JP2009025445A - Dimming system, display device, program, information memory medium and light control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device and the like capable of appropriately dimming in an image even when a person passes in front of a light source. <P>SOLUTION: The display device 100 includes: an image characteristics information generating unit 120 for generating image characteristics information based on an image signal; a temporary dimming rate computing unit 131 for computing a temporary dimming rate based on the image characteristics information and dimming rate data; a dimming rate difference computing unit 132 for computing a dimming rate difference that represents a difference value between a dimming rate applied to the past image and the temporary dimming rate; a dimming correction determining unit 133 for determining a dimming correction amount based on the dimming rate difference; a dimming correction coefficient determining unit 134 for determining a dimming correction coefficient based on the image characteristics information; a dimming rate computing unit 135 for computing the dimming rate to be applied to the current image by adding a product of the dimming correction amount and the dimming correction coefficient to the dimming rate applied to the past image; and a dimming control unit 136 for controlling a dimming unit 180 based on the dimming rate to be applied to the current image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  As described in Japanese Patent Laid-Open No. 2006-64825, it has been proposed to adjust light according to the brightness of an image. Specifically, in the publication, a method of dimming in real time, a method of dimming by using a low-pass filter to cut a fine change, and when there is a change in brightness over a certain amount, that is, A technique for dimming only when the scene changes has been proposed.

  However, in the method of dimming only when the scene changes according to the brightness of the video, the brightness may change greatly even though the scene has not changed. For example, in a video, a person passes in front of a light source. In this case, the brightness changes greatly between the state where the light source is in the shadow of a person and the state where the light source is not in the shadow of a person. Despite the absence, it is determined that the scene has changed.

In addition, as a method for determining a scene change, Japanese Patent Application Laid-Open No. 7-288840 obtains an edge strength coefficient for each frame, and extracts a section where the edge strength coefficient changes greatly over a predetermined time and a section where the edge strength coefficient hardly changes. A method for detecting a change in a scene by performing processing is described.
JP 2006-64825 A JP-A-7-288840

  However, Japanese Patent Laid-Open No. 7-288840 is a technique for detecting scene changes due to cuts, editing effects, and camera operations, and thus is not a technique that can cope with cases where a person passes in front of a light source in an image.

  An object of the present invention is to provide a dimming system, a display device, and a dimming system capable of performing appropriate dimming even when there is a temporary luminance change in the same scene that a person passes in front of a light source in an image. To provide a program, an information storage medium, and a dimming method.

  In order to solve the above-described problem, a light control system according to the present invention includes an image feature information generation unit that generates image feature information indicating image features based on an image signal, the image feature information, the image feature information, and Based on the dimming rate data indicating the relationship of the temporary dimming rate, a temporary dimming rate calculating unit that calculates the temporary dimming rate, and a difference value between the applied dimming rate of the past image and the temporary dimming rate. A dimming rate difference value calculating unit that calculates a dimming rate difference value to be displayed, a dimming correction amount determining unit that determines a dimming correction amount based on the dimming rate difference value, and a dimming rate based on the image feature information. A dimming correction coefficient determination unit that determines a light correction coefficient, and calculates an applied dimming ratio of the current image obtained by adding the product of the dimming correction amount and the dimming correction coefficient to the applied dimming ratio of the past image A dimming rate calculating unit that controls the dimming unit based on the applied dimming rate of the current image, The dimming correction amount determination unit is a case where the dimming rate difference value is within a predetermined range including 0, or the dimming rate difference value is outside the predetermined range, and When the temporary dimming rate changes for each image, the dimming correction amount is determined to be a first value, the dimming value is outside the predetermined range, and the temporary dimming rate Is not changed for each image, the dimming correction amount is determined to be a second value larger than the first value.

  According to another aspect of the present invention, there is provided a display device including the dimming system and a display unit that displays an image in a dimmed state by the dimming system.

  Further, a program according to the present invention is a computer-readable program, and the computer uses an image feature information generating unit that generates image feature information indicating image characteristics based on an image signal, and the image feature information , A temporary dimming rate calculation unit for calculating a temporary dimming rate based on the image feature information and dimming rate data indicating a relationship between the temporary dimming rate, an applied dimming rate of a past image, and the temporary dimming A dimming rate difference value calculating unit that calculates a dimming rate difference value indicating a difference value from the rate, a dimming correction amount determining unit that determines a dimming correction amount based on the dimming rate difference value, and the image A dimming correction coefficient determining unit that determines a dimming correction coefficient based on the feature information, and a current image obtained by adding a product of the dimming correction amount and the dimming correction coefficient to an applied dimming rate of a past image. A dimming rate calculation unit for calculating an applied dimming rate, and the current image The dimming correction amount determining unit is configured to function as a dimming control unit that controls the dimming unit based on the dimming rate for use. When the light rate difference value is outside the predetermined range and the temporary light control rate changes for each image, the light control correction amount is determined as a first value, and the light control value Is outside the predetermined range and the provisional dimming rate does not change for each image, the dimming correction amount is determined to be a second value larger than the first value. Features.

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

  In the light control method according to the present invention, the image feature information generation unit generates an image feature value for each image processing unit based on the image signal, and the difference value calculation unit calculates the current image feature value and the past image. When the difference value with the feature value is calculated, and the light control unit satisfies the condition that the difference value is equal to or greater than a predetermined value and the difference value does not change periodically, the condition The amount of change in the amount of light is increased as compared with a case not corresponding to the above.

  According to the present invention, the light control system or the like can reduce the change in the amount of light even when the change in the image is large, if the change is periodic. As a result, the dimming system or the like does not react sensitively even if there is a temporary luminance change in the same scene that a person crosses in front of the light source, and performs appropriate dimming. be able to.

  In addition, the image feature information generation unit includes, as the image feature information, a maximum luminance value in one image processing unit, an APL in the one image processing unit, a difference value between the edge strength of the current image and the edge strength of the past image. And the provisional dimming rate calculation unit, the dimming rate data indicating the maximum luminance value, the APL, and the relationship between the maximum luminance value, the APL, and the temporary dimming rate; The provisional dimming rate may be calculated based on the above, and the dimming correction coefficient determination unit may determine the dimming correction coefficient based on the edge intensity difference value.

  According to this, the dimming system or the like can appropriately perform dimming by applying the maximum luminance value, APL, and edge strength as image features.

  The image feature information generation unit calculates the edge strength in the vertical direction of all pixels constituting one image and the edge strength in the horizontal direction of all pixels constituting one image, and obtains the current edge strength in the vertical direction. The difference value between the past edge strength in the vertical direction and the difference value between the current horizontal edge strength and the past horizontal edge strength are calculated, and the larger difference value among these difference values is calculated as the edge. You may produce | generate as an intensity | strength difference value.

  According to this, the dimming system or the like calculates the edge strength in the vertical direction and the horizontal direction separately, compares the magnitude, and uses the larger change as the edge strength difference value, thereby appropriately changing the image. I can grasp it.

  Further, the dimming rate calculating unit determines whether the edge intensity difference value exceeds a threshold value, and when the edge intensity difference value exceeds a threshold value, the provisional dimming rate is used as the applied dimming rate. When the light intensity is applied and the edge intensity difference value does not exceed a threshold value, a value obtained by adding the product of the correction amount and the correction coefficient to the application light adjustment ratio of the past image as the application light adjustment ratio May be applied.

  According to this, the dimming system or the like applies a temporary dimming rate unrelated to the applied dimming rate of the past image as the applied dimming rate when the current image and the past image are greatly different, Appropriate dimming can be performed by applying a value reflecting the applied dimming rate of the past image as the applied dimming rate when the previous image is similar to the past image.

  The image feature information generation unit may obtain the maximum luminance value and the APL using a central region that includes a central pixel of the image and does not include a peripheral pixel of the image as the one image processing unit.

  According to this, the dimming system or the like generates the image feature information for the central region of the image, and thereby the content of the image is not affected by the subtitles and black bands included in the peripheral region of the image. It is possible to appropriately grasp the characteristics corresponding to the.

  Further, the image feature information generation unit performs different weighting operations on a central region that includes a central pixel of the image and does not include a peripheral pixel of the image and a peripheral region other than the central region of the image, and performs the current calculation. The edge strength of the image may be obtained.

  According to this, the dimming system or the like, for example, reflects the edge intensity of the central area of the image more than the edge intensity of the peripheral area, so that the content of the image is not affected by subtitles or black bands. It is possible to appropriately grasp the characteristics corresponding to the.

  The dimming system includes: a temporary expansion rate determination unit that determines a temporary expansion rate based on the image feature information and expansion rate data indicating a relationship between the image feature information and the temporary expansion rate; An expansion rate difference value calculating unit that calculates an expansion rate difference value indicating a difference value between an applied expansion rate and the temporary expansion rate; an expansion correction amount determining unit that determines an expansion correction amount based on the expansion rate difference value; Based on the image feature information, an expansion correction coefficient determination unit that determines an expansion correction coefficient, and an applied expansion ratio of the current image obtained by adding a product of the expansion correction amount and the expansion correction coefficient to an application expansion ratio of a past image And a decompression unit that decompresses the image signal based on the currently applied decompression rate of the image.

  According to this, the dimming system or the like can appropriately perform not only dimming but also image expansion.

  Further, the dimming system includes: an expansion rate calculating unit that calculates an applied expansion rate of the current image based on the applied dimming rate of the current image; and the image signal based on the applied expansion rate of the current image. And a stretching section that stretches.

  According to this, the dimming system or the like can appropriately perform not only dimming but also image expansion. In particular, by performing image expansion using the applied dimming rate, the configuration of the image expansion processing unit can be simplified.

  Embodiments in which the present invention is applied to a display device 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 display device 100 according to the first embodiment. The display device 100 includes an image signal input unit 110 that inputs an image signal, an image feature information generation unit 120 that generates image feature information indicating image characteristics based on the image signal, a dimming unit 180, and image feature information. The dimming processing unit 130 for controlling the dimming unit 180, the luminance expansion processing unit 170 for expanding the image signal based on the image feature information, and the display unit 190 for displaying an image based on the expanded image signal. It is comprised including.

  The dimming processing unit 130 also determines a temporary dimming rate calculation unit 131 that calculates a temporary dimming rate, a dimming rate difference value calculation unit 132 that calculates a dimming rate difference value, and a dimming correction amount. The dimming correction amount determining unit 133, the dimming correction coefficient determining unit 134 for determining the dimming correction coefficient, the dimming rate calculating unit 135 for calculating the applied dimming rate of the current image, and the dimming unit 180 are controlled. And a dimming control unit 136.

  Note that, for example, the following hardware may be employed as hardware for implementing the functions of these units. For example, the image signal input unit 110 is an image input port, an A / D conversion circuit, the image feature information generation unit 120 is an image processing circuit, the dimming processing unit 130, and the luminance expansion processing unit 170 is a CPU, image processing A circuit, a RAM, etc., a light-blocking plate or the like as the dimmer 180, and a lamp, a liquid crystal panel, a projection lens, or the like as the display 190 may be employed. The display device 100 may be, for example, a liquid crystal projector, a projector using a DMD (Digital Micromirror Device), a television, a liquid crystal display, or the like. DMD is a trademark of Texas Instruments Incorporated.

  Further, the display device 100 may implement the function of the light control processing unit 130 by reading a program from the information storage medium 200. As such an information storage medium 200, for example, a CD-ROM, DVD-ROM, ROM, RAM, HDD or the like can be applied, and the program reading method may be a contact method or a non-contact method. Good.

  Next, a light control processing procedure using the light control processing unit 130 will be described. FIG. 2 is a flowchart showing a processing procedure from input of an image signal to calculation of a dimming rate difference value in the first embodiment.

  The image signal input unit 110 inputs an image signal (eg, RGB signal, YUV signal) from an image supply device such as a PC (Personal Computer) (step S1). The image feature information generation unit 120 determines the maximum luminance value WP and APL (Average Picture Level) as the image feature information based on the image signal from the image signal input unit 110 (step S2).

  More specifically, for example, the image feature information generation unit 120 uses one image processing unit (for example, one frame, one field, a central area in one image) as a pixel block (for example, 16 × 16 pixels, 4 × 4). And calculate the average luminance value of the pixel block, determine the maximum average luminance value among the average luminance values of all pixel blocks as the maximum luminance value, and average the average luminance value of all pixel blocks. Is determined as APL.

  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 the sum of 0.299 × R signal value, 0.587 × G signal value, and 0.144 × B signal value. Value or a Y value of a YUV signal.

  Also, the image feature information generation unit 120 calculates the vertical edge strength and the horizontal edge strength using the vertical filter and the horizontal filter for all pixels, and the total value of the horizontal edge strengths. Ex (0) and the total value Ey (0) of the edge strength in the vertical direction are calculated (step S3). For example, a general filter such as a Sobel filter or a Prewitt filter may be employed as the filter.

  Then, the image feature information generation unit 120 calculates the difference value dEx between the total value Ex (-1) of the horizontal edge strength of the previous frame and the total value Ex (0) of the horizontal edge strength of the current frame. (0) The difference value dEy (0) between the total value Ey (-1) of the vertical edge strength of the previous frame and the total value Ey (0) of the vertical edge strength of the current frame is calculated. (Step S4). Further, the image feature information generation unit 120 determines the larger one of the difference values dEx (0) and dEy (0) as the edge strength difference value dE of the image (step S5). Note that the image feature information generation unit 120 may store the edge strength for at least one frame in the internal memory by the first-in first-out method.

  The temporary dimming rate calculating unit 131 calculates a temporary dimming rate kg (0) based on the maximum luminance value WP, APL, and dimming rate data (step S6). FIG. 3 is a schematic diagram illustrating an example of dimming rate data in the first embodiment. Note that the values of the maximum luminance values WP and APL are arbitrary, but here, they are represented by 10 bits and are 1023 at the maximum.

  As shown in FIG. 3, the dimming rate data is APL on the horizontal axis and the maximum luminance value WP on the vertical axis, and is divided into 9 ranges from 0 to 1023, and the temporary dimming rate is at the intersection of each dividing line. Is defined. The dimming rate data is set to an appropriate value, for example, through an experiment or the like using the display device 100 that is actually applied.

  Since the APL never exceeds the maximum brightness value WP, the provisional dimming rate does not need to be defined at the intersection of the parting lines where the APL exceeds the maximum brightness value WP. Reduced. Further, when the intersection of the actual APL and the maximum luminance value WP is not at the intersection shown in FIG. 3, the temporary dimming rate calculation unit 131 performs the interpolation calculation using the defined temporary dimming rate, thereby performing the temporary adjustment. Calculate the light rate kg (0).

  The dimming rate difference value calculation unit 132 calculates a dimming rate difference value dwg that is a difference value between the applied dimming rate ktg (-1) and the temporary dimming rate kg (0) one frame before (step S7). ).

  The dimming rate difference value calculation unit 132 may store the applied dimming rate for at least one frame in the internal memory by the first-in first-out method. The applied dimming rate is a value that is actually applied as the dimming rate, and the temporary dimming rate is a value that is temporarily used as the dimming rate in order to perform calculation.

  Next, a processing procedure from determination of the dimming correction amount to dimming control will be described. FIG. 4 is a flowchart illustrating a processing procedure from determination of the dimming correction amount to dimming control in the first embodiment.

  The dimming correction amount determination unit 133 determines whether or not the dimming rate difference value dwg obtained by the dimming rate difference value calculation unit 132 is 0 (step S11). When the dimming rate difference value dwg is 0, that is, when the applied dimming rate ktg (-1) one frame before and the temporary dimming rate kg (0) match, the dimming correction amount determination unit 133 Then, the dimming correction amount dktg (0) is determined to be 0 (step S12). The dimming correction amount determination unit 133 may store provisional dimming rates for a plurality of frames in an internal memory by a first-in first-out method.

  On the other hand, when the dimming rate difference value dwg is other than 0, the dimming correction amount determining unit 133 calculates the difference between the temporary dimming rate kg (0) of the current frame and the temporary dimming rate kg (-2) of the previous frame. A match is determined (step S13). If they match, a mismatch between the temporary dimming rate kg (0) of the current frame and the temporary dimming rate kg (-1) of the previous frame is determined (step S14). When all of these determination results are true, that is, when it is considered that the edge intensity changes periodically, the dimming correction amount determination unit 133 determines the dimming correction amount dktg (0) to be 0. (Step S12).

  On the other hand, when one of the determination results of steps S13 and S14 is false, that is, when it is considered that the edge intensity is not periodic but generally changes, the dimming correction amount determination unit 133 adjusts the dimming correction amount determination unit 133. Based on the light rate difference value dwg and the dimming correction data, the dimming correction amount dktg (0) is determined (step S15).

  The dimming correction data is, for example, data indicating the relationship between the dimming rate difference value dwg and the dimming correction amount dktg (0), the temporary dimming rate kg (0), and the dimming correction amount dktg (0). (In this case, the dimming correction amount determination unit 133 obtains the dimming correction amount dktg (0) using the provisional dimming rate kg (0) and the dimming correction data). In addition, it is assumed that the light adjustment correction data is adjusted to an appropriate value in advance by an experiment or the like, for example. The dimming correction data may be stored in a memory inside the dimming correction amount determination unit 133, for example. Further, the dimming correction amount (second value) set in step S15 may be larger than the dimming correction amount (first value) set in step S12.

  The dimming rate calculation unit 135 determines whether the edge intensity difference value dE of the image obtained by the image feature information generation unit 120 exceeds the threshold Thg2 (step S16). Note that the threshold value Thg2 is a reference value for determining that the current frame and the past frame are irrelevant, and is set to an appropriate value by an experiment or the like, for example.

  When the edge intensity difference value dE of the image exceeds the threshold value Thg2, the dimming rate calculation unit 135 determines the applied dimming rate ktg (0) as the temporary dimming rate kg (0) (step S17).

  On the other hand, if the edge intensity difference value dE of the image does not exceed the threshold value Thg2, the dimming rate calculating unit 135 determines the dimming correction coefficient Sg based on the edge intensity difference value dE of the image (step S18). Specifically, for example, when the value obtained by dividing the edge intensity difference value dE of the image by an arbitrary value Thg1 is less than 1, the dimming rate calculating unit 135 sets the divided value as the dimming correction coefficient Sg, When the divided value is 1 or more, 1 is set as the dimming correction coefficient Sg. Here, 0 <Thg1 <Thg2.

  Further, when the edge intensity difference value dE of the image does not exceed the threshold value Thg2, the dimming rate calculation unit 135 applies the applied dimming rate ktg (0) = 1 to the applied dimming rate ktg (−1) + one frame before. The dimming correction amount dktg (0) * the dimming correction coefficient Sg is calculated to determine the applicable dimming rate ktg (0) (step S19). That is, when the change in the edge strength of the image is small, the applied dimming rate ktg (-1) one frame before is reflected in the current applied dimming rate ktg (0). The dimming rate calculation unit 135 may store the applied dimming rate for at least one frame in an internal memory by a first-in first-out method.

  The dimming control unit 136 controls the dimming unit 180 based on the applied dimming rate ktg (0) obtained by the dimming rate calculating unit 135 (step S20). Specifically, for example, the dimming control unit 136 transmits a motor drive signal for controlling the position of the light shielding plate arranged on the optical path, or transmits a control signal for controlling the drive power of the light source. To do. The display unit 190 displays an image based on the image signal expanded by the luminance expansion processing unit 170 while being dimmed by the dimming unit 180.

  As described above, according to the present embodiment, the display device 100 can reduce the change in the light amount when the change is periodic even when the change in the image is large. As a result, the display device 100 does not react sensitively even when there is a temporary luminance change in the same scene where a person crosses in front of the light source in the video, and performs appropriate light control. be able to.

  Further, according to the present embodiment, the display device 100 can perform dimming appropriately by applying the maximum luminance value, APL, and edge strength as image features. Further, according to the present embodiment, the display device 100 calculates the edge strength in the vertical direction and the horizontal direction individually, compares the magnitudes, and uses the larger change as the edge strength difference value, thereby changing the image. Can be grasped appropriately.

  Further, according to the present embodiment, the display device 100 applies, as the applied dimming rate, the temporary dimming rate that is not related to the applied dimming rate of the past image when the current image and the past image are greatly different. When the current image and the past image are similar, appropriate dimming can be performed by applying a value reflecting the applied dimming rate of the past image as the applied dimming rate.

(Second embodiment)
In the first embodiment, the present invention is applied to the dimming processing unit 130. However, the present invention may be applied to a luminance expansion processing unit. Next, an embodiment in which the present invention is applied to the luminance expansion processing unit will be described. FIG. 5 is a functional block diagram of the display device 101 in the second embodiment.

  The display device 101 includes a luminance expansion processing unit 171 instead of the luminance expansion processing unit 170 of the first embodiment. The luminance expansion processing unit 171 includes a temporary expansion rate calculation unit 173, an expansion rate difference value calculation unit 174, an expansion correction amount determination unit 175, an expansion correction coefficient determination unit 176, an expansion rate calculation unit 177, and an expansion unit 179. It is comprised including.

  The temporary expansion rate calculation unit 173 has the same configuration as the temporary dimming rate calculation unit 131, and is based on expansion rate data indicating the relationship between the maximum luminance value, APL, the maximum luminance value, APL, and the temporary expansion rate. Calculate the stretch rate. The expansion rate difference value calculation unit 174 has the same configuration as the dimming rate difference value calculation unit 132, and calculates an expansion rate difference value indicating a difference value between the applied image expansion rate and the temporary expansion rate of the past image. .

  The extension correction amount determination unit 175 has the same configuration as the dimming correction amount determination unit 133, and determines the extension correction amount based on the extension rate difference value. The expansion correction coefficient determination unit 176 has the same configuration as the dimming correction coefficient determination unit 134, and determines an expansion correction coefficient based on the edge intensity difference value.

  The expansion rate calculation unit 177 has the same configuration as the dimming rate calculation unit 135. In a predetermined case, the expansion rate calculation unit 177 adds the product of the expansion correction amount and the expansion correction coefficient to the application image expansion rate of the past image. Calculate the applied image expansion rate. The expansion unit 179 expands the image signal from the image signal input unit 110 based on the current image application expansion rate obtained by the expansion rate calculation unit 177.

  Further, the display device 101 may implement the functions of the dimming processing unit 130 and the luminance expansion processing unit 171 by reading a program stored in the information storage medium 201. The specific processing procedure is the same as that in the first embodiment, and will not be described.

  As described above, by applying the present invention to the luminance expansion processing unit 171, the display device 101 can change the luminance when the change is periodic even when the change in the image is large. Can be reduced. As a result, the display device 101 can perform appropriate image expansion without reacting sensitively even when there is a change in the video such that a person crosses in front of the light source.

(Third embodiment)
In the second embodiment, the luminance expansion processing unit 171 has the same configuration as the dimming processing unit 130, but the expansion rate may be calculated from the dimming rate. Next, an embodiment for calculating the expansion rate from the dimming rate will be described. FIG. 6 is a functional block diagram of the display device 102 in the third embodiment.

  The luminance expansion processing unit 172 includes an expansion rate calculating unit 178 that calculates the current applied expansion rate kta (0) based on the current applied dimming rate ktg (0) obtained by the dimming rate calculating unit 135, and An expansion unit 179 that expands the image signal based on the applied expansion rate is included.

For example, when the gamma value is 2.2, there is a relationship of ktg (0) = 1−kta (0) ^−2.2 . The expansion rate calculation unit 178 can calculate the applied expansion rate kta (0) from the applied dimming rate ktg (0) using this calculation formula. Of course, the application dimming rate ktg (0) can be obtained from the application expansion rate kta (0). In this case, the display device obtains the applied expansion rate kta (0) using the luminance expansion processing unit 171 of the second embodiment, and the dimming processing unit calculates the applied dimming rate from the applied expansion rate kta (0). What is necessary is just to have the light control rate calculating part which calculates ktg (0), and the light control part 136. FIG.

  Also in the third embodiment, the display device 102 may implement the functions of the dimming processing unit 130 and the luminance expansion processing unit 172 by reading a program stored in the information storage medium 202.

  As described above, according to the present embodiment, the display device 102 can calculate the applied expansion rate kta (0) from the applied dimming rate ktg (0), thereby simplifying the configuration of the display device 102. In addition, since the necessary calculation amount can be reduced, the decompression process can be executed more efficiently and appropriately.

(Fourth embodiment)
In the first to third embodiments, the image feature information generation unit 120 performs the calculation of the edge strength uniformly for all the pixels constituting the image. However, when the calculation of the edge strength is performed, A weighting operation may be performed according to the position. FIG. 7 is a diagram illustrating an example of the central region 310 and the peripheral region 320 in the fourth embodiment.

  For example, when the image feature information generation unit 120 targets the central region 310 that includes the central pixel of the image 300 and does not include the peripheral pixels of the image 300, the edge strength of the current image and the edge strength of the past image When a value obtained by multiplying the difference value by a first coefficient (for example, 1.0, 0.8, etc.) is obtained as the edge strength of the image and the peripheral region 320 other than the central region 310 of the image 300 is targeted, the current image A value (for example, 0.4, 0.2, etc.) obtained by multiplying the difference value between the edge strength of the previous image and the edge strength of the past image by a second coefficient smaller than the first coefficient may be obtained as the edge strength of the image.

  Further, for example, the image feature information generation unit 120 determines that the horizontal edge strength total value Ex (0) = the horizontal edge strength total value Ex1 (0) * 0.8 + the horizontal direction of the peripheral region 320 in the horizontal direction. The total edge strength value Ex2 (0) * 0.2 is calculated and the vertical edge strength total value Ey (0) = the central edge 310 vertical edge strength total value Ey1 (0) * 0.8 + peripheral region A total value Ey2 (0) * 0.2 of 320 edge strengths in the vertical direction may be calculated. Even with such a method, the edge strength of the image results in a value subjected to weighting calculation.

  As described above, according to the present embodiment, for example, the edge strength of the central region 310 of the image 300 is reflected more than the edge strength of the peripheral region 320, so that it is not affected by subtitles or black bands. Thus, it is possible to appropriately grasp the characteristics corresponding to the contents of the image 300.

(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 image feature information generation unit 120 may obtain the maximum luminance value and the APL using the central area 310 as one image processing unit. According to this, the display device 100 generates the image feature information for the central area 310, so that the display apparatus 100 can respond to the contents of the image 300 without being affected by the subtitles and black bands included in the peripheral area 320. It is possible to properly grasp the characteristics. In the above-described embodiments, the image processing unit is a frame, but may be a unit such as a field, a pixel block composed of a plurality of pixels, or the central region 310, for example.

  In the above-described embodiment, the image feature information generation unit 120 generates the maximum luminance value, the APL, and the edge strength difference value as the image feature information. However, other values may be generated as the image feature information. . For example, the image feature information generation unit 120 displays the minimum luminance value, the average luminance value, the representative luminance value (for example, the luminance value of a pixel at a predetermined position such as the center position), the variance value of the luminance value, the edge strength, and the like. It may be generated as image feature information.

  Further, the light control method is not limited to the above-described embodiment. For example, the image feature information generation unit generates an image feature value (image feature information) for each image processing unit based on the image signal, and the difference value calculation unit calculates the difference value between the image feature value and the past image feature value. The light control unit is a case where the difference value is equal to or greater than a predetermined value, and the case where the difference value does not change periodically is compared to the case where the difference value is not met Thus, the amount of change in the amount of light may be increased.

  That is, the display device determines the periodic change according to the difference between the characteristics of the past image and the characteristics of the current image, and executes the dimming process or the expansion process, so that an appropriate dimming process or A decompression process can be executed.

  In step S11, the dimming correction amount determination unit 133 determines whether or not the dimming rate difference value is 0. Instead of this determination, the dimming rate difference value includes a predetermined range including 0 (for example, It may be determined whether it is within 0 or more and 0.1 or less. The dimming correction amount determination unit 133 may determine whether or not the determinations in steps S12 and S13 are also within a predetermined range. Further, although the dimming correction amount determination unit 133 sets the dimming correction amount to 0 in step S12, the dimming correction amount may be set to a value other than zero.

  The applied dimming rate, expansion rate data, and the like one frame before may be stored in a memory of each unit such as the dimming rate difference value calculation unit 132 or may be stored in a shared accessible memory. Good. In the above-described embodiment, data of one frame before is used. For example, data of two frames before, an average value of data of a plurality of past frames, and the like are past data (for example, applied adjustment of past images). May be used as a light rate).

  Further, the functions of the display devices 100 to 102 may be distributed and implemented in a plurality of devices (for example, a PC and a projector). In addition, a device capable of mounting the light control system of the present invention is not limited to the display devices 100 to 102. For example, various image supply devices (for example, a PC, a DVD player, a game device, etc.) connected to the display device. It is possible to implement a dimming system.

It is a functional block diagram of the display apparatus in a 1st Example. It is a flowchart which shows the process sequence from the input of the image signal in 1st Example to the calculation of the light control rate difference value. It is a schematic diagram which shows an example of the light control rate data in a 1st Example. It is a flowchart which shows the process sequence from determination of the light control correction amount in 1st Example to light control. It is a functional block diagram of the display apparatus in a 2nd Example. It is a functional block diagram of the display apparatus in a 3rd Example. It is a figure which shows an example of the center area | region and peripheral area | region in a 4th Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Display apparatus, 110 Image signal input part, 120 Image feature information generation part, 130 Light control process part, 131 Temporary light control rate calculating part, 132 Light control rate difference value calculating part, 133 Light control correction amount determination part, 134 light control Light correction coefficient determination unit, 135 dimming rate calculation unit, 136 dimming control unit, 170 to 172 luminance expansion processing unit, 173 provisional expansion rate calculation unit, 174 expansion rate difference value calculation unit, 175 expansion correction amount determination unit, 176 Expansion correction coefficient determination unit, 177, 178 expansion rate calculation unit, 179 expansion unit, 180 dimming unit, 190 display unit, 200 to 202 information storage medium, 300 images, 310 central region, 320 peripheral region

Claims (12)

An image feature information generating unit for generating image feature information indicating the feature of the image based on the image signal;
Based on the image feature information and the dimming rate data indicating the relationship between the image feature information and the temporary dimming rate, a temporary dimming rate calculating unit that calculates a temporary dimming rate;
A dimming rate difference value calculating unit that calculates a dimming rate difference value indicating a difference value between the applied dimming rate of the past image and the temporary dimming rate;
A dimming correction amount determining unit that determines a dimming correction amount based on the dimming rate difference value;
A dimming correction coefficient determining unit that determines a dimming correction coefficient based on the image feature information;
A dimming rate calculator for calculating the applied dimming rate of the current image obtained by adding the product of the dimming correction amount and the dimming correction coefficient to the applied dimming rate of the past image;
A dimming control unit for controlling the dimming unit based on the applied dimming rate of the current image;
Including
The dimming correction amount determination unit is a case where the dimming rate difference value is within a predetermined range including 0, or the dimming rate difference value is outside the predetermined range, and the temporary dimming When the rate changes for each image, the dimming correction amount is determined as a first value, the dimming value is outside the predetermined range, and the temporary dimming rate is set for each image. If not, the dimming correction amount is determined to be a second value larger than the first value. The light control system according to claim 1,
The image feature information generation unit indicates, as the image feature information, a maximum luminance value in one image processing unit, an APL in the one image processing unit, and a difference value between the edge strength of the current image and the edge strength of the past image. Generate edge strength difference value,
The temporary dimming rate calculation unit calculates the temporary dimming rate based on the maximum luminance value, the APL, and the dimming rate data indicating the relationship between the maximum luminance value, the APL, and the temporary dimming rate. And
The dimming correction coefficient determination unit determines the dimming correction coefficient based on the edge intensity difference value. The light control system according to claim 2,
The image feature information generation unit calculates the vertical edge strength of all pixels constituting one image and the horizontal edge strength of all pixels constituting one image, and calculates the current vertical edge strength and the past The difference value between the edge strength in the vertical direction and the difference value between the current edge strength in the horizontal direction and the edge strength in the past horizontal direction are calculated, and the larger difference value among these difference values is calculated as the edge strength difference. Dimming system characterized by generating as a value. In the light control system in any one of Claim 2, 3,
The dimming rate calculation unit determines whether the edge intensity difference value exceeds a threshold value, and when the edge intensity difference value exceeds a threshold value, the provisional dimming rate as the applied dimming rate When the edge intensity difference value does not exceed a threshold value, a value obtained by adding the product of the correction amount and the correction coefficient to the applied dimming rate of the past image is applied as the applied dimming rate. A dimming system characterized by In the light control system in any one of Claims 2-4,
The image feature information generation unit obtains the maximum luminance value and the APL using a central region that includes a central pixel of an image and does not include peripheral pixels of the image as the one image processing unit. system. In the light control system in any one of Claims 2-5,
The image feature information generation unit performs a different weighting operation on a central area that includes a central pixel of the image and does not include a peripheral pixel of the image, and a peripheral area other than the central area of the image, thereby performing the current image Light control system characterized by obtaining edge strength of In the light control system in any one of Claims 1-6,
A temporary expansion rate determination unit that determines a temporary expansion rate based on the image feature information and expansion rate data indicating a relationship between the image feature information and the temporary expansion rate;
An expansion rate difference value calculation unit for calculating an expansion rate difference value indicating a difference value between an applied expansion rate of a past image and the temporary expansion rate;
An extension correction amount determination unit that determines an extension correction amount based on the extension rate difference value;
An expansion correction coefficient determination unit for determining an expansion correction coefficient based on the image feature information;
An expansion rate calculation unit that calculates an applied expansion rate of the current image obtained by adding a product of the expansion correction amount and the expansion correction coefficient to the application expansion rate of the past image;
A decompression unit for decompressing the image signal based on an applied decompression rate of the current image;
A dimming system comprising: In the light control system in any one of Claims 1-6,
Based on the applied dimming rate of the current image, an expansion rate calculation unit that calculates the applied expansion rate of the current image;
A decompression unit for decompressing the image signal based on an applied decompression rate of the current image;
A dimming system comprising: A dimming system according to any one of claims 1 to 8,
A display unit that displays an image in a dimmed state by the dimming system;
Display device. A computer-readable program,
Computer
An image feature information generating unit for generating image feature information indicating the feature of the image based on the image signal;
Based on the image feature information and the dimming rate data indicating the relationship between the image feature information and the temporary dimming rate, a temporary dimming rate calculating unit that calculates a temporary dimming rate;
A dimming rate difference value calculating unit that calculates a dimming rate difference value indicating a difference value between the applied dimming rate of the past image and the temporary dimming rate;
A dimming correction amount determining unit that determines a dimming correction amount based on the dimming rate difference value;
A dimming correction coefficient determining unit that determines a dimming correction coefficient based on the image feature information;
A dimming rate calculator for calculating the applied dimming rate of the current image obtained by adding the product of the dimming correction amount and the dimming correction coefficient to the applied dimming rate of the past image;
Based on the applied dimming rate of the current image, function as a dimming control unit that controls the dimming unit,
The dimming correction amount determination unit is a case where the dimming rate difference value is within a predetermined range including 0, or the dimming rate difference value is outside the predetermined range, and the temporary dimming When the rate changes for each image, the dimming correction amount is determined as a first value, the dimming value is outside the predetermined range, and the temporary dimming rate is set for each image. If not, the program adjusts the dimming correction amount to a second value larger than the first value. An information storage medium storing a computer-readable program,
An information storage medium storing the program according to claim 10. The image feature information generation unit generates an image feature value for each image processing unit based on the image signal,
The difference value calculation unit calculates a difference value between the current image feature value and the past image feature value,
When the dimming unit meets the condition that the difference value is greater than or equal to a predetermined value and the difference value does not change periodically, the change in the amount of light compared to when the condition does not meet the condition A dimming method characterized by increasing the amount.

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