JP2006041776A - Video signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize smooth correction even in case of intensive correction by suppressing variation in an outline correction amount for every frame, and to suppress flickering variation in luminance at the outline part. <P>SOLUTION: The video signal processor comprises a section 1 for emphasizing the outline of an input video signal, a section 2 performing orthogonal conversion of the output from the outline emphasizing section 1 into a frequency coordinate region, a temporal LPF 3 for suppressing temporal variation in the output from the orthogonal converting section 2, and an inverse orthogonal converting section 4 for converting the output from the temporal LPF 3 into a time-axis coordinate region. Flickering variation in luminance of a moving video can be suppressed without having any effect on a still image by suppressing variation between frames for a signal subjected to outline emphasis or an outline emphasis component. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a video signal processing device mounted on a video display device, a video recording device, or the like.

  In recent years, video display devices and video recording devices have been digitized, and higher definition images have been demanded. An example of a video signal processing apparatus that enhances the contour in order to improve the fineness of the video signal is disclosed in Patent Document 1. FIG. 4 shows a block diagram of a video signal processing apparatus using such a system. In FIG. 4, 11 is a correction signal calculation unit, 12 is an enhancement component calculation unit, 13 is an intermediate value calculation unit, 14 is a level correction unit, and 15 is a comparison / correction unit.

  In the conventional video signal processing apparatus configured as described above, the correction signal calculation unit 11 provides a correction pixel between each of the current pixel and the next pixel at a position k away from the current pixel and the next pixel. Further, the data amount of the correction pixel on the current pixel side is obtained based on the data amount of the current pixel and the previous pixel, and the data amount of the correction pixel on the next pixel side is obtained based on the data amount of the next pixel and the next pixel. The level correction unit 14 performs level correction on the data amount of the correction pixel thus obtained based on the edge enhancement component obtained by the enhancement component calculation unit 12. Further, in the comparison / correction unit 15, the data amount of the correction pixel corrected by the level correction unit 14 is within the range between the current pixel data amount and the intermediate data amount of the current pixel and the next pixel given from the intermediate value calculation unit 13. Alternatively, the correction is performed so that the intermediate data amount and the data amount of the next pixel are within the range.

For example, Patent Document 1 is known as prior art document information relating to this application.
JP 2001-273491 A

  However, in such a video signal processing apparatus, if the correction is made strongly to increase the fineness, the correction amount may change greatly depending on the relationship between the correction pixel and the preceding and following pixels, and the smoothness of the correction may be lost. At this time, while the effect of improving the definition can be obtained in the still image part, especially in the moving image part where the outline of the display image moves, the correction amount is greatly changed for each frame because the smoothness of the correction is lost. The brightness at the contour changed to flicker. This leads to a reduction in image quality, and in order to prevent this reduction in quality, there is a problem in that it is not possible to perform strong edge enhancement, and it is necessary to weaken the correction, resulting in a smaller effect.

  An object of the present invention is to solve such problems and suppress flicker-like luminance changes at the contour portion.

  In order to achieve the above object, a video signal processing apparatus according to claim 1 of the present invention includes a contour emphasizing unit that emphasizes the contour of an input video signal, and an orthogonal that orthogonally transforms the output of the contour emphasizing unit into a frequency coordinate region. It comprises a transform unit, a temporal LPF that suppresses temporal changes in the output of the orthogonal transform unit, and an inverse orthogonal transform unit that performs inverse orthogonal transform of the output of the temporal LPF to the time axis coordinate region.

  According to a second aspect of the present invention, there is provided an image signal processing apparatus comprising: an amplitude detecting unit that detects an amplitude of an input video signal; an outline emphasizing unit that enhances an outline of the input video signal; and an output of the contour emphasizing unit. Is orthogonally transformed to the frequency coordinate region, the temporal LPF that suppresses temporal changes in the output of the orthogonal transformation unit according to the detection result of the amplitude detector, and the output of the temporal LPF is inversely orthogonal to the time axis coordinate region It is comprised from the inverse orthogonal transformation part to convert.

  Furthermore, the video signal processing apparatus according to claim 3 of the present invention includes an amplitude detector that detects the amplitude of the input video signal, an edge enhancement component generator that generates an edge enhancement component of the input video signal, and an outline. An orthogonal transform unit that orthogonally transforms the output of the enhancement component generation unit into the frequency coordinate region, a temporal LPF that suppresses temporal changes in the output of the orthogonal transform unit according to the detection result of the amplitude detection unit, and the temporal LP output. It comprises an inverse orthogonal transform unit that converts to an axial coordinate region, a delay unit that delays an input video signal, and an adder that adds the output of the inverse orthogonal transform unit and the output of the delay unit.

  According to the video signal processing device of the present invention, flicker-like luminance change in a moving image without affecting a still image by suppressing a change between frames with respect to an edge-enhanced signal or an edge enhancement component. The effect which suppresses is acquired.

  A video signal processing apparatus according to an embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a block diagram of a video signal processing apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a contour emphasizing unit that emphasizes the contour of an input video signal. Here, for example, a filtering process that adds a second-order differential signal is used. Reference numeral 2 denotes an orthogonal transform unit that transforms the output signal of the contour emphasizing unit 1 into a frequency coordinate region. The orthogonal transform unit 2 can be realized by, for example, dividing field image data into a plurality of blocks and performing discrete Fourier transform, discrete cosine transform, Hadamard transform, or the like.

  Reference numeral 3 denotes a temporal LPF, which performs low-pass processing on the output of the orthogonal transform unit 2 so as to suppress a change between frames of the video signal. For example, this is realized by averaging the coefficients of the respective frequency components using data orthogonally transformed by blocks at the same positions in the (k) frame and the (k + 1) frame. Reference numeral 4 denotes an inverse orthogonal transform unit, which converts the output of the temporal LPF 3 into a video signal in the time axis coordinate region by performing inverse orthogonal transform. The inverse orthogonal transform unit 4 performs inverse transform when performing orthogonal transform such as inverse discrete Fourier transform, inverse discrete cosine transform, and inverse Hadamard transform.

  That is, the contour emphasis unit 1 emphasizes the contour of the input video signal, the orthogonal transform unit 2 orthogonally transforms the output of the contour emphasis unit 1 to the frequency coordinate region, and the temporal LPF 3 temporally outputs the orthogonal transform unit 2. In the inverse orthogonal transform unit 4, the output of the temporal LPF 3 is subjected to inverse orthogonal transform to the time axis coordinate region.

  In such a video signal processing apparatus, the change in the frequency component of the video signal with the contour emphasis is suppressed between frames, thereby suppressing the flicker-like luminance change at the contour portion due to the contour emphasis in the moving image. In addition, since there is no frequency component change between frames in a still image, there is no influence by the temporal LPF 3 and contour enhancement is performed. As a result, the quality of the image with enhanced outline can be improved and the outline can be enhanced more strongly, and an image with improved definition can be realized.

  FIG. 2 shows an example of a block diagram of a video signal processing apparatus according to another embodiment of the present invention. Here, in FIG. 2, the same blocks as those in FIG.

  In FIG. 2, reference numeral 5 denotes an amplitude detector that detects the amplitude of the input video signal. This is detected, for example, by comparing the luminance data in the peripheral area including the detection pixel and determining the difference between the maximum value luminance and the minimum value luminance. The amplitude value detected by the amplitude detector 5 is sent to the temporal LPF 6. The temporal LPF 6 performs low-pass processing on the output of the orthogonal transform unit 2 so as to suppress changes between frames. At this time, the filter coefficient of the temporal LPF 6 is changed according to the amplitude value detected by the amplitude detector 5. The larger the amplitude value is, the lower the cutoff frequency of the LPF is. When the amplitude value is small, the cutoff frequency is increased, so that the change of the frequency component can be suppressed only in the large amplitude portion in the moving image portion where the flicker-like luminance change is conspicuous. Flicker-like luminance change can be effectively suppressed.

  FIG. 3 shows an example of a block diagram of a video signal processing apparatus according to another embodiment of the present invention. Here, in FIG. 3, the same blocks as those in FIG. 1 and FIG.

  In FIG. 3, reference numeral 7 denotes an outline emphasis component generator. The contour emphasis component generation unit 7 is configured by a filter that allows passage of a secondary differential signal, for example. The contour emphasizing component generated by the contour emphasizing component generating unit 7 is converted into a frequency coordinate region by the orthogonal transforming unit 2, and the change between frames is suppressed by the temporal LPF 6 according to the detection result by the amplitude detecting unit 5. The The output from the temporal LPF 6 is converted again into the time axis coordinate region by the inverse orthogonal transform unit 4 and then added by the adder 9 with the input video signal delayed by the delay adjustment unit 8.

  With these processes, it is possible to suppress a change in the contour enhancement component between frames in the moving image portion in accordance with the amplitude of the input video signal, and to suppress a flicker-like luminance change due to the contour enhancement. Therefore, the image quality can be improved and the emphasis can be enhanced more strongly, so that the definition can be improved.

  As is apparent from the above description, according to the present invention, flickering in a moving image is prevented without affecting a still image by suppressing a change between frames with respect to a signal or contour emphasizing component subjected to contour emphasis. It is an invention that can suppress a change in luminance and is useful for a video signal processing apparatus.

1 is a block diagram of a video signal processing apparatus according to an embodiment of the present invention. Block diagram of a video signal processing apparatus according to another embodiment of the present invention. Block diagram of a video signal processing apparatus according to another embodiment of the present invention. Block diagram of a conventional video signal processing device

Explanation of symbols

1 Outline enhancement unit 2 Orthogonal transformation unit 3, 6 Temporal LPF
4 Inverse orthogonal transform unit 5 Amplitude detection unit 7 Outline enhancement component generation unit 8 Delay adjustment unit 9 Addition unit

Claims (3)

A contour emphasizing unit that enhances the contour of the input video signal, an orthogonal transform unit that orthogonally transforms the output of the contour emphasizing unit into a frequency coordinate region, a temporal LPF that suppresses temporal changes in the output of the orthogonal transform unit, A video signal processing apparatus comprising: an inverse orthogonal transform unit configured to inverse orthogonally transform the output of the temporal LPF into a time axis coordinate region. An amplitude detection unit that detects the amplitude of the input video signal, a contour enhancement unit that enhances the contour of the input video signal, an orthogonal transformation unit that orthogonally transforms the output of the contour enhancement unit into a frequency coordinate region, and the amplitude A temporal LPF that suppresses temporal changes in the output of the orthogonal transform unit according to a detection result of the detection unit, and an inverse orthogonal transform unit that performs inverse orthogonal transform of the output of the temporal LPF to a time axis coordinate region. A characteristic video signal processing apparatus. An amplitude detector that detects the amplitude of the input video signal, an edge enhancement component generator that generates an edge enhancement component of the input video signal, and an orthogonal that transforms the output of the edge enhancement component generator into a frequency coordinate region A transform unit, a temporal LPF that suppresses temporal changes in the output of the orthogonal transform unit in accordance with a detection result of the amplitude detector, and an inverse orthogonal transform unit that performs inverse orthogonal transform of the output of the temporal LPF to a time axis coordinate region And a delay unit that delays the input video signal, and an adder that adds the output of the inverse orthogonal transform unit and the output of the delay unit.

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