from the average light source control value LSave. This process corresponds to the process in the correction strength calculation unit 104 of FIG.
In step ST15, the comparison value Ci of the region is calculated from the light source control value LSi of each region and the average light source control value LSave. This process corresponds to the process in the comparison unit 105 of FIG.
The processing of step ST14 and the processing of step ST15 can be performed in parallel.

In step ST16, the correction light source control value LSSi of the region is calculated from the correction intensity G, the comparison value Ci of each region, and the average light source control value LSave. This process corresponds to the process in the light source control value correction unit 106 of FIG.

In step ST17, it is determined whether or not the processing should be continued.
When the input of the image signal Da continues, that is, when the image signal of the next frame is input and there is no particular need to end, it is determined that the continuation should be performed, and the process returns to step ST10.
If not, the process ends.

Although the case where the light source control device of the first embodiment is realized by the computer has been described above, the procedure of the configuration and the processing when the light source control device of the second to fifth embodiments is realized by the computer is also described in the first embodiment. Same as the case.

For example, when the same computer as shown in FIG. 18 performs the same light source control as the light source control device of the fourth embodiment, the process may be performed by the procedure shown in FIG. 20, for example.

The process shown in FIG. 20 is generally the same as the process shown in FIG. However, step ST13 is not provided, and steps ST14, ST15, and ST16 are replaced with steps ST14d, ST15d, and ST16d.

In step ST14d, the correction intensity G is calculated from the average gradation value APL. This process corresponds to the process in the correction strength calculation unit 104d of FIG.
In step ST15d, the comparison value Ci of the region is calculated from the light source control value LSi of each region and the average gradation value APL. This process corresponds to the process in the comparison unit 105d of FIG.
In step ST16d, the correction light source control value LSCi in the region is calculated from the correction intensity G, the comparison value Ci in each region, and the average gradation value APL. This process corresponds to the process in the light source control value correction unit 106d of FIG.

Various modifications are possible to the above embodiment.
For example, although the second embodiment has been described as a modification to the first embodiment, similar modifications can be added to the third to fifth embodiments.

Although the light source control device has been described above, it is also possible to implement the light source control method by using the light source control device, and it is also possible to have a computer execute the processing in the light source control device or the light source control method by a program. ..

1 Image input terminal, 100, 100b, 100c, 100d, 100e Light source control device, 101 feature amount calculation unit, 102 light source control value calculation unit, 103 average value calculation unit, 104, 104b, 104d correction strength calculation unit, 105, 105d Comparison unit, 106, 106d light source control value correction unit, 200, 200c, 200d, 200e image signal processing unit, 300 display panel, 400 backlight, 402 light source drive device, 900 computer, 910 processor, 920 memory.

Claims (15)

1. In a light source control device that controls a backlight that can control brightness in multiple areas
   A feature amount calculation unit that calculates a feature amount indicating the brightness or brightness of an image for each of the regions from an input image signal, and a feature amount calculation unit.
   A light source control value calculation unit that calculates a light source control value for each region of the backlight based on the feature amount of the region, and a light source control value calculation unit.
   A comparison unit that compares the light source control value for each region with the brightness index of the input image signal and outputs the comparison result for the region.
   A correction strength calculation unit that calculates the correction strength from the brightness index,
   It is provided with a light source control value correction unit that generates a correction light source control value for the region from the comparison result for each region and the correction intensity.
   The light source control value of each region calculated by the light source control value calculation unit is larger as the brightness or brightness of the image represented by the feature amount for the region is larger.
   The correction strength calculated by the correction strength calculation unit is larger as the brightness index is smaller.
   The light source control value correction unit is
   When the comparison unit determines that the light source control value is larger than the brightness index, the brightness is obtained by multiplying the value obtained by subtracting the brightness index from the light source control value in the region by the correction intensity. The value obtained by adding the index is output as the correction light source control value.
   When the comparison unit determines that the light source control value in each region is equal to or less than the brightness index, the light source control device outputs the light source control value in the region as the corrected light source control value in the region. ..
2. The light source control device according to claim 1, wherein the feature amount in each region is a peak value or an average value of brightness or brightness in the region, or a value calculated from the peak value and the average value.
3. The light source control device according to claim 1 or 2, wherein the light source control value of each region is calculated based on the feature amount of the region and the region around the region.
4. The light source control device according to any one of claims 1 to 3, wherein the correction intensity calculation unit calculates the reciprocal of the brightness index as the correction intensity.
5. The light source control device according to any one of claims 1 to 3, wherein the correction intensity calculation unit calculates a value obtained by adding 1 to the reciprocal of the brightness index as the correction intensity.
6. The light source control device according to claim 5, wherein the light source control value correction unit limits the corrected light source control value so as not to exceed twice the maximum value of the light source control value.
7. Further, it has an average value calculation unit for calculating the average value of the light source control value in the region over the entire backlight as the average light source control value.
   The light source control device according to any one of claims 1 to 6, wherein the average light source control value is used as the brightness index.
8. The light source control device according to any one of claims 1 to 6, wherein the average gradation value of the input image signal is used as the brightness index.
9. The light source control device according to any one of claims 1 to 8, wherein the average value of the corrected light source control values does not exceed the maximum value of the light source control value.
10. The light source control device according to any one of claims 1 to 9, wherein the correction intensity calculation unit limits the correction intensity to a set value or less.
11. The light source control device according to any one of claims 1 to 10.
    An image signal processing unit that generates a corrected image signal by gradation-correcting the input image signal based on the light source control value or the corrected light source control value in each region output by the light source control device.
    A display panel in which the transmittance is controlled for each pixel according to the corrected image signal generated by the image signal processing unit.
    Equipped with the backlight
    In the backlight, an image display device in which the brightness of the region is controlled based on the corrected light source control value of each region output by the light source control device.
12. The light source control device according to claim 8 and
    An image signal processing unit that generates a corrected image signal by gradation-correcting the input image signal based on the light source control value or the corrected light source control value in each region output by the light source control device.
    A display panel in which the transmittance is controlled for each pixel according to the corrected image signal generated by the image signal processing unit.
    Equipped with the backlight
    In the backlight, the brightness of the region is controlled based on the corrected light source control value of each region output by the light source control device.
    The image signal processing unit is an image display device that calculates and outputs the average gradation value based on the input image signal.
13. In the light source control method that controls the backlight that can control the brightness in multiple areas,
    From the input image signal, a feature amount indicating the brightness or brightness of the image is calculated for each of the regions.
    The light source control value for each region of the backlight is calculated based on the feature amount of the region.
    The light source control value for each region is compared with the brightness index of the input image signal, and the comparison result for the region is output.
    The correction intensity is calculated from the brightness index, and the correction intensity is calculated.
    A correction light source control value for the region is generated from the comparison result for each region and the correction intensity.
    The light source control value in each region increases as the brightness or brightness of the image represented by the feature amount for the region increases.
    The correction intensity increases as the brightness index becomes smaller.
    When the light source control value is larger than the brightness index, the value obtained by subtracting the brightness index from the light source control value in the region multiplied by the correction intensity and adding the brightness index is used. Use as the correction light source control value
    A light source control method in which when the light source control value in each region is equal to or less than the brightness index, the light source control value in the region is used as the corrected light source control value in the region.
14. A program for causing a computer to execute the process in the light source control method according to claim 13.
15. A computer-readable recording medium on which the program according to claim 14 is recorded.

Images