JP2010139947A - Image signal processing method and image signal processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image signal processing method capable of appropriately correcting afterglow colors of a moving object on a displayed image, and to provide an image signal processing device. <P>SOLUTION: The method comprises: detecting information of a moving amount and information of a moving direction when an object expressed by an input image signal moves on a display screen; calculating an afterglow level generated when the object moves on the display screen, from the information of the moving amount and the afterglow characteristics of a phosphor included in a phosphor layer; specifying a correction object pixel to be corrected in a plurality of display pixels constituting the display screen based on the information of the moving direction; and using the afterglow level as a correction amount and correcting the input image signal corresponding to the correction object pixel based on the correction amount. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image signal processing method and an image signal processing apparatus for correcting afterglow of a moving object in a display image.

  In plasma display panels and liquid crystal display panels, the afterglow characteristics of red, green, and blue phosphors are different from each other, and the afterglow time of red and green tends to be long and the afterglow time of blue tends to be short. For example, when a light emission pulse of the same level with the same time width is applied to each of the red, green, and blue phosphors, as shown in FIG. 1, the red phosphor and the green phosphor are compared with the afterglow characteristics of the blue phosphor. In the afterglow characteristics of the phosphor, the afterglow time becomes long.

  When there is a difference in afterglow characteristics, a color different from the color to be displayed is displayed on a display panel that displays a desired color by additive color mixing of the emission colors of red, green, and blue phosphors. Will be. For example, in the case of a high-contrast image in which a white object is moving on a black background, a yellow afterglow color formed by mixing red and green having a long afterglow time is visually recognized at the boundary between white and black. The afterglow color has the highest luminance near the boundary, and the luminance gradually decreases with distance from the boundary. Since this yellow afterglow color is not visible in the original image, the quality is remarkably deteriorated particularly in the case of a monochrome display image.

In order to cope with this, in the conventional image signal processing apparatus, the yellow afterglow component of the current image is changed according to the luminance of red, green, and blue of the image one frame or one field before the current image to be displayed. Afterglow color correction is performed by adding a blue component to be canceled (see Patent Document 1).
JP 2006-284886 A

  In the conventional image signal processing apparatus, yellow that is visually recognized as an afterglow component is strong in the portion close to the black-and-white boundary, and as shown in FIG. As shown in FIG. 2B, the blue color added as a correction is a constant amount regardless of the distance from the boundary. Accordingly, as shown in FIG. 2 (c), an area A1 in which the correction amount is small and yellow afterglow remains in the vicinity of the boundary, and the correction amount becomes large in the portion away from the boundary, and the corrected blue color is excessive. An area A2 that is recognized is generated, and proper afterglow color correction cannot be performed.

  Therefore, the problem to be solved by the present invention includes the above-described drawbacks as an example, and an image signal processing method and an image signal processing apparatus capable of appropriately performing afterglow color correction on a moving object of a display image. It is an object of the present invention to provide.

  In the image signal processing method according to the first aspect of the present invention, when the display is performed on the display screen of the display device by causing the red, green, and blue phosphor layers to emit light according to the input image signal, the input image is displayed. An image signal processing method for correcting a signal, wherein the object indicated by the input image signal detects movement amount information and movement direction information when moving on the display screen, and the movement amount information and the phosphor The afterglow level generated when the object moves on the display screen is calculated from the afterglow characteristics of the phosphors included in the layer, and based on the movement direction information, a plurality of display pixels constituting the display screen are calculated. A correction target pixel to be corrected is specified, the afterglow level is set as a correction amount, and the input image signal corresponding to the correction target pixel is corrected based on the correction amount.

  The image signal processing device of the present invention according to claim 6 is configured to display the input image when displaying on the display screen of the display device by emitting red, green and blue phosphor layers according to the input image signal. An image signal processing apparatus that corrects a signal, wherein the object indicated by the input image signal moves on the display screen when detecting movement amount information and movement direction information, and the movement amount information The display screen is configured based on calculation means for calculating an afterglow level generated when the object moves on the display screen from the afterglow characteristics of the phosphor included in the phosphor layer, and the moving direction information. Specifying means for specifying a correction target pixel to be corrected among a plurality of display pixels to be corrected, the afterglow level as a correction amount, and the input image signal corresponding to the correction target pixel is corrected based on the correction amount. Is characterized by comprising a correction means for the.

  In the image signal processing method according to the first aspect of the present invention and the image signal processing apparatus according to the sixth aspect of the present invention, the correction amount is calculated from the amount of movement of the moving object and the afterglow characteristic of the phosphor, and the movement of the moving object Since the correction pixel is specified from the direction and the remaining light amount is corrected, it is possible to correct the remaining light amount suitable for the portion where the afterglow occurs. Therefore, for example, yellow afterglow is prevented from remaining in the vicinity of the black-and-white boundary in the direction opposite to the moving direction of the white moving object on the black background, and the corrected excessive blue color is present at a portion away from the boundary. It is also suppressed from being recognized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 shows an image signal processing apparatus according to the present invention. As shown in FIG. 3, the image signal processing apparatus includes a frame memory circuit 1, a degamma conversion circuit 2, a motion detection circuit 3, a motion amount averaging circuit 4, a first motion amount index characteristic conversion circuit 5, a second motion amount index. A characteristic conversion circuit 6, a first exponent characteristic generation circuit 7, a second exponent characteristic generation circuit 8, an exponent characteristic addition circuit 9, a correction amount calculation circuit 10, a yellow subtraction circuit 11, a blue addition circuit 12, and a regamma conversion circuit 13 are provided. ing.

  The frame memory circuit 1 holds one frame of the input image signal as data, delays it for a period of one frame, and outputs it. Since the input image signal includes red, green, and blue components for each of RGB, a capacity for one frame is required for each of RGB. For example, in the case of an input image signal corresponding to a display panel composed of horizontal 1920 pixels × vertical 1080 pixels, 1920 × 1080 = 2073600 pixels corresponds to the memory capacity for one frame, and that one frame is necessary for each RGB. It becomes.

  The degamma conversion circuit 2 performs inverse γ correction on the γ-corrected input image signal data to convert it into linear video data. Since the residual light quantity of the phosphor has an exponential characteristic in the linear video data, the configuration of each circuit in the subsequent stage can be simplified by converting the input data having the γ characteristic into the linear video data.

  The motion detection circuit 3 detects motion information including a motion amount and a motion direction in units of pixels from the difference between the pixel data of the previous frame and the pixel data of the current frame from the frame memory circuit 1. That is, the moving amount and moving direction per frame when the object displayed on the display screen moves on the display screen are detected.

  The motion amount averaging circuit 4 is connected to the output of the motion detection circuit 3 and averages the motion amount output from the motion detection circuit 3. When the amount of motion is detected on a pixel-by-pixel basis, and the difference in the amount of motion between adjacent pixels is large, there is a possibility that the correction amount described later is greatly different between adjacent pixels. In that case, there is a possibility that the distortion is increased in the pattern displayed in the display data after correction, which may be visually disturbing. Therefore, the above-described adverse effects are prevented by averaging the amount of motion among a plurality of adjacent pixels existing around. The motion amount averaged by the motion amount averaging circuit 4 is output to the first motion amount index characteristic conversion circuit 5 and the second motion amount index characteristic conversion circuit 6. As shown in FIG. 4 as adjacent pixels, when averaging the amount of movement of the fifth pixel at the center with nine pixels (first pixel to ninth pixel) of 3 pixels × 3 pixels, Motion amount + motion amount of second pixel + motion amount of third pixel + motion amount of fourth pixel + motion amount of fifth pixel + motion amount of sixth pixel + motion amount of seventh pixel + motion of eighth pixel Amount + motion amount of the ninth pixel) / 9 = average motion amount of the fifth pixel.

  As shown in FIG. 3, a threshold value (motion information difference threshold value) is provided for the difference in motion amount between adjacent pixels, and it is determined that the difference in motion amount is small below the threshold value and the above-described distortion does not occur. The motion amount output from the motion detection circuit 3 may be output as it is, and when the threshold value is exceeded, an averaged motion amount may be output.

  The first motion amount exponent characteristic conversion circuit 5 includes a look-up table that outputs a coefficient K corresponding to the averaged motion amount output from the motion amount averaging circuit 4, and the coefficient K has an exponent characteristic with respect to the motion amount. Have.

  Here, the remaining amount of light with respect to the amount of movement of the object displayed on the display panel has characteristics as shown in FIG. A square indicated by a solid line A in FIG. 5 is the luminance of an actual object moving in the display screen. A characteristic B indicated by an alternate long and short dash line indicates a remaining amount of light when the movement of the object is relatively slow, and a characteristic C indicated by a dotted line indicates the remaining amount of light when the movement of the object is relatively fast. As can be seen from the afterglow characteristics in FIG. 5, the remaining light quantity of the phosphor has an exponential characteristic, and the amount of change varies depending on the movement of the object. That is, the amount of remaining light is small for an object with small movement, and the amount of remaining light is large for an object with large movement. Coefficients K respectively corresponding to this relationship are stored in the first motion amount index characteristic conversion circuit 5, and a small coefficient K is output when the motion amount is small, and a large coefficient K is output when the motion amount is large. Is output.

  Similarly to the first motion amount index characteristic conversion circuit 5, the second motion amount index characteristic conversion circuit 6 looks up to output a coefficient K corresponding to the averaged motion amount output from the motion amount averaging circuit 4. The coefficient K has an exponential characteristic with respect to the amount of motion.

  The exponential characteristics of the first and second motion amount exponential characteristic conversion circuits 5 and 6 are determined corresponding to different phosphor types. For example, in the case of a phosphor layer of a PDP (plasma display panel), not only one type of RGB color but also two or more different types of phosphors are mixed to form a single color phosphor layer. Many. Therefore, in this embodiment, the first and second motion amount exponent characteristic conversion circuits 5 and 6 are provided in parallel. However, two or more motions having different exponent characteristics in accordance with each type of phosphor. A quantity index characteristic conversion circuit may be provided in parallel.

  The first exponential characteristic generation circuit 7 is connected to the outputs of the degamma conversion circuit 2 and the first motion amount exponential characteristic conversion circuit 5. The degamma conversion circuit 2 inputs the amplitude level of the linear video data, that is, the luminance level. The coefficient K is input from the 1 motion amount index characteristic conversion circuit 5. In accordance with the luminance level and the coefficient K, luminance data is generated that takes into account an exponential characteristic that is the remaining light amount of the phosphor. Specifically, the first exponential characteristic generation circuit 7 is configured by an IIR (Infinite Impulse Response) filter, and outputs luminance data (= object data + afterglow data) shown in a frame D of FIG.

  The second exponent characteristic generation circuit 8 is connected to the outputs of the degamma conversion circuit 2 and the second motion amount exponent characteristic conversion circuit 6 and operates in the same manner as the first motion amount exponent characteristic conversion circuit 5. The number of exponent characteristic generation circuits is as many as the number of motion index characteristic conversion circuits.

  The exponent characteristic adding circuit 9 is connected to the outputs of the first and second exponent characteristic generating circuits 7 and 8 and adds the output data of the first and second exponent characteristic generating circuits 7 and 8. If only the first motion amount exponent characteristic conversion circuit 5 and the first exponent characteristic generation circuit 7 are provided, and the second motion amount exponent characteristic conversion circuit 6 and the second exponent characteristic generation circuit 8 are not provided, the exponent There is no need to provide the characteristic addition circuit 9.

  The correction amount calculation circuit 10 is connected to the outputs of the degamma conversion circuit 2 and the exponent characteristic addition circuit 9, and the luminance data output from the exponent characteristic addition circuit 9 is data obtained by adding object data to afterglow data as described above. Therefore, by subtracting the object data component from the output data of the degamma conversion circuit 2 from the output data of the exponent characteristic adding circuit 9, only the afterglow data component is extracted and output. The afterglow data component is the correction amount. In this embodiment, a predetermined threshold value is supplied to the correction amount calculation circuit 10 so that the correction amount is not output at an image signal level equal to or lower than the predetermined threshold value. This is because the afterglow is hardly visually recognized in the low luminance input image data.

  Only the red and green components in the output data of the degamma conversion circuit 2 are supplied to the yellow subtraction circuit 11 together with the output data of the correction amount calculation circuit 10. The yellow subtraction circuit 11 subtracts the output data of the correction amount calculation circuit 10 from the red component and the green component of the output data of the degamma conversion circuit 2 as the correction amount of the red component and the green component constituting the yellow component, and the afterglow component. Correct the yellow. Further, an ON / OFF correction amount adjustment signal is supplied to the yellow subtraction circuit 11 from the correction on / off control circuit 11a, and the yellow subtraction circuit 11 operates when the output data of the degamma conversion circuit 2 includes a yellow component. However, when there is no yellow component at all, it does not operate. The pixel data to be corrected by the yellow subtraction circuit 11 is specified by the correction on / off control circuit 11a based on the motion direction data detected by the motion detection circuit 3. That is, as shown in FIG. 5, the pixel in which afterglow occurs can be specified by the motion direction data, and the pixel is set as a correction target pixel, and the pixel data is set as correction target pixel data.

  Only the blue component in the output data of the degamma conversion circuit 2 is supplied to the blue addition circuit 12 together with the output data of the correction amount calculation circuit 10. The blue addition circuit 12 performs the correction for canceling the yellow color of the afterglow component by adding the output data of the correction amount calculation circuit 10 as the blue component correction amount to the blue component of the output data of the degamma conversion circuit 2. Similarly to the yellow subtracting circuit 11, an ON / OFF correction amount adjustment signal is supplied from the correction on / off control circuit 12 a to the blue adding circuit 12, but the yellow subtracting circuit 11 does not perform any subtraction processing on the yellow component. In this case, the correction amount itself from the correction amount calculation circuit 10 is added, and when a part of the correction amount is subtracted by the yellow subtraction circuit 11, the surplus correction amount is added by the blue addition circuit 12. You can also do it. The pixel data to be corrected by the blue addition circuit 12 is specified by the correction on / off control circuit 12a based on the motion direction data detected by the motion detection circuit 3. That is, as shown in FIG. 5, the pixel in which afterglow occurs can be specified by the motion direction data, and the pixel is set as a correction target pixel, and the pixel data is set as correction target pixel data.

  The re-gamma conversion circuit 13 performs γ correction on the output data (red component and green component) of the yellow subtraction circuit 11 and the output data (blue component) of the blue addition circuit 12 and reconverts it into an image signal to which a γ characteristic is added, and outputs it. To do.

  In the image signal processing apparatus according to the present invention having such a configuration, motion information including a motion amount and a motion direction in units of pixels is detected by the motion detection circuit 3 with respect to input image signal data subjected to γ correction. Further, the motion amount averaging circuit 4 calculates an average motion amount for each pixel. Further, the γ-corrected input image signal data is inversely γ-corrected by the degamma conversion circuit 2 and converted to linear video data.

  Corresponding to the average motion amount calculated by the motion amount averaging circuit 4, a coefficient K is generated by each of the first motion amount index characteristic conversion circuit 5 and the second motion amount index characteristic conversion circuit 6. The coefficient K has an exponential characteristic with respect to the motion amount, and the first motion amount exponent characteristic conversion circuit 5 and the second motion amount index are different from each other in order to correspond to the afterglow characteristics of a plurality of types of phosphors. A coefficient K is generated by the characteristic conversion circuit 6. Further, each coefficient K is supplied to the first exponential characteristic generation circuit 7 and the second exponential characteristic generation circuit 8 to generate luminance data (= object data + afterglow data) that takes into account the exponential characteristic that is the residual light quantity of the phosphor. Is done. Output luminance data of the first exponent characteristic generation circuit 7 and the second exponent characteristic generation circuit 8 are added by the exponent characteristic addition circuit 9 and supplied to the correction amount calculation circuit 10. In the correction amount calculation circuit 10, the object data component is removed from the luminance data, and the afterglow data component is used as the correction amount.

  The yellow correction amount among the correction amounts is supplied to the yellow addition circuit 11, and the blue correction amount among the correction amounts is supplied to the blue addition circuit 12. In the yellow subtraction circuit 11, the yellow correction amount is set to the red and green correction amounts, and the red color and the green correction amount are subtracted from the red component and the green component of the output data of the degamma conversion circuit 2 to correct the afterglow component yellow. Is done. The blue addition circuit 12 performs correction to cancel the afterglow component yellow by adding the blue correction amount and the blue component of the output data of the degamma conversion circuit 2. In this yellow component subtraction and blue component addition correction, a correction pixel is specified from the movement direction of the object.

  By applying γ correction to the output data (red component and green component) of the yellow subtracting circuit 11 and the output data (blue component) of the blue adding circuit 12, an image signal after the afterglow color correction is output.

  As described above, according to the embodiment of the present invention, the correction amount is calculated from the movement amount of the object (moving object) and the afterglow characteristic of the phosphor, the correction pixel is specified from the movement direction of the object, and the remaining light amount is calculated. Since the correction is made, it is possible to correct the amount of remaining light that is suitable for the place where the afterglow occurs. Therefore, as shown in FIG. 2 (c), when a white object is moving in the direction of the arrow on a black background, the yellow afterglow remains in the direction opposite to the direction of the arrow from the boundary. It is possible to suppress the occurrence of A1 and the area A2 in which the corrected excessive blue color is recognized.

  Further, the operation of the above embodiment can also solve the problem that the correction of blue afterglow color is not performed near the boundary portion and the correction blue color is added only at a position away from the boundary portion.

  In the above embodiment, not only the blue component is added, but also the yellow component of the afterglow is subtracted. Therefore, for example, in the conventional afterglow correction in which only the blue component is added, when the portion is a display with extremely low luminance in the original display data, the luminance is reduced by the yellow component of the afterglow and the additional blue component. However, in this embodiment, the afterglow component is subtracted, so that the original extremely low luminance can be displayed as it is, and the luminance linearity is improved. .

  Further, in the above-described embodiment, even if the luminance level corresponding to the correction amount for subtracting the yellow component does not exist in the original data, the afterglow can be prevented by adding the blue component in that case. it can.

  The image signal processing method and the image signal processing apparatus of the present invention can be applied to a television apparatus or a video monitor apparatus using a display panel such as a PDP or a liquid crystal display panel.

It is a figure which shows the afterglow characteristic of the fluorescent substance of red, green, and blue. It is a figure explaining the afterglow color which arises near the boundary of a white moving object in a black background. It is a block diagram which shows the image signal processing apparatus by this invention. It is a figure which shows the motion amount average operation | movement by a motion amount average circuit. It is a figure which shows the afterglow brightness | luminance according to a motion of an object.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Frame memory circuit 2 De-gamma conversion circuit 3 Motion detection circuit 4 Motion amount averaging circuit 5, 6 Motion amount exponent characteristic conversion circuit 7, 8 Exponential property generation circuit 10 Correction amount calculation circuit 11 Yellow subtraction circuit 12 Blue addition circuit 13 Re-gamma conversion circuit

Claims (6)

A video signal processing method for correcting the input video signal when displaying on a display screen of a display device by emitting red, green and blue phosphor layers according to the input video signal,
The object indicated by the input video signal detects movement amount information and movement direction information when moving on the display screen, and the movement amount information and the afterglow characteristics of the phosphor included in the phosphor layer Calculating an afterglow level generated when the object moves on the display screen;
Based on the movement direction information, identify a correction target pixel to be corrected among a plurality of display pixels constituting the display screen,
A video signal processing method, wherein the afterglow level is used as a correction amount, and the input video signal corresponding to the correction target pixel is corrected based on the correction amount.   2. The video signal processing method according to claim 1, wherein the input video signal corresponding to each of red, green, and blue colors of the phosphor layer is corrected based on the correction amount.   3. The video signal processing method according to claim 2, wherein the input video signal is corrected by subtracting a subtraction amount based on the correction amount from an input video signal corresponding to red and green.   3. The video signal processing method according to claim 2, wherein the input video signal is corrected by adding an addition amount based on the correction amount to the input video signal corresponding to blue. For the input video signal corresponding to red and green, the input video signal is corrected by subtracting the subtraction amount based on the correction amount,
The input video signal is corrected by adding an addition amount based on the correction amount to the input video signal corresponding to blue,
The video signal processing method according to claim 2, wherein when the subtraction amount is larger than the correction amount, the difference is set as the addition amount. A video signal processing device that corrects the input video signal when displaying on the display screen of the display device by emitting red, green, and blue phosphor layers according to the input video signal,
Detection means for detecting movement amount information and movement direction information when the object indicated by the input video signal moves on the display screen;
Calculating means for calculating an afterglow level generated when the object moves on the display screen from the movement amount information and an afterglow characteristic of the phosphor included in the phosphor layer;
Identification means for identifying a correction target pixel to be corrected among a plurality of display pixels constituting the display screen based on the movement direction information;
A video signal processing apparatus comprising: a correction unit configured to use the afterglow level as a correction amount and correct the input video signal corresponding to the correction target pixel based on the correction amount.

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