JP5382317B2 - Display device, program, and information storage medium - Google Patents

Description

  The present invention relates to a display device, a program, and an information storage medium.

  The display device can improve the contrast of the displayed image by performing dimming and luminance expansion according to the luminance of the input image. For example, in Japanese Patent Application Laid-Open No. 2005-257761, image parameter extracting means for extracting image parameters characterizing the brightness of a display image per unit time from an image signal, and dimming control related to dimming processing based on the image parameters are disclosed. A light control unit for determining a parameter and performing a light control process based on the light control parameter, and determining an expansion control parameter for the expansion process based on the image parameter extracted by the image parameter extraction unit, Expansion processing means for performing expansion processing based on the expansion control parameter, and the expansion processing means expands so that the maximum gradation of the input image signal is lower than the maximum output gradation after the expansion processing. An image display device that determines control parameters and performs expansion processing is described.

Japanese Patent Laid-Open No. 2005-257761

  However, when the extension process becomes excessive, the luminance value is saturated, and so-called overexposure (brightness flattening in a high gradation portion) may occur. For example, when a whiteout occurs in a wide range like a cloud in the sky, it becomes a big problem.

  An object of the present invention is to provide a display device, a program, and an information storage medium that can more appropriately prevent the occurrence of unintended luminance flattening when performing luminance expansion.

  In order to solve the above-described problem, a display device according to the present invention includes a feature information generation unit that generates feature information indicating a plurality of types of features related to the brightness of an image based on an image signal, and a luminance expansion according to an adjustment value. A luminance expansion unit that performs expansion of the expansion coefficient generation unit that generates an expansion coefficient based on at least a part of the feature information, and a plurality of pixels included in the image based on the image signal. A contrast value generation unit that generates a contrast value in a configured target region, a correction value generation unit that generates a correction value based on at least a part of the feature information, the contrast value, and the image signal; An adjustment value generation unit configured to generate the adjustment value based on the expansion coefficient and the correction value.

  Further, the program according to the present invention includes a feature information generating unit that generates feature information indicating a plurality of types of features related to image brightness based on an image signal, and a luminance extension that performs luminance extension according to an adjustment value. A luminance expansion unit configured to generate an expansion coefficient based on at least a part of the feature information, and a target composed of a plurality of pixels included in the image based on the image signal A contrast value generation unit that generates a contrast value in a region; at least a part of the feature information; the correction value based on the contrast value; and the image signal; the expansion coefficient; And an adjustment value generation unit that generates the adjustment value based on the correction value.

  An information storage medium according to the present invention is an information storage medium that stores a computer-readable program, and stores the program.

  According to the present invention, a display device or the like can perform unintentional luminance flattening when performing luminance expansion by performing luminance expansion using an adjustment value corresponding to a contrast value in a target region including a plurality of pixels. Can be prevented more appropriately.

  The contrast value generation unit may generate a first difference value that is a difference value between a maximum luminance value and a minimum luminance value in the target region as the contrast value.

  According to this, since the display device or the like can grasp the difference in the luminance value of the target region and can perform the luminance expansion according to the difference, the occurrence of unintended luminance flattening can be more appropriately performed. Can be prevented.

  In addition, the correction value generation unit calculates a second difference value that is a difference value between a white peak value included in the feature information and a luminance value of a target pixel based on the image signal, and the second difference The correction value may be generated based on a value, the contrast value, and correction value generation data in which the second difference value, the contrast value, and the correction value are associated with each other.

  According to this, since the display device or the like can grasp the difference between the luminance value of the target pixel and the white peak value and can perform luminance expansion according to the difference, unintentional luminance flattening can be performed. Occurrence can be prevented more appropriately.

  The correction value generation data may be set such that the smaller the contrast value and the second difference value, the smaller the correction value.

  According to this, since the display device or the like can perform luminance expansion using a small correction value when the contrast value or the like is small, it is possible to more appropriately prevent the occurrence of unintended luminance flattening.

  The feature information generation unit may generate at least information indicating a white peak value and information indicating APL as feature information indicating the plurality of types of features.

  According to this, the display device or the like can perform appropriate expansion according to the brightness of the image by using the white peak value and the APL.

  The coefficient generation unit generates the expansion coefficient based on the white peak value, the APL, and coefficient generation data in which the white peak value, the APL, and the expansion coefficient are associated with each other. Also good.

  According to this, the display device or the like can perform appropriate expansion according to the brightness of the image by determining the expansion coefficient from the white peak value and the APL.

  Further, a light control unit that performs light control based on the feature information or the expansion coefficient may be included.

  According to this, the display device or the like can display an image with appropriate brightness by performing luminance expansion and dimming.

It is a functional block diagram of the projector in a 1st Example. It is a flowchart which shows the projection procedure of the image in a 1st Example. It is a flowchart which shows the expansion | extension processing procedure in a 1st Example. It is a schematic diagram of the expansion coefficient generation data in the first embodiment. It is a schematic diagram when four points are defined in the expansion coefficient generation data in the first embodiment. It is a schematic diagram when three points are defined in the expansion coefficient generation data in the first embodiment. It is a schematic diagram of the correction value generation data in the first embodiment. It is a flowchart which shows the light control process sequence in a 1st Example.

  Embodiments in which the present invention is applied to a projector will be described below with reference to the drawings. In addition, the Example shown below does not limit the content of the invention described in the claim at all. In addition, all the configurations shown in the following embodiments are not necessarily essential as means for solving the invention described in the claims.

(First embodiment)
FIG. 1 is a functional block diagram of a projector 100 according to the first embodiment. The projector 100 generates an image signal input unit 110 that inputs an image signal (for example, a moving image signal such as an RGB signal) and feature information related to the brightness of an image represented by the image signal based on the image signal. The image forming apparatus includes a feature information generation unit 120, a luminance expansion unit 150 that performs luminance expansion, a projection unit 190 that includes a light adjustment unit 192, and a light adjustment processing unit 160 that controls the light adjustment unit 192. The dimming processing unit 160 includes a dimming coefficient generation unit 162 that generates a dimming coefficient, and a dimming control unit 164 that controls the dimming unit 192 according to the dimming coefficient.

  The luminance expansion unit 150 also generates an expansion coefficient generation unit 152 that generates an expansion coefficient based on at least a part of the feature information, and a contrast value in a target region that includes a plurality of pixels included in the image based on the image signal. A contrast value generation unit 153 to generate, a correction value generation unit 154 that generates a correction value based on at least part of the feature information, a contrast value, and an image signal, an expansion coefficient, and an adjustment value based on the correction value. An adjustment value generation unit 155 to be generated and an expansion processing unit 156 that performs an expansion process on the image signal in accordance with the adjustment value are configured.

  Note that the projector 100 may implement the functions of these units using the following hardware. For example, the projector 100 includes an image signal input unit 110, an image input terminal, a converter, etc., a feature information generation unit 120, an image processing circuit, etc., a luminance expansion unit 150, a dimming processing unit 160, a CPU, RAM, an image processing circuit, etc. The projection unit 190 is a lamp, a liquid crystal panel, a liquid crystal drive circuit, a lens, and the like. The light control unit 192 is a lamp power supply unit (having a function of adjusting the brightness of the lamp by power control) and a light shielding plate (a function of blocking the output light beam). May be mounted using a liquid crystal light valve (having a function of blocking output light).

  Further, the projector 100 may read the program stored in the information storage medium 200 and execute the process of the feature information generation unit 120 and the like. As such an information storage medium 200, for example, a CD-ROM, DVD-ROM, ROM, RAM, HDD, or the like can be applied.

  Next, an image projection procedure using these units will be described. FIG. 2 is a flowchart showing a procedure for projecting an image in the first embodiment. The feature information generation unit 120 generates feature information based on the image signal from the image signal input unit 110 (step S1).

  The feature information includes, for example, a luminance histogram (data indicating the frequency for each gradation level from the lowest gradation to the highest gradation in the entire image or a predetermined area in the image), white peak value WP (entire image or in the image The luminance value of the pixel having the highest luminance value among the pixels in the predetermined area), APL (Average Picture Level), and the like. Further, the processing unit may be one pixel or a plurality of pixels. For example, the feature information generation unit 120 may process a 16 × 16 pixel block as one processing unit and an average luminance value of 16 × 16 pixels as a luminance value of the pixel block.

  The luminance value may be, for example, the maximum value among the R signal value, the G signal value, and the B signal value, or a value obtained by multiplying each signal value by a coefficient (for example, 0.299R + 0.587G). + 0.144B, 0.2126R + 0.7152G + 0.722B, etc.).

  After generating the feature information, the projector 100 executes the expansion process and the light control process (step S2). First, the decompression process procedure will be described.

  FIG. 3 is a flowchart showing the decompression processing procedure in the first embodiment. The expansion coefficient generation unit 152 generates the white peak value WP represented by the feature information, the APL represented by the feature information, the expansion coefficient generation data in which the white peak value and APL and the expansion coefficient are associated (for example, 2 The expansion coefficient Kgt is generated using a dimension lookup table (step S11).

  FIG. 4 is a schematic diagram of expansion coefficient generation data in the first embodiment. FIG. 5 is a schematic diagram when four points are defined in the expansion coefficient generation data in the first embodiment. FIG. 6 is a schematic diagram when three points are defined in the expansion coefficient generation data in the first embodiment.

  In FIG. 4, the circled part is a part for which a value is defined. The values of n1 to n7 are arbitrary integers from 1 to 1022, for example, n1 = 511, n2 = 551, n3 = 596, n4 = 649, n5 = 715, n6 = 793, and n7 = 894. In FIG. 3, the value is not defined at the lower right because the average value (APL) does not exceed the maximum value (white peak value).

  For example, when APL is 540 and the white peak value is 660, it is a portion between four points defined. In this case, as shown in FIG. 5, the expansion coefficient generation unit 152 calculates the expansion coefficient Kgt as (kg1 * S1 + kg2 * S2 + kg3 * S3 + kg4 * S4) / (S1 + S2 + S3 + S4). Find by calculation. For example, when APL is 400 and white peak value is 500, it is a portion between three defined points. In this case, as shown in FIG. 6, the expansion coefficient generator 152 calculates the expansion coefficient Kgt by calculating (kg1 * S1 + kg2 * S2 + kg3 * S3) / (S1 + S2 + S3).

  In this way, the expansion coefficient generation unit 152 can obtain the expansion coefficient Kgt by performing the interpolation operation even if the value is not defined in the expansion coefficient generation data.

  The luminance expansion unit 150 determines whether or not the processing for all pixels has been completed (step S12), and executes the following processing if the processing for all pixels has not been completed. First, the contrast value generation unit 153 sets the difference value (first difference value) between the maximum luminance value and the minimum luminance value in the target region configured by the target pixel and surrounding pixels (for example, eight pixels adjacent to the target pixel). ) As a contrast value CV (step S13). The contrast value is, for example, a value indicating a difference in brightness in the target area.

  The correction value generation unit 154 calculates a difference value (second difference value) DV between the white peak value and the luminance value of the target pixel (step S14), and generates the contrast value CV, the difference value DV, and the correction value generation data. Based on this, a correction value Cc is generated (step S15). The correction value is, for example, a value for correcting the expansion coefficient according to the brightness state in the target area.

  FIG. 7 is a schematic diagram of correction value generation data in the first embodiment. In FIG. 7, the circled part is a part for which a value is defined. The correction value generation data is represented by, for example, a two-dimensional lookup table as shown in FIG. Similar to the expansion coefficient generation data described above, the correction value generation unit 154 can generate a correction value by interpolation calculation even for a portion where no value is defined in the correction value generation data.

  In FIG. 7, for example, the correction value generation data is configured such that the correction value of the portion where the difference value DV is m8 and the contrast value CV is m8 is 1, and the correction value approaches 0 toward the lower left. May be. Further, the correction value when the contrast value is 0 may be 1. This is because when the difference value DV (brightness difference) is small and the contrast value is small, whiteout is likely to occur. Therefore, the correction value is reduced so that it does not expand so much. In other cases, whiteout is difficult to occur. This is because it is considered preferable to increase the correction value to obtain a high-contrast image.

  The adjustment value generation unit 155 generates an adjustment value (gain) Kg based on the expansion coefficient Kgt and the correction value Cc (step S16). Specifically, for example, Kg = 1 + Cc * Kgt / 256.

  The expansion processing unit 156 expands the luminance of the target pixel based on the adjustment value Kg (step S17). For example, the decompression processing unit 156 may perform decompression processing by calculating R ′ = (1 + Kg / 256) R, G ′ = (1 + Kg / 256) G, and B ′ = (1 + Kg / 256) B. Here, R ′, G ′, and B ′ are RGB image signal values after decompression, and R, G, and B are RGB image signal values before decompression.

  The luminance expansion unit 150 executes the above luminance expansion processing for all pixels. Next, the light control processing procedure will be described. FIG. 8 is a flowchart showing the dimming processing procedure in the first embodiment.

  The dimming coefficient generation unit 162 generates the dimming coefficient Kl based on the white peak value, the APL, and the dimming coefficient generation data, similarly to the luminance coefficient generation procedure in the luminance expansion processing procedure described above (step S21).

  The dimming control unit 164 calculates an aperture ratio A = Kl / 255 (step S22). And the light control part 164 controls the light control part 192 by the aperture ratio A (step S23). For example, it is brightest when the aperture ratio A is 1 (aperture ratio 100%), and darkest when the aperture ratio A is 0.

  After the expansion / dimming process (step S2) as described above, the luminance expansion unit 150 outputs the image signal after the luminance expansion to the projection unit 190 to generate an image, and the projection unit 190 performs luminance expansion and adjustment. An image is projected in a lighted state (step S3). The projector 100 determines whether or not the process should be terminated by turning off the power (step S4). If the process is not to be terminated, the processes of steps S1 to S4 described above are repeatedly executed.

  As described above, according to the present embodiment, the projector 100 performs the purpose of performing the luminance expansion by performing the luminance expansion using the adjustment value corresponding to the contrast value in the target area composed of a plurality of pixels. It is possible to more appropriately prevent occurrence of brightness flattening. In particular, according to the present embodiment, the projector 100 can prevent overexposure over a wide range and can project a high-quality image.

  In addition, according to the present embodiment, the projector 100 can grasp the difference in the luminance value of the target region and can perform luminance expansion according to the difference. It can prevent more appropriately.

  Further, according to the present embodiment, the projector 100 can grasp the difference between the luminance value of the target pixel and the white peak value, and can perform luminance expansion according to the difference. The occurrence of flattening can be prevented more appropriately.

  Further, according to the present embodiment, the projector 100 can perform luminance expansion using a small correction value when the contrast value or the like is small, and thus more appropriately prevent the occurrence of unintended luminance flattening. Can do.

  Further, according to the present embodiment, the projector 100 can perform appropriate expansion according to the brightness of the image by using the white peak value and the APL, and determines the expansion coefficient from the white peak value and the APL. Thus, it is possible to perform appropriate expansion according to the brightness of the image.

  Further, according to the present embodiment, the projector 100 can display an image with appropriate brightness while increasing the contrast of the image by performing luminance expansion and dimming.

(Second embodiment)
In the first embodiment, the dimming coefficient generation unit 162 generates the dimming coefficient by the same method as the expansion coefficient, but generates the dimming coefficient based on the expansion coefficient generated by the expansion coefficient generation unit 152. May be. For example, the dimming coefficient generation unit 162 may calculate (1 + expansion coefficient Kgt / 255) ^−2.2 as the dimming coefficient.

  Accordingly, the projector 100 can perform dimming without using dimming coefficient generation data.

(Other examples)
In addition, application of this invention is not limited to the Example mentioned above, A various deformation | transformation is possible. For example, the above-described dimming is not essential, and the present invention is effective when only luminance expansion is performed. For example, when only luminance expansion is performed, the light control processing unit 160 and the light control unit 192 are unnecessary.

  The generation target of the feature information is not limited to the entire image, for example, excluding the pixels in the peripheral portion of the image, the pixels in the upper and lower portions of the image, the pixels in the left and right portions of the image, and the pixels in the lower portion of the image. It may be the central block of the image. For example, the feature information generation unit 120 generates the feature information indicating the feature of the image without being affected by the caption even if the image is combined with the caption by removing the lower pixel of the image. Can do.

  The number of pixels in the target region is not limited to 9 pixels, and may be 2 pixels or more and 8 pixels or less, or 10 pixels or more. For example, the target region may be configured with four pixels adjacent to the target pixel and above and below the target pixel, or may be configured with four pixels diagonally adjacent to the target pixel and the target pixel.

  Further, the present invention may be applied to display devices other than the projector 100, such as a television and a liquid crystal monitor. The projector 100 is not limited to a liquid crystal projector (transmission type, reflection type such as LCOS), and may be a projector using a DMD (Digital Micromirror Device), for example. DMD is a trademark of Texas Instruments Incorporated. Further, the functions of the projector 100 may be distributed and implemented in a plurality of devices (for example, a PC and a projector).

  100 projector, 110 image signal input unit, 120 feature information generation unit, 150 luminance expansion unit, 152 expansion coefficient generation unit, 153 contrast value generation unit, 154 correction value generation unit, 155 adjustment value generation unit, 156 expansion processing unit, 160 Light control processing unit, 162 Light control coefficient generation unit, 164 Light control unit, 190 Projection unit, 192 Light control unit, 200 Information storage medium

Claims (5)

A feature information generating unit that generates feature information indicating a plurality of types of features related to image brightness based on an image signal;
A luminance expansion unit for performing luminance expansion on the image signal based on the adjustment value;
Including
The luminance expansion unit is
An expansion coefficient generation unit that generates an expansion coefficient based on the white peak value and APL included in the feature information , and coefficient generation data in which an expansion coefficient corresponding to the white peak value and the APL is defined ;
A contrast value generation unit that generates, as a contrast value , a first difference value that is a difference value between a maximum luminance value and a minimum luminance value in a target region including a plurality of pixels included in the image, based on the image signal;
A second difference value that is a difference value between a white peak value included in the feature information and a luminance value of a target pixel based on the image signal is calculated, and the second difference value and the contrast value are calculated. A correction value generation unit that generates a correction value for correcting the expansion coefficient based on the difference value of 2 and correction value generation data in which a correction value corresponding to the contrast value is defined ;
An adjustment value generating unit that generates the adjustment value based on the expansion coefficient and the correction value;
including,
Display device. The display device according to claim 1 ,
The correction value generation data is set such that the correction value is smaller as the contrast value and the second difference value are smaller.
Display device. The display device according to claim 1, 2,
A dimming unit for dimming based on the feature information or the expansion coefficient;
Display device. Computer
A feature information generating unit that generates feature information indicating a plurality of types of features related to image brightness based on an image signal;
Based on the adjustment value, function as a luminance expansion unit that performs luminance expansion on the image signal ,
The luminance expansion unit is
An expansion coefficient generation unit that generates an expansion coefficient based on the white peak value and APL included in the feature information , and coefficient generation data in which an expansion coefficient corresponding to the white peak value and the APL is defined ;
A contrast value generation unit that generates, as a contrast value , a first difference value that is a difference value between a maximum luminance value and a minimum luminance value in a target region including a plurality of pixels included in the image, based on the image signal;
A second difference value that is a difference value between a white peak value included in the feature information and a luminance value of a target pixel based on the image signal is calculated, and the second difference value and the contrast value are calculated. A correction value generation unit that generates a correction value for correcting the expansion coefficient based on the difference value of 2 and correction value generation data in which a correction value corresponding to the contrast value is defined ;
An adjustment value generating unit that generates the adjustment value based on the expansion coefficient and the correction value;
including,
program. An information storage medium storing a computer-readable program,
An information storage medium storing the program according to claim 4 .

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