JP5082549B2 - Video signal processing apparatus and video signal processing method - Google Patents

Description

  The present invention relates to a video signal processing apparatus and a video signal processing method. Specifically, when sharpness adjustment is performed on the video signal after removing block noise, the contour adjustment signal should be reduced according to the motion amount detection result and the block noise detection result using the video signal before block noise removal. Thus, it is possible to prevent a side effect of block noise removal from being emphasized and to display a high-quality image.

  In the video signal encoding process, the video signal is blocked in predetermined pixel units, and DCT conversion is performed on each block. The DCT coefficients obtained by performing this DCT transform are zigzag scanned from a low frequency to a high frequency for both the horizontal spatial frequency component and the vertical spatial frequency, and then quantized, so that variable-length encoded data is obtained. Has been generated. In the decoding process of variable-length encoded data, the variable-length encoded data is subjected to inverse quantization processing, inverse DCT conversion processing, and inverse blocking processing, and is returned to the video signal before the encoding processing.

  In such an encoding / decoding process, a truncation error or a rounding error occurs in DCT conversion, or information is thinned out in quantization. For this reason, even if the decoding process is performed, it is impossible to completely return to the video signal before the encoding process, resulting in a video with low image quality with conspicuous block boundaries, that is, video with conspicuous block noise.

  In order to remove such block noise, for example, in the invention of Patent Document 1, it is determined for each block whether or not it is necessary to remove block noise based on the DCT coefficient of each block obtained by DCT transformation. Block noise removal is performed on blocks that are determined to require noise removal.

JP 2000-299859 A

  By the way, when removing block noise, side effects may occur if the noise removal strength is increased. For example, if a grid pattern is included in the video and the grid size approximately matches the block size, the grid pattern will be detected as block noise if the grid position is at the boundary of the block. It is processed so that the pattern of the shape disappears. Further, when the position of the grid is shifted from the position of the block boundary, no block noise is detected, so that the grid pattern is correctly displayed. For this reason, if the noise removal strength is high and the position of the grid fluctuates in the vicinity of the boundary between the blocks, there is a side effect that the grid-like pattern flickers and is displayed.

  Here, when sharpness adjustment is performed using a video signal from which block noise has been removed with a high noise removal strength, if the sharpness amount is set so as to increase the sharpness, As a result, the high-quality video display cannot be performed.

  In addition, when the noise removal strength is lowered so as not to cause the above-mentioned side effects, block noise may remain in the video signal from which block noise has been removed. For this reason, when sharpness adjustment is performed using such a video signal, if the sharpness amount is set so as to increase the sharpness, the remaining block noise is emphasized, and high It will be impossible to display high-quality video.

  Accordingly, the present invention provides a video signal processing apparatus and a video signal processing method capable of performing high-quality video display.

  The concept of the present invention is to detect a motion amount and block noise of a video from a video signal, perform block noise removal of the video signal using the detection result of the block noise, and use the video signal from which the block noise has been removed. When the sharpness adjustment is performed, the sharpness adjustment is weakened according to the detection result of the motion amount and the detection result of the block noise so that the side effect of the block noise removal is not emphasized.

  The video signal processing apparatus according to the present invention includes a motion amount detection unit that detects a motion amount of a video from the video signal, a block noise detection unit that detects block noise from the video signal, and a detection result of the block noise. It has a block noise removal unit that removes block noise, and a sharpness adjustment unit that adjusts the sharpness by adding a contour adjustment signal to the video signal from which the block noise has been removed. The contour adjustment signal is decreased according to the noise detection result.

  The video signal processing method according to the present invention uses a motion amount detection step of detecting a motion amount of a video from the video signal, a block noise detection step of detecting block noise from the video signal, and a detection result of the block noise. It has a noise removal process that removes block noise from the video signal, and a sharpness adjustment process that adjusts the sharpness by adding a contour adjustment signal to the video signal from which block noise has been removed. The contour adjustment signal is decreased according to the detection result of the block noise.

  According to the present invention, the amount of motion and block noise of a video are detected from the video signal, and the contour adjustment added to the video signal from which block noise has been removed is detected according to the motion amount detection result and the block noise detection result. The signal is reduced. For this reason, side effects due to block noise removal and remaining block noise are not emphasized, and high-quality video display can be performed.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a device using a video signal processing device, for example, a television device. The apparatus using the video signal processing apparatus is not limited to the television apparatus, and for example, a recording / reproducing apparatus for recording / reproducing a video signal using a recording medium (magnetic tape, magnetic disk, optical disk, semiconductor memory, etc.). It may be a set top box or the like.

  In FIG. 1, a satellite broadcast antenna 12 of a television apparatus 11 is an antenna that receives digital satellite broadcast, and a received signal RF1 obtained by the satellite broadcast antenna 12 is supplied to a satellite broadcast tuning / demodulation unit 13. Is done. The satellite broadcast tuning / demodulation unit 13 selects a desired channel (frequency) and digitally demodulates the obtained intermediate frequency signal. Further, the transport stream TS1 obtained by digital demodulation is supplied to the demultiplexer 21. In this digital demodulation, demodulation processing corresponding to the modulation method used in satellite broadcasting, such as QPSK demodulation processing, is performed. The operation of the satellite broadcast tuning / demodulation unit 13 is controlled by a control signal CT from a control unit 80 described later.

  The terrestrial broadcast antenna 15 is an antenna for receiving terrestrial broadcasts, and the reception signal RF2 obtained by the terrestrial broadcast antenna 15 is supplied to the terrestrial broadcast channel selection / demodulation unit 16. The terrestrial broadcast channel selection / demodulation unit 16 selects a desired channel and demodulates the obtained intermediate frequency signal. Here, when receiving a terrestrial analog broadcast, the terrestrial broadcast tuning / demodulation unit 16 performs an analog demodulation process on the intermediate frequency signal, converts the obtained video signal into a digital video signal VSb, and outputs a video. The signal is supplied to the switching unit 31 and the obtained audio signal ASb is supplied to the audio switching unit 71. The terrestrial broadcast channel selection / demodulation unit 16 digitally demodulates the intermediate frequency signal when receiving the terrestrial digital broadcast, and supplies the obtained transport stream TS2 to the demultiplexer 21. In this digital demodulation, a demodulation process corresponding to a modulation method used in terrestrial digital broadcasting, such as a QFDM demodulation process, is performed. The operation of the terrestrial broadcast channel selection / demodulation unit 16 is also controlled by a control signal CT from a control unit 80 described later.

  The demultiplexer 21 selects the transport stream TS1 when receiving the digital satellite broadcast, and selects the transport stream TS2 when receiving the terrestrial digital broadcast. Further, the demultiplexer 21 separates the video data DTv, audio data DTa, broadcast data DTd, etc. included in the selected transport stream in a time-division multiplexed manner, and decodes the video data DTv and the audio data DTa. The broadcast data DTd is supplied to the broadcast data processing unit 23.

  The decoder unit 22 decodes the video data DTv and supplies the obtained video signal VSa to the video switching unit 31. The decoder unit 22 decodes the audio data DTa and supplies the obtained audio signal ASa to the audio switching unit 71.

  The broadcast data processing unit 23 generates a control signal CS for performing predetermined processing according to a user operation, for example, EPG (Electric Program Guide) display, and supplies the control signal CS to the signal generation unit 61.

  An external input terminal 28 is connected to the video switching unit 31, and a composite method, a component method, an HDMI (High Definition Multimedia Interface) method, a DVI (Digital Visual Interface) method is used from an external device via the external input terminal 28. The video signal can be input. Further, a signal processing unit 40 is connected to the video switching unit 31, and the video signal supplied to the signal processing unit 40 is transmitted from the video signal VSa supplied from the decoder unit 22 and the terrestrial broadcast tuning / demodulation unit 16. Of the video signal VSb and the video signal VSc supplied via the external input terminal 28. It is assumed that the video signal VSd supplied to the signal processing unit 40 is composed of a luminance signal and a color difference signal. For example, when a video signal is supplied from the external input terminal 28 by a different method, the video switching unit 31 performs a method conversion process.

  The signal processing unit 40 performs various signal processing on the video signal VSd supplied from the video switching unit 31, and supplies the video signal VSe after the signal processing to the synthesis processing unit 62 as, for example, three primary color signals. The configuration and operation of the signal processing unit 40 will be described later.

  The signal generation unit 61 generates an on-screen display video signal VSosc based on a control signal CS supplied from the broadcast data processing unit 23 or a control signal CT from a control unit 80 described later, and supplies it to the synthesis processing unit 62. . For example, based on the control signal CS supplied from the broadcast data processing unit 23 and the control signal CT from the control unit 80, the signal generation unit 61 generates an on-screen display video signal VSosc for performing EPG display, channel display, and the like. Generated and supplied to the synthesis processing unit 62.

  The synthesis processing unit 62 combines the video signal VSe supplied from the signal processing unit 40 with the video signal VSosc for on-screen display supplied from the signal generation unit 61 and supplies the synthesized video signal VSosc to the video output processing unit 63 as a video output signal VSg. To do. Further, when the on-screen display video signal VSosc is synthesized with the video signal VSe, the synthesis processing unit 62 performs a so-called alpha blending process to change the synthesis ratio of the video signal VSe and the synthesis video signal VSf in the video output signal VSg. It can be so.

  The video output processing unit 63 is connected to a display unit 64 configured using a display device such as an LCD (Liquid Crystal Display), a PDP (Plasma Display Panel), an EL (Electro Luminescence), or a cathode ray tube. The video output processing unit 63 generates a display drive signal DRv for driving the display device based on the video output signal VSg and supplies the display drive signal DRv to the display unit 64. For this reason, video can be displayed on the display unit 64. Further, when the video output processing unit 63 supplies a video signal to an external device (not shown), the video output processing unit 63 outputs the video output signal VSg as an output signal Vout having a format corresponding to the external device.

  An external input terminal 28 is connected to the audio switching unit 71, and an audio signal ASc can be input from an external device via the external input terminal 28. In addition, an audio output processing unit 72 is connected to the audio switching unit 71, and the audio signal ASd supplied to the audio output processing unit 72 is replaced with the audio signal ASa supplied from the decoder unit 22, the channel selection / demodulation for terrestrial broadcasting. The audio signal ASb from the unit 16 or the audio signal ASc supplied via the external input terminal 28 is switched.

  An audio output unit 73 configured using a speaker is connected to the audio output processing unit 72. The audio output processing unit 72 performs audio processing such as signal level adjustment, sound quality adjustment, noise removal processing, and the like using the audio signal ASd supplied from the audio switching unit 71, and outputs the audio output signal DRa after audio processing to the audio output unit 73 to perform audio output. Further, when the audio output processing unit 72 supplies an audio signal to an external device (not shown), the audio output processing unit 72 outputs the signal after the audio processing as an output signal Aout having a format corresponding to the external device.

  A user interface unit 81 is connected to the control unit 80. The user interface unit 81 supplies an operation signal PS corresponding to a user operation to the control unit 80, and includes, for example, an operation key and a remote control signal receiving unit.

  The control unit 80 is connected to the above-described units via the bus 85. The control unit 80 generates a control signal CT based on the operation signal PS from the user interface unit 81 and supplies the control signal CT to each unit, thereby controlling the operation of the television device 11 according to the user operation. . For example, when the operation signal PS supplied from the user interface unit 81 indicates that a signal switching operation such as channel switching, broadcast switching, or input switching has been performed, the control unit 80 determines the desired channel or desired channel. The channel selection operation of the satellite broadcast channel selection / demodulation unit 13 and the ground broadcast channel selection / demodulation unit 16 so that the broadcast video / audio or the video / audio supplied from the outside can be presented. The switching operation of the demultiplexer 21, the video switching unit 31, and the audio switching unit 71 is controlled.

  FIG. 2 shows the configuration of the signal processing unit. The motion amount detection unit 41 of the signal processing unit 40 detects the motion amount MV based on, for example, a luminance signal of the video signal VSd, and supplies the detected motion amount to the block noise removal unit 49 and the p sharpness adjustment unit 54. In the detection of the motion amount MV, for example, a motion vector is detected and the motion amount of the motion vector of each pixel detected is used. In addition, in two temporally continuous images, a signal level difference may be determined for each pixel, and the signal level difference may be used as a motion amount.

  The block noise detection unit 48 performs block noise detection using the video signal VSd, generates a noise detection signal ND indicating the position of the block noise, and a detection status signal NL indicating the block noise detection status, and generates the noise detection signal ND. Are supplied to the block noise removing section 49 and the detection status signal NL is supplied to the sharpness adjusting section 54.

  The block noise removing unit 49 performs a block noise removing process on the video signal VSd and supplies the processed video signal VSda to the conversion processing unit 51. The block noise removing unit 49 removes noise from the block boundary indicated by the noise detection signal ND with a removal intensity corresponding to the motion amount MV, thereby making the block noise inconspicuous.

  The conversion processing unit 51 performs a scaler process on the video signal VSda supplied from the block noise removing unit 49, and converts the display signal into a video signal corresponding to the display resolution of the display unit 64 and the resolution of the external device to which the output signal Vout is supplied. . Also, interlace / progressive conversion is performed as necessary. The luminance signal Yda processed by the conversion processing unit 51 is supplied to the contrast adjustment unit 52. The color difference signals Cr and Cb are supplied to the matrix calculation unit 55.

  The contrast adjustment unit 52 corrects the amplitude of the luminance signal Yda to improve blackness and white brightness. Further, the amplitude correction of the luminance signal Yda is performed so that the contrast according to the user setting is obtained. The luminance signal Ydb after the contrast adjustment is supplied to the sharpness adjustment unit 54.

  The sharpness adjustment unit 54 adds a contour adjustment signal to the luminance signal Ydb so that an image with good sharpness is displayed. Further, the contour adjustment signal is generated so that the influence of the noise removal process is not emphasized. The luminance signal Ydc adjusted by the sharpness adjustment unit 54 is supplied to the matrix calculation unit 55.

  The matrix calculation unit 55 performs matrix calculation using the color difference signals Cr and Cb supplied from the conversion processing unit 51 and the luminance signal Ydc supplied from the sharpness adjustment unit 54 to generate and synthesize a video signal VSe that is a three primary color signal. This is supplied to the processing unit 62.

  FIG. 3 shows the configuration of the block noise detection unit 48. The block extraction unit 481 of the block noise detection unit 48 blocks the luminance signal in a predetermined pixel unit, for example, 8 × 1 pixel unit, and generates a pixel signal for each block (hereinafter referred to as “extraction block”) as a detection signal generation unit. 482.

  The detection signal generation unit 482 calculates a signal level difference between adjacent pixels for the pixels of each extraction block. In addition, at the first or last pixel of each extraction block, a signal level difference is calculated from the pixel of the adjacent extraction block. Further, the calculated signal level difference is compared with the threshold value, and when the signal level difference is larger than the threshold value, the count value for the pixel position in the extraction block is counted up by “1”, thereby each pixel in the extraction block. A histogram of count values at positions is created for one screen. When such a histogram is calculated, the count value of the pixel position corresponding to the boundary portion of the block (hereinafter referred to as “encoded block”) when the block encoding process is performed becomes large. Therefore, based on the count value of the histogram Block noise can be detected.

  FIG. 4 shows a histogram generation operation. FIG. 4A illustrates the extracted block GB extracted by the block extracting unit 481 and the boundary portion BL of the encoded block that becomes block noise. For example, the second pixel and the third pixel of the extracted block GB are illustrated. Is a boundary portion BL. Here, as shown in FIG. 4B, when the signal level difference PE between the extracted pixel signal of 8 pixels and the adjacent pixel in the adjacent extracted block is calculated, 2 as shown in FIG. 4C. When the signal level difference PE between the pixel and the third pixel becomes large and this signal level difference is larger than the threshold value LC, the pixel position corresponding to the boundary portion BL is counted up in the histogram shown in FIG. Is done. Further, when the extracted block extracted next is processed in the same manner, the result is as shown in FIGS. 4E to 4G, and the pixel position corresponding to the boundary portion BL is counted up (indicated by hatching). Accordingly, if such processing is performed in the horizontal direction and the vertical direction, the histogram of the count values at each pixel position in the extraction block indicates the boundary portion BL of the encoded block.

  Further, when the block size of the extracted block and the block size of the encoded block are different, for example, the block size of the extracted block is set to 8 × 1 pixel units, and the block size of the encoded block is set to 12 × 8 pixel units. In this case, two pixel positions having a high count value are generated in the histogram.

  FIG. 5 shows a histogram generation operation when the block sizes are different. FIG. 5A illustrates an example of a boundary portion BL between the extracted block GB extracted by the block extracting unit 481 and the encoded block that becomes block noise. Here, for example, when the second pixel and the third pixel of the extraction block GB are the boundary portion BL, the sixth pixel and the seventh pixel are the boundary portion BL in the next extraction block GB. Here, as shown in FIG. 5B, when the signal level difference PE between the extracted pixel signal of 8 pixels and the adjacent pixel in the adjacent extraction block is calculated, 2 as shown in FIG. 5C. When the signal level difference PE between the pixel and the third pixel becomes large and this signal level difference is larger than the threshold value LC, the pixel position corresponding to the boundary portion BL is counted up in the histogram shown in FIG. (Shown with diagonal lines). Further, in the extracted block extracted next, when the signal level difference between the extracted pixel signal of 8 pixels and the adjacent pixel in the adjacent extracted block is calculated as shown in FIG. As shown in FIG. 5F, when the signal level difference PE between the sixth pixel and the seventh pixel becomes large and this signal level difference is larger than the threshold value LC, the histogram shown in FIG. The corresponding pixel position is counted up. When similar processing is performed, the pixel positions corresponding to the boundary portion BL are counted up (indicated by hatching) as shown in (H) to (J) of FIG. Therefore, two pixel positions having a high count value are generated in the histogram.

The detection signal generation unit 482 generates a histogram as described above, and generates a detection status signal NL from the count value of the histogram. Here, when the count value with the largest value is the count value MCT1, the count value with the second largest value is the count value MCT2, and the count value with the third largest value is the count value MCT3, the detection status signal NL is expressed by, for example, Calculate based on (1).
NL = (MCT1 + MCT2-2 × MCT3) / MCT3 (1)

  Here, when the block noise is small, the count values MCT1, MCT2, and MCT3 are small and the difference is small, the value of the detection status signal NL is small. When the block noise is significant, the count value MCT1 is much larger than the value of MCT3. As described above, when the block size of the extracted block is 8 × 1 pixel unit and the block size of the encoded block is 12 × 8 pixel unit, not only the count value MCT1 but also the value of MCT2 Is much larger than the value of MCT3. Therefore, the value of the detection status signal NL is also large.

  The detection signal generation unit 482 supplies the detection status signal NL generated as described above to the sharpness adjustment unit 54. Further, a noise detection signal ND indicating the pixel position having the count value MCT1 is generated and supplied to the block noise removal unit 49. As described above, when the block size of the extraction block is 8 × 1 pixel unit and the block size of the encoding block is 12 × 8 pixel unit, the count values MCT1 and MCT2 are large values. Become. Here, the count values MCT1 and MCT2 are not counted up at the same time, but are counted up periodically. For this reason, if the noise detection signal ND is generated based on the count-up timing of the count values MCT1 and MCT2 and the block extraction timing and the pixel positions that have become the count values MCT1 and MCT2, Even when the block sizes are different, the pixel position where the block noise is generated can be correctly indicated by the noise detection signal ND.

  The block noise removing unit 49 removes block noise from the pixel position indicated by the noise detection signal ND from the block noise detecting unit 48 because the block noise detecting unit 48 detects the pixel position where the block noise occurs. Process. Further, the block noise removal unit 49 adjusts the noise removal strength using the motion amount detected by the motion amount detection unit.

  FIG. 6 shows a configuration of the block noise removing unit 49. The video signal VSd is supplied to the low-pass filter unit 491 and the multiplier 494. The low-pass filter unit 491 performs a filtering process on the video signal VSd, generates a video signal VFa from which a block noise frequency component has been removed, and supplies the video signal VFa to the multiplier 493.

  The coefficient setting unit 492 sets the coefficient αbnr, (1-αbnr) according to the noise detection signal ND and the motion amount MV, and supplies the coefficient αbnr to the multiplier 493 and the coefficient (1-αbnr) to the multiplier 494. .

  The multiplier 493 multiplies the video signal VFa by the coefficient αbnr and supplies the signal “αbnr × VFa” to the adder 495. The multiplier 494 multiplies the video signal VSd by a coefficient (1−αbnr) and supplies the signal “(1−αbnr) × VSd” to the adder 495. The adder 495 adds the signal “αbnr × VFa” supplied from the multiplier 493 and the signal “(1−αbnr) × VSd” supplied from the multiplier 494, and outputs the result as a video signal VSda.

  The coefficient setting unit 492 configured in this manner sets the coefficient αbnr to “0” and outputs the video signal VSd as the video signal VSda when the noise detection signal ND does not indicate the boundary portion. When the noise detection signal ND indicates that the boundary portion is present, the coefficient setting unit 492 sets the coefficient αbnr to a small value when the motion amount MV is small, and the coefficient when the motion amount MV is large. Increase the value of αbnr.

  FIG. 7 illustrates the relationship between the motion amount MV and the coefficient αbnr set by the coefficient setting unit 492. When the amount of movement MV is smaller than the value “Lmva”, the coefficient αbnr is set to the value “LB1” (note that the coefficient (1-αbnr) is “1-LB1”). When the motion amount MV is equal to or greater than the value “Lmva”, the value of the coefficient αbnr is increased as the motion amount MV increases. Furthermore, when the motion amount MV is equal to or greater than the value “Lmvb”, the coefficient αbnr is set to “1” regardless of the value of the motion amount MV (note that the coefficient (1−αbnr) is “0”).

  As described above, when the coefficient αbnr, (1−αbnr) is set according to the motion amount MV, when the motion amount MV is large, the coefficient αbnr increases and the noise removal strength increases, and the block noise can be removed satisfactorily. Also, when the amount of movement MV is small, the coefficient αbnr is small and the noise removal strength is weak. Therefore, for example, when the image is a lattice-like pattern and the motion is small, the position of the lattice fluctuates in the vicinity of the block boundary. In addition, it is possible to reduce the fact that the lattice-like pattern flickers and is displayed. Furthermore, mosquito noise can be effectively reduced.

  FIG. 8 shows the configuration of the sharpness adjustment unit 54. The luminance signal Ydb is supplied to the compensation signal generation unit 541 and the adder 547.

  The compensation signal generation unit 541 performs, for example, a second-order differential process on the luminance signal Ydb, and filters the obtained second-order differential signal with a band-pass filter to remove unnecessary frequency components and generate a compensation signal Yea. . Further, the generated compensation signal Yea is supplied to the multiplier 545.

  The motion amount coefficient conversion unit 542 converts the motion amount MV generated by the motion amount detection unit 41 into a motion amount coefficient Kmv and supplies it to the adjustment amount setting unit 544. The motion amount coefficient conversion unit 542 converts the motion amount coefficient Kmv to a small value when the value of the motion amount MV is small, and converts the motion amount coefficient Kmv to a large value when the value of the motion amount MV is large.

  FIG. 9 illustrates the conversion characteristics of the motion amount coefficient conversion unit 542. When the motion amount MV is smaller than the value “Lmvc”, the motion amount coefficient Kmv is set to the value “Lkm1”. When the motion amount MV is equal to or greater than the value “Lmvc”, the value of the motion amount coefficient Kmv is increased as the motion amount MV increases. Further, when the motion amount MV is equal to or greater than the value “Lmvd”, the motion amount coefficient Kmv is set to the value “Lkm2” regardless of the value of the motion amount MV. When the motion amount MV is greater than or equal to the value “Lmve”, the value of the motion amount coefficient Kmv is increased as the motion amount MV increases. Further, when the motion amount MV is equal to or greater than the value “Lmvf”, the motion amount coefficient Kmv is set to “1” regardless of the value of the motion amount MV.

  The detection status signal coefficient conversion unit 543 converts the detection status signal NL generated by the block noise detection unit 48 into a block detection coefficient Knl and supplies it to the adjustment amount setting unit 544. The detection status signal coefficient conversion unit 543 converts the block detection coefficient Knl to a small value when the value of the detection status signal NL is small, and converts the block detection coefficient Knl to a large value when the value of the detection status signal NL is large.

  FIG. 10 illustrates the conversion characteristics of the detection status signal coefficient conversion unit 543. When the detection status signal NL is smaller than the value “Lnla”, the block detection coefficient Knl is set to the value “Lkn1”. When the detection status signal NL is greater than or equal to the value “Lnla”, the value of the block detection coefficient Knl is increased as the detection status signal NL increases. Further, when the motion amount MV is equal to or greater than the value “Lnlb”, the block detection coefficient Knl is set to “1” regardless of the value of the detection status signal NL.

The adjustment amount setting unit 544 uses the intensity adjustment coefficient αsh and the coring amount CL based on the motion amount coefficient Kmv supplied from the motion amount coefficient conversion unit 542 and the block detection coefficient Knl supplied from the detection status signal coefficient conversion unit 543. And the set intensity adjustment coefficient αsh is supplied to the multiplier 545 and the set coring amount CL is supplied to the coring unit 546, respectively. For example, the intensity adjustment coefficient αsh is set as shown in Equation (2).
αsh = (1−Kmv × Knl) (2)

  The multiplier 545 multiplies the compensation signal Yea by the intensity adjustment coefficient αsh and supplies the compensation signal Yeb as a multiplication result to the coring unit 546. The coring unit 546 is constituted by a clipping circuit, and clips a low level signal including a zero level.

  The coring unit 546 sets the clip level based on the coring amount CL, performs the clipping process on the compensation signal Yeb, and supplies the obtained compensation signal Yec to the adder 547. The adder 547 adds the compensation signal Yec supplied from the coring unit 546 to the luminance signal Ydb, generates a luminance signal Ydc adjusted for sharpness, and supplies the luminance signal Ydc to the matrix calculation unit 55. If the signal level of the compensation signal can be adjusted according to the user setting, the sharpness level can be adjusted to a desired level by the user.

  Here, when the motion amount MV is large, the motion amount coefficient Kmv is large as shown in FIG. Further, when the level of the detection status signal NL is large, the block detection coefficient Knl is also large as shown in FIG. That is, the value of the intensity adjustment coefficient αsh is small when the image is a dirty image with a large motion and conspicuous block noise. In addition, the intensity adjustment coefficient αsh increases when the image is a clear image with little movement and block noise. Furthermore, when the image has a large motion and the block noise is not noticeable, or the image has a small motion and the block noise is conspicuous, the intensity adjustment coefficient αsh is an intermediate value. Therefore, since the sharpness is weak when the value of the intensity adjustment coefficient αsh is small, processing is performed so as not to exacerbate adverse effects and residual block noise components. Further, when the value of the intensity adjustment coefficient αsh is small, the movement is large and the block noise is remarkable. Therefore, the coring unit 546 increases the coring amount CL and compensates for the contour by the noise component or the like. Prevent it from happening.

  If sharpness adjustment is performed in this way, when the amount of motion is large and block noise is significant, the sharpness intensity is weakened, so the side effects due to block noise removal and the remaining block noise are emphasized. Is prevented, and high-quality video display can be performed. In addition, when the amount of motion is small and the block noise is small, the sharpness intensity is not weakened, so that it is possible to display an image with high quality and good sharpness.

  FIG. 11 shows the characteristics of the coring unit 546. The horizontal axis indicates the signal level of the input compensation signal Yeb, and the vertical axis indicates the signal level of the output compensation signal Yec. Here, the characteristic of the coring part 546 when the value of the strength adjustment coefficient αsh is large is shown in FIG. Here, when the signal level of the compensation signal Yeb is a low level within the coring amount CL, the signal level of the compensation signal Yec is “0”, and when the signal level of the compensation signal Yec is equal to or greater than the coring amount CL, The level changes according to the signal level of the compensation signal Yeb. Further, the characteristics of the coring portion when the intensity adjustment coefficient αsh is small are shown in FIG. 11B, and the coring amount CL is set wider than that in FIG.

  As described above, the coring unit 546 is controlled so that the coring amount CL is increased when the value of the intensity adjustment coefficient αsh is small. Therefore, when the amount of motion is large or the block noise is significant, the compensation signal If the Yeb signal level is not high, sharpness adjustment cannot be performed. Therefore, sharpness adjustment can be performed so that the influence of block noise or the like is not emphasized. Also, since the coring amount CL is controlled to be small when the value of the intensity adjustment coefficient αsh is large, sharpness adjustment is performed even for a video portion where the luminance change is small when the amount of motion is small or block noise is not noticeable. It can be carried out.

  By the way, the sharpness adjusting unit 54 shown in FIG. 8 adjusts the sharpness intensity according to the motion amount MV and the detection status signal NL, but performs the sharpness intensity adjustment according to the average luminance level of the video. By doing so, noise (so-called heartbeat noise) whose brightness changes like a heartbeat in a dark scene or the like can be made inconspicuous.

  In this case, the signal processing unit 40 is provided with a luminance measuring unit that measures the average luminance level of the video. For example, assuming that a luminance measurement circuit that measures the average luminance level of an image using the luminance signal Yda is provided in the previous stage of the contrast adjustment unit 52, the average luminance detection signal APL, which is the measurement result of the average luminance level, is supplied to the sharpness adjustment unit 54. Supply.

  FIG. 12 shows the configuration of the sharpness adjustment unit 54a that performs the sharpness intensity adjustment using the average luminance detection signal APL. In FIG. 12, portions corresponding to those in FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The average luminance coefficient conversion unit 548 converts the average luminance detection signal APL into a detection luminance coefficient Kapl and supplies it to the adjustment amount setting unit 544a. The average luminance coefficient conversion unit 548 converts the detected luminance coefficient Kapl to a large value when the average luminance indicated by the average luminance detection signal APL is low, and reduces the detected luminance coefficient Kapl to a small value when the average luminance detection signal APL is large. Convert to

  FIG. 13 illustrates the conversion characteristics of the average luminance coefficient conversion unit 548. When the average luminance detection signal APL is smaller than the value “Lapa”, the detection luminance coefficient Kapl is set to the value “1”. When the average luminance detection signal APL is greater than or equal to the value “Lapa”, the value of the detection luminance coefficient Kapl is decreased as the average luminance detection signal APL increases. Further, when the average luminance detection signal APL is equal to or greater than the value “Lapb”, the detection luminance coefficient Kapl is set to the value “Lka1” regardless of the value of the average luminance detection signal APL.

The adjustment amount setting unit 544a is supplied from the motion amount coefficient Kmv supplied from the motion amount coefficient conversion unit 542, the block detection coefficient Knl supplied from the detection status signal coefficient conversion unit 543, and the average luminance coefficient conversion unit 548. Based on the detected luminance coefficient Kapl, the intensity adjustment coefficient αsh is set and supplied to the multiplier 545 and the coring unit 546. For example, the intensity adjustment coefficient αsh is set as shown in Expression (3).
αsh = (1−Kmv × Knl × Kapl) (3)

  In this way, when the intensity adjustment coefficient αsh is set using the average luminance coefficient, the sharpness level is low in dark scenes, so hard beat noise is not emphasized by sharpness adjustment, and heartbeat noise is reduced. Can be made inconspicuous.

  In the above embodiment, the boundary between vertical blocks is detected and noise removal and sharpness adjustment are performed. However, the difference between adjacent pixels in the vertical direction is calculated using a frame memory or field memory. If block boundaries in the horizontal direction are detected, block noise removal and sharpness adjustment can be performed not only in the horizontal direction but also in the vertical direction.

  Further, in the above embodiment, the coefficients Kmv, Knl, and Kapl are set to values of “1” or less, and the real type calculation is performed. However, the integer type calculation is performed using these coefficients as integer values. If so, the processing can be speeded up. For example, if the calculation is performed with the coefficient set to an integer value in the range of “0 to 255”, it is not necessary to perform an operation taking the decimal point into account, so the processing can be speeded up.

It is a figure which shows the structure of a television apparatus. It is a figure which shows the structure of a signal processing part. It is a figure which shows the structure of a block noise detection part. It is a figure which shows the production | generation operation | movement of a histogram. It is a figure which shows the production | generation operation | movement of a histogram. It is a figure which shows the structure of a block noise removal part. It is a figure which shows the relationship between motion amount MV and coefficient (alpha) bnr. It is a figure which shows the structure of a sharpness adjustment part. It is a figure which shows the conversion characteristic of a motion amount coefficient conversion part. It is a figure which shows the conversion characteristic of a detection condition signal coefficient conversion part. It is a figure which shows the characteristic of a coring part. It is a figure which shows the other structure of a sharpness adjustment part. It is a figure which shows the conversion characteristic of an average luminance coefficient conversion part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Television apparatus, 12 ... Satellite broadcasting antenna, 13 ... Satellite broadcasting channel selection / demodulation part, 15 ... Terrestrial broadcasting antenna, 16 ... Terrestrial broadcasting channel selection / demodulation , 21 ... Demultiplexer, 22 ... Decoder part, 23 ... Broadcast data processing part, 28 ... External input terminal, 31 ... Video switching part, 40 ... Signal processing part, 41 ... Motion amount detection unit, 48 ... Block noise detection unit, 49 ... Block noise removal unit, 51 ... Conversion processing unit, 52 ... Contrast adjustment unit, 54, 54a ... Sharpness adjustment 55, matrix calculation unit, 61 ... signal generation unit, 62 ... synthesis processing unit, 63 ... video output processing unit, 64 ... display unit, 71 ... audio switching unit, 72 ... Audio output processing unit, 73 ... Audio output unit, DESCRIPTION OF SYMBOLS 0 ... Control part, 81 ... User interface part, 85 ... Bus, 441 ... Block extraction part, 442 ... Detection signal generation part, 491 ... Low-pass filter part, 492 .. Coefficient setting unit, 493, 494, 545... Multiplier, 495, 547 ..adder, 541... Compensation signal generation unit, 542... Motion amount coefficient conversion unit, 543. Signal coefficient conversion unit, 544, 544a ... adjustment amount setting unit, 546 ... coring unit, 548 ... average luminance coefficient conversion unit

Claims (5)

A motion amount detector that detects the amount of motion of the video from the video signal;
A block noise detector for detecting block noise from the video signal;
A block noise removing unit that removes block noise of the video signal based on the detection result of the block noise;
A sharpness adjustment unit for adjusting a sharpness by adding a contour adjustment signal to the video signal from which the block noise has been removed;
The sharpness adjustment unit is configured to output the contour adjustment signal to be added to the video signal from which the block noise has been removed according to the detection result of the motion amount detected before the removal of the block noise and the detection result of the block noise. A video signal processing device characterized in that it is reduced. The video signal processing apparatus according to claim 1, wherein the block noise removal unit sets a noise removal strength according to the amount of motion. A luminance level detection unit for detecting an average luminance level of the video from the video signal;
The video signal processing apparatus according to claim 1, wherein the sharpness adjustment unit decreases the contour adjustment signal according to the average luminance level. A luminance level detector for detecting an average luminance level of the video from the video signal;
The video signal processing apparatus according to claim 1, wherein the sharpness adjustment unit adjusts a coring amount of the contour adjustment signal according to the average luminance level. A motion amount detection step of detecting a motion amount of the video from the video signal;
A block noise detection step of detecting block noise from the video signal;
A noise removal step of removing block noise of the video signal using the detection result of the block noise;
A sharpness adjustment step of adjusting the sharpness by adding a contour adjustment signal to the video signal from which the block noise has been removed;
In the sharpness adjustment step, the contour adjustment signal to be added to the video signal from which the block noise has been removed is determined according to the detection result of the motion amount detected before the removal of the block noise and the detection result of the block noise. A video signal processing method comprising reducing the number of video signals.

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