JP2008046346A - Electric power consumption reduction apparatus, display device, image processor, electric power consumption reduction method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the electric power consumed in a display device cannot be surely reduced in the case of the conventional technique of controlling peak brightness dependently upon an input video signal. <P>SOLUTION: The electric power consumption reduction apparatus comprises a frame memory which accumulates an input video signal, an area division section which divides the input video signal accumulated in the frame memory to each coding block unit, a standard deviation value calculation section which calculates the standard deviation value of the input video signal corresponding to each coding block, a block noise region determination section which judges the corresponding coding block as a block noise region, in a case the standard deviation value is less than the threshold value, and a video signal output section which outputs the input video signal at the time of the input intact relating to the input video signal of the coding block judged to be the non-block noise region, and outputs the input video signal of the coding block judged to be block noise region by substituting the signal with a single gray scale signal of a smaller gray scale value than that of the input video signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention described in this specification relates to a technique for reducing power consumed in a display device that decodes and displays a video signal that is block-coded and transmitted or recorded.
The invention proposed by the inventors has aspects as a power consumption reduction device, a display device, an image processing device, a power consumption reduction method, and a computer program.

  Various display devices have been developed today. For example, liquid crystal display devices, plasma display devices, organic EL display devices, field emission display devices, projector devices (including projection type and rear type) and other display devices have been developed. In any display device, further reduction of power consumption is being studied, and various techniques have been proposed.

JP 2003-134418 A JP-A-2002-351389 discloses a technique for increasing the peak luminance on a display screen with a low average luminance and decreasing the peak luminance on a display screen with a high average luminance.

  However, the method of controlling the peak luminance depending on the input video signal cannot always reliably reduce the power consumed by the display device.

  Therefore, the inventors have (A) a frame memory for storing the input video signal, (B) an area dividing unit for dividing the input video signal stored in the frame memory into coding blocks, and (C) each encoding. A standard deviation calculating unit that calculates a standard deviation value of an input video signal corresponding to a block; and (D) a block noise region determining unit that determines a corresponding encoded block as a block noise region when the standard deviation value is less than a threshold value; (E) An input video signal of an encoded block determined to be a non-block noise region is output as it is input, while an input video signal of an encoded block determined to be a block noise region is input to the input video signal Proposed is a power consumption reduction device equipped with a video signal output unit that outputs a single gradation signal having a gradation value smaller than that of a signal.

This power consumption reduction apparatus detects a block noise region and replaces the display of the corresponding encoded block portion with a monochrome solid screen. Of course, the image quality of the corresponding area is lowered by the replacement process.
However, since the gradation value of the single gradation signal is smaller than the gradation value of the input video signal to be replaced, it is possible to reliably reduce the power consumed when displaying an image.

  According to the technical technique proposed by the inventors, the display image can be simplified by actively using block noise that appears at the time of encoding or decoding (including the display of all black in the corresponding area). Thus, it is possible to reliably reduce the power consumed when displaying the image.

Hereinafter, a technique for reducing power consumption according to the invention will be described.
In addition, the well-known or well-known technique of the said technical field is applied to the part which is not illustrated or described in particular in this specification.
Moreover, the form example demonstrated below is one form example of invention, Comprising: It is not limited to these.

(A) Embodiment (A-1) Functional Configuration of Power Consumption Reduction Device FIG. 1 shows a functional configuration example of the power consumption reduction device 1. The power consumption reduction apparatus 1 includes a frame memory 3, an area division unit 5, a noise region determination unit 7, and a video signal output unit 9.

  The frame memory 3 is a storage area or storage device that accumulates an input video signal for one frame for block noise determination processing. In this embodiment, a semiconductor memory is used as the physical storage medium.

The input video signal in this embodiment is assumed to be a signal obtained by decoding broadcast waves and streaming signals received in real time. The input video signal here is a digital signal that is compression-coded in a predetermined format. For example, MPEG (Moving Picture Experts Group) format or JPEG (Joint Photographic Experts)
Group) format.

  The area dividing unit 5 is a processing device that reads an input video signal from the frame memory 3 and divides it into encoded block units. The division size here matches the block size at the time of encoding. That is, the division size depends on the encoding format of the input video signal.

  In a compression encoding method that is widely used at present, encoding is performed in block units of 8 × 8 pixels or 16 × 16 pixels. FIG. 2 shows an example of a coding block composed of 8 pixels in each of the horizontal direction and the vertical direction.

  The noise region determination unit 7 is a processing device that determines the appearance of an encoded block recognized as block noise. In the case of this embodiment, the noise region determination unit 7 includes an average value calculation unit 71, a standard deviation calculation unit 73, and a block noise region determination unit 75. Block noise is a phenomenon in which a part of an image looks like a mosaic.

  In the high-efficiency coding method, generally, a technique for increasing compression efficiency by omitting high frequency components is used. A typical example is discrete cosine transform (DCT). Of course, if the compression rate is appropriate for the amount of information, block noise is not perceived. However, block noise may appear due to the amount of information and the limitation of the transmission band.

  The average value calculation unit 71 is a processing device that calculates the average gradation value of each coding block. In the case of this embodiment, the average value calculation unit 71 calculates an average value of 64 pixel values (gradation values) constituting the encoded block. The calculated average gradation value is output to the standard deviation calculation unit 73 and the block noise region determination unit 75.

The standard deviation calculation unit 73 is a processing device that calculates the standard deviation value of each coding block. Since the calculation of the standard deviation value itself is known, the details are omitted, but an operation such as the following equation is executed.
Standard deviation = √ {(Σ (pixel gradation n- average gradation value) ^2/64}

  Note that the pixel gradation n means the gradation value of one of the 64 pixels constituting the coding block. The operator Σ means that the square value of the difference value between the pixel gradation value and the average gradation value is added by the number of pixels (64). Of course, the denominator “64” means the number of pixels constituting the coding block.

  The block noise region determination unit 75 is a processing device that determines whether a corresponding encoded block is a block noise region or a non-block noise region based on the calculated average gradation value and standard deviation value. .

  In the case of this example, the block noise region has a calculated average gradation value lower than the determination threshold value (for average value), and the calculated standard deviation value is lower than the determination threshold value (for standard deviation). Define it as a small case. That is, the block noise region is determined when the coding block is entirely dark and the entire region is a uniform image.

Therefore, in the case of this embodiment, if the standard gradation value is large even if the average gradation value is small, or if the average gradation value is large even if the standard deviation value is small, it is determined as a non-blocking noise region.
The two determination threshold values used for this determination are given to the block noise region determination unit 75 from the outside. However, it is also possible to incorporate a determination threshold value.

  The video signal output unit 9 is a processing device that performs switching control of a video signal to be output based on a determination result in units of coding blocks. In the case of this embodiment, the video signal output unit 9 includes a power consumption control unit 91 and a frame memory 93.

  The power consumption control unit 91 instructs the output of the input video signal for an encoded block determined to be a non-block noise region, and the encoded block determined to be a block noise region is higher than the input video signal. This is a processing device that replaces a single gradation signal with a small tone value.

  In the case of this embodiment, the encoded block portion determined to be the block noise area in the input video signal stored in the frame memory 93 is replaced with black level (gradation value 0) data. As a result, the block noise area is converted to a black solid screen.

  The frame memory 93 is a storage area or storage device that accumulates an input video signal for one to several frames while the block noise is being determined. In this embodiment, a semiconductor memory is used as the physical storage medium.

  Note that the video signal read from the frame memory 93 (including black level data replaced in units of encoded blocks when block noise is included) is output to the display device 111. In the case of this embodiment, an organic EL display device that is a self-luminous display device is applied to the display device 111.

(A-2) Power Consumption Reduction Operation The processing operation of the power consumption reduction apparatus 1 will be described below using a specific display screen.
Here, it is assumed that an input video signal corresponding to the image shown in FIG. 3 is input to the power consumption reduction apparatus 1.

In FIG. 3, the block noise is emphasized from the viewpoint of drawing, but the actual luminance difference is very small.
In the case of FIG. 3, each encoded block is represented by a square area. FIG. 3 is a display example when the entire screen is composed of 18 encoded blocks in the horizontal direction and 13 encoded blocks in the vertical direction.

  In the case of FIG. 3, block noise appears on the entire screen. Therefore, the block noise region determination unit 75 performs an operation of determining these block noise regions and replacing them with black level data. However, only in the center of the screen where the character string is displayed, the standard deviation value is equal to or greater than the determination threshold value, and is determined as a non-blocking noise region.

  FIG. 4 is an example of a display screen output from the power consumption reduction apparatus 1. As shown in FIG. 4, all areas except for the center of the screen where the character string exists are converted to a black screen. That is, turn-off control is performed.

  As can be seen by comparing FIG. 3 and FIG. 4, the image information in the block noise region is completely lost by the power consumption reduction process. However, there is no problem because this image information is perceived as block noise even if it is displayed as input.

  Further, no current flows through the organic EL element due to the turn-off control of the block noise region. That is, it is possible to reduce the power consumed by light emission in the same area portion only to the non-block noise area portion. The greater the number of block noise regions that are controlled to be turned off, the greater the power consumption reduction effect.

  Also, the black level (gradation value 0) is uniformly written in the encoded block (64 pixels) determined to be a non-block noise area. For this reason, the power consumed when writing the gradation value for the corresponding pixel can also be reduced.

(B) Other Embodiments (B-1) Other Configuration Examples of the Power Consumption Reduction Device In the above-described embodiments, the average gradation value and the standard deviation value are used as determination criteria, and the coding block to be determined is The case where it is determined whether or not the block noise region has been described. However, other implementation methods are also conceivable.

(A) Modification 1
For example, it may be determined whether or not the coding block to be determined is a block noise region based on only the standard deviation value.
FIG. 5 shows a functional configuration example of the power consumption reduction apparatus 121. In FIG. 5, the same reference numerals are given to the portions corresponding to FIG. 1.

The power consumption reduction device 121 includes a frame memory 3, an area division unit 5, a noise region determination unit 123, and a video signal output unit 9.
The processing device itself constituting the noise region determination unit 123 is the same as the nozzle region determination unit 7 shown in FIG. However, in the case of FIG. 5, the average gradation value calculated by the average value calculation unit 71 is supplied only to the standard deviation value calculation unit 73.

  Accordingly, the block noise region determination unit 125 determines whether the corresponding encoded block is a block noise region or a non-block noise region based only on the calculated average gradation value. In this case, information on the average gradation value is ignored. For this reason, all coding blocks having a small standard deviation value are determined to be block noise regions.

  Therefore, when only the standard gradation value is used as the determination criterion, it is converted into a black screen including a bright screen portion. As a result, the power consumption reduction effect can be further enhanced.

(B) Modification 2
For example, each coding block determined to be a block nozzle area may be set to a value that is smaller than the average gradation value calculated for the coding block by a standard deviation value or less.

FIG. 6 shows a functional configuration example of the power consumption reduction device 131. In FIG. 6, parts corresponding to those in FIG.
The power consumption reduction device 131 includes a frame memory 3, an area division unit 5, a noise region determination unit 133, and a video signal output unit 141.

  The processing device itself constituting the noise region determination unit 133 is the same as the nozzle region determination unit 7 shown in FIG. However, in the case of FIG. 6, the block noise region determination unit 135 uses the value obtained by subtracting the standard deviation value from the average gradation value of the encoded block determined to be the block noise region as the replacement value, and the video signal output unit 141 (power consumption) To the controller 143).

  The power consumption control unit 143 controls the replacement of the encoded block corresponding to the block noise region with a non-zero (zero) single gradation value calculated based on the input video signal constituting each encoded block.

  As a result, the image is converted into a low-brightness image in which the density of the same region is reduced as compared to the case where the input video signal is displayed as it is on the display device screen. By executing this reduction operation, the luminance difference between the encoded blocks is reduced, and the block noise is hardly perceived accordingly. Also, the power consumption can be reduced compared to the case where the input video signal is displayed as it is.

(C) Modification 3
For example, it may be set to a value that is smaller than the average gradation value of all the coding blocks determined as the block nozzle region by a standard deviation value or less. That is, all the encoded blocks determined as the block noise region may be set to a single gradation value of a non-black level. This is the difference from the second modification.

FIG. 7 shows a functional configuration example of the power consumption reduction device 151. In FIG. 7, parts corresponding to those in FIG.
The power consumption reduction device 151 includes a frame memory 3, an area division unit 5, a noise region determination unit 7, an average value calculation unit 153, a standard deviation calculation unit 155, and a video signal output unit 161.

There are three new configurations in this modification: an average value calculation unit 153, a standard deviation calculation unit 155, and a video signal output unit 161.
The average value calculation unit 153 is a processing device that calculates the average gradation value of all the encoded blocks determined as the block noise region.

The standard deviation calculation unit 155 is a processing device that calculates standard gradation values of all coding blocks determined to be block noise regions.
The power consumption control unit 163 is a processing device that performs calculation (non-zero) of a gradation value to be replaced in an area determined to be a block noise area and replacement processing of an input video signal based on the calculated value.

  In the case of this modification, as shown in FIG. 8, all encoded blocks determined to be block noise areas are converted to the same gradation value in the entire screen. As a result, at the same time that the block noise is eliminated, the power consumption can be reduced as compared with the case where the input video signal is displayed as it is.

(B-2) Mounting Example Here, a mounting example of the above-described power consumption reduction apparatus in an electronic device will be described.

(A) Mounting on a self-luminous display device The power consumption reduction device described above can also be mounted on a display device 171 as shown in FIG.
A display device 171 illustrated in FIG. 9 includes a display device 173 and a power consumption reduction device 175.

The power consumption reduction device 175 can be realized with a small circuit. Therefore, the power consumption reduction device 175 can be stored in a part of an IC (integrated circuit) or the like mounted on the display device 173.
For example, in the case of the display device 173 having the device structure shown in FIG. 10, the power consumption reduction device 175 can be mounted on a part of the timing generator 181.

In this way, if it is mounted on a part of an existing processing circuit, it is not necessary to change the layout or the mounting space. Therefore, the manufacturing cost is also effective.
10 includes a timing generator 181, a data driver 183, a scan driver 185, and a display panel 187.

  The timing generator 181 is a processing device that generates various timing signals necessary for screen display based on a timing signal included in the video signal. For example, a write pulse is generated.

  The data driver 183 is a circuit device that drives data lines of the display panel 187. The data driver 183 performs an operation of converting a gradation value specifying the light emission luminance of each pixel into an analog voltage value and supplying the analog voltage value to the data line. The gradation value here is the gradation value after being processed by the power consumption reduction device 175.

The scan driver 185 is a circuit device that selects a horizontal line for writing gradation values in a line-sequential manner. This selection signal is output to the display panel 187 as the write pulse described above.
The display panel 187 is a well-known display device in which self-luminous elements are arranged in a matrix on the light emitting surface.

(B) Image Processing Device The power consumption reduction device described above can also be mounted on an image processing device 201 as an external device that supplies a video signal to the display device 191 as shown in FIG.

  An image processing apparatus 201 illustrated in FIG. 11 includes an image processing unit 203 and a power consumption reduction apparatus 205. Note that the processing content of the image processing unit 203 depends on the application executed by the image processing apparatus 201.

  The image processing apparatus 201 may be connected not only to the display apparatus 191 directly but also to the transmission apparatus 211 as shown in FIG. 12 or to the recording apparatus 221 as shown in FIG. .

  Here, the transmission device 211 realizes a function of transmitting a video signal to the transmission path in a signal form corresponding to the transmission standard. In addition, the recording device 221 realizes a function of storing the number in a recording medium in a signal format corresponding to the recording standard.

  That is, when a block noise area is detected immediately after the video signal is encoded, the video reproduced by the receiving apparatus or the reproducing apparatus is reduced in advance by reducing the gradation value of the encoded block corresponding to the area. A reduction in power consumed when the signal is displayed on the display device can be realized.

(C) Electronic device The power consumption reduction device described above can be mounted on various electronic devices including a self-luminous display device. Note that the electronic device here may be portable or stationary. In addition, the self-luminous display device is not necessarily installed in an electronic device.

(C1) Power Consumption Reduction Device The power consumption reduction device can be mounted on a broadcast wave reception device.
FIG. 14 shows a functional configuration example of the broadcast wave receiving apparatus. The broadcast wave receiving apparatus 231 includes a display panel 233, a system control unit 235, an operation unit 237, a storage medium 239, a power source 241 and a tuner 243 as main constituent devices.

  The system control unit 235 is constituted by a microprocessor, for example. The system control unit 235 controls the operation of the entire system. The operation unit 237 includes a graphic user interface in addition to a mechanical operator.

  The storage medium 239 is used as a storage area for firmware and application programs in addition to data corresponding to images and videos displayed on the display panel 233. The power source 241 uses a battery power source when the broadcast wave receiver 231 is portable. Of course, when the broadcast wave receiver 231 is a stationary type, a commercial power source is used.

The tuner 243 is a device that selectively receives a broadcast wave of a specific channel selected by the user from incoming broadcast waves.
This configuration of the broadcast wave receiving apparatus can be used when applied to, for example, a television program receiver or a radio program receiver.

(C2) Communication Device FIG. 15 is a functional configuration example when applied to a communication device. The communication device 251 includes a display panel 253, a system control unit 255, an operation unit 257, a storage medium 259, a power source 261, and a communication unit 263 as main constituent devices.

  Note that the system control unit 255 is configured by, for example, a microprocessor. The system control unit 255 controls the operation of the entire system. The operation unit 257 includes a graphic user interface in addition to a mechanical operator.

  The storage medium 259 is used as a storage area for firmware and application programs in addition to data files corresponding to images and videos displayed on the display panel 253. The power source 261 uses a battery power source when the communication device 251 is portable. Of course, when the communication device 251 is a stationary type, a commercial power source is used.

  The communication unit 263 is a wireless device that transmits and receives data to and from other devices. This configuration of the communication device can be used when applied to, for example, a stationary phone or a mobile phone.

(C3) Imaging Device FIG. 16 is a functional configuration example when applied to an imaging device. The imaging device 271 includes a display panel 273, a system control unit 275, an operation unit 277, a storage medium 279, a power supply 281 and an imaging unit 283 as main constituent devices.

  Note that the system control unit 275 is configured by, for example, a microprocessor. The system control unit 275 controls the operation of the entire system. The operation unit 277 includes a graphic user interface in addition to a mechanical operator.

  The storage medium 279 is used as a storage area for firmware and application programs in addition to data files corresponding to images and videos displayed on the display panel 273. The power source 281 uses a battery power source when the imaging device 271 is portable. Of course, when the imaging device 271 is a stationary type, a commercial power source is used.

  The imaging unit 283 is configured by, for example, a CMOS sensor and a signal processing unit that processes an output signal thereof. This configuration of the imaging apparatus can be used when applied to, for example, a digital camera, a video camera, or the like.

(C4) Information Processing Device FIG. 17 is a functional configuration example when applied to a portable information processing device. The information processing apparatus 291 includes a display panel 293, a system control unit 295, an operation unit 297, a storage medium 299, and a power supply 301 as main constituent devices.

  The system control unit 295 is constituted by a microprocessor, for example. The system control unit 295 controls the operation of the entire system. The operation unit 297 includes a graphic user interface in addition to a mechanical operator.

  The storage medium 299 is used as a storage area for firmware and application programs in addition to data files corresponding to images and videos displayed on the display panel 293. The power supply 301 uses a battery power supply when the information processing apparatus 291 is portable. Of course, when the information processing apparatus 291 is a stationary type, a commercial power source is used.

  This configuration of the information processing apparatus can be used when applied to, for example, a game machine, an electronic book, an electronic dictionary, a computer, and the like.

(B-3) Display Device In the above-described embodiment, the display device has been described as an organic EL display element that is one of self-luminous display devices.

  The display device here can be applied not only to inorganic EL display devices, FED display devices, and PDP display devices, which are other self-luminous display devices, but also to liquid crystal display devices, projector devices, which are non-self-luminous display devices.

  Note that in the case of a non-self light emitting display device, it is not possible to expect a reduction in power consumption due to a decrease in the light emission amount of the light emitting element, but at least the power consumption when writing pixel data to each pixel in the block noise region can be reduced. it can.

(B-4) Computer Program The power consumption reduction apparatus described in the above-described embodiments can realize not only all processing functions by hardware or software, but also by hardware and software function sharing.

(B-5) Others Various modifications can be considered for the above-described embodiments within the scope of the gist of the invention. Various modifications and applications created or combined based on the description of the present specification are also conceivable.

It is a figure which shows the function structural example of a power consumption reduction apparatus. It is a figure which shows the example of an encoding block. It is a figure which shows the example of a display screen before the reduction process of power consumption. It is a figure which shows the example of a display screen after the reduction process of power consumption. It is a figure which shows the other function structural example of a power consumption reduction apparatus. It is a figure which shows the other function structural example of a power consumption reduction apparatus. It is a figure which shows the other function structural example of a power consumption reduction apparatus. It is a figure which shows the example of a display screen after the reduction process of power consumption. It is a figure explaining the example of mounting of the power consumption reduction apparatus. It is a figure explaining the example of a device structure of a display device. It is a figure explaining the example of mounting of the power consumption reduction apparatus. It is a figure explaining the example of mounting of the power consumption reduction apparatus. It is a figure explaining the example of mounting of the power consumption reduction apparatus. It is a figure explaining the example of mounting to the electronic device of a power consumption reduction apparatus. It is a figure explaining the example of mounting to the electronic device of a power consumption reduction apparatus. It is a figure explaining the example of mounting to the electronic device of a power consumption reduction apparatus. It is a figure explaining the example of mounting to the electronic device of a power consumption reduction apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power consumption reduction apparatus 3 Frame memory 5 Area division part 7 Noise area determination part 71 Average value calculation part 73 Standard value calculation part 75 Block noise area determination part 9 Video signal output part 91 Power consumption control part 93 Frame memory 111 Display apparatus

Claims (12)

A frame memory for storing input video signals;
An area dividing unit for dividing the input video signal accumulated in the frame memory into encoded block units;
A standard deviation calculating unit for calculating a standard deviation value of an input video signal corresponding to each coding block;
When the standard deviation value is less than a threshold, a block noise region determination unit that determines a corresponding encoded block as a block noise region;
The input video signal of the coding block determined as the non-block noise region is output as it is input, while the input video signal of the coding block determined as the block noise region is compared with the input video signal. And a video signal output unit that outputs a single gradation signal with a small gradation value. In the power consumption reduction apparatus according to claim 1,
The single gradation signal is set as a value common to all coding blocks determined to be a block noise region. In the power consumption reduction device according to claim 2,
The common value is a gradation value that gives a black level. In the power consumption reduction device according to claim 2,
The common value is set to be equal to or smaller than a standard deviation value of each coding block from an average gradation value of each coding block determined to be a block nozzle region. In the power consumption reduction apparatus according to claim 1,
The common value is set to be equal to or smaller than a standard deviation value of the entire coding block from an average gradation value of all coding blocks determined to be a block nozzle region. . The power consumption reduction device according to claim 1 is:
An average value calculation unit for calculating an average gradation value of an input video signal corresponding to each coding block;
The block nozzle area determination unit determines a corresponding encoded block as a block noise area when the average gradation value is less than a threshold value and the standard deviation value is less than a threshold value. In the power consumption reduction apparatus according to claim 1,
The power consumption reduction device, wherein the input video signal is a broadcast wave signal or a streaming signal transmitted in real time. In the power consumption reduction apparatus according to claim 1,
The power consumption reduction apparatus, wherein the input video signal is a playback video signal of a recording medium. A frame memory for storing input video signals;
An area dividing unit for dividing the input video signal accumulated in the frame memory into encoded block units;
A standard deviation calculating unit for calculating a standard deviation value of an input video signal corresponding to each coding block;
When the standard deviation value is less than a threshold, a block noise region determination unit that determines a corresponding encoded block as a block noise region;
The input video signal of the coding block determined as the non-block noise region is output as it is input, while the input video signal of the coding block determined as the block noise region is compared with the input video signal. A video signal output unit that outputs a single gradation signal with a small gradation value,
And a display device to which an input video signal or a single gradation signal is supplied from the video signal output unit. A frame memory for storing input video signals;
An area dividing unit for dividing the input video signal accumulated in the frame memory into encoded block units;
A standard deviation calculating unit for calculating a standard deviation value of an input video signal corresponding to each coding block;
When the standard deviation value is less than a threshold, a block noise region determination unit that determines a corresponding encoded block as a block noise region;
The input video signal of the coding block determined as the non-block noise region is output as it is input, while the input video signal of the coding block determined as the block noise region is compared with the input video signal. And an image signal output unit that outputs a single gradation signal having a small gradation value. A process of dividing the input video signal stored in the frame memory into encoded block units;
Processing for calculating the standard deviation value of the input video signal corresponding to each coding block;
When the standard deviation value is less than a threshold value, a process of determining a corresponding encoded block as a block noise region;
For the input video signal of the coding block determined to be a non-block noise area, processing to output as input,
A process for outputting an input video signal of a coding block determined to be a block noise region by replacing the input video signal with a single gradation signal having a gradation value smaller than that of the input video signal. Power reduction method. On the computer,
A process of dividing the input video signal stored in the frame memory into encoded block units;
Processing for calculating the standard deviation value of the input video signal corresponding to each coding block;
When the standard deviation value is less than a threshold value, a process of determining a corresponding encoded block as a block noise region;
For the input video signal of the coding block determined to be a non-block noise area, processing to output as input,
For an input video signal of an encoded block determined to be a block noise region, a process of outputting a single gradation signal having a gradation value smaller than that of the input video signal is output. Computer program.

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