Block noise detector and block noise eliminator

A block noise eliminating apparatus for detecting and eliminating, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal, said block noise elimination apparatus comprising:

• signal extracting means for receiving the video signal and extracting only a high frequency component from the video signal;
• absolute value taking means for taking an absolute value of a high frequency component signal outputted from said signal extracting means;
• accumulating/adding means for accumulating/adding an absolute value signal outputted from said absolute value taking means for a predetermined period;
• periodicity detecting means for detecting periodicity of the block noise in accordance with an accumulation/addition result outputted from said accumulating/adding means;
• block boundary determining means for determining a block boundary, where the block noise is generated, from a periodic signal detected by said periodicity detecting means;
• and
• block noise eliminating means for eliminating the block noise with respect to the block boundary.

A block noise eliminating apparatus for detecting and eliminating, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal, said block noise eliminating apparatus comprising:

• vertical block boundary detecting means for receiving the video signal and detecting with respect to the video signal, a vertical block boundary where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;
• horizontal block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;
• block area detecting means for specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary detected in said vertical block boundary detecting means and said horizontal block boundary detecting means, respectively;
• and
• block boundary smoothing means for smoothing the video signal to be inputted in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction specified by said block area detecting means,
• wherein said vertical block boundary detecting means comprises:
• a vertical high-pass filter for extracting a vertical high frequency component of the video signal;
• first absolute value taking means for taking an absolute value of a high frequency component signal outputted from said vertical high-pass filter;
• horizontal accumulating/adding means for accumulating/adding an absolute value signal outputted from said first absolute value taking means in a horizontal direction;
• a first high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said horizontal accumulating/adding means;
• first N-point accumulating/adding means for accumulating/adding a signal outputted from said first high-pass filter on a predetermined N-point basis, where N is a positive integer;
• a first temporal filter for detecting the vertical block noise level of the video signal by extending the signal outputted from said first high-pass filter in a temporal direction;
• first maximum value detecting means for determining a maximum value and a position of the maximum value from among N-piece accumulated/added values determined by said first N-point accumulating/adding means through accumulation/addition;
• and
• first masking means for masking the vertical block noise level detected by said first temporal filter at the position of the maximum value outputted from said first maximum value detecting means, and then determining the vertical block boundary corresponding to the position, and wherein
• said horizontal block boundary detecting means comprises:
• a horizontal high-pass filter for extracting a horizontal high frequency component of the video signal;
• second absolute value taking means for taking an absolute value of a high frequency component signal outputted from said horizontal high-pass filter;
• vertical accumulating/adding means for accumulating/adding an absolute value signal outputted from said second absolute value taking means in a vertical direction;
• a second high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said vertical accumulating/adding means;
• second N-point accumulating/adding means for accumulating/adding a signal outputted from said second high-pass filter on a predetermined N-point basis;
• a second temporal filter for detecting the horizontal block noise level of the video signal by extending the signal outputted from said second high-pass filter in a temporal direction;
• second maximum value detecting means for determining a maximum value and a position of the maximum value from among N-piece accumulated/added values determined by said second N-point accumulating/adding means through accumulation/addition;
• and
• second masking means for masking the horizontal block noise level detected by said second temporal filter at the position of the maximum value outputted from said second maximum value detecting means, and then determining the horizontal block boundary corresponding to the position.

A block noise eliminating apparatus for detecting and eliminating, from a video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal, said block noise eliminating apparatus comprising:

• AD converting means for receiving an analog video signal and then converting the analog video signal into a first digital video signal;
• digital decoding means for receiving a second digital video signal as an encoded digital signal and for decoding and outputting the second video signal including decoded block boundary information;
• a selector for receiving the first digital video signal outputted from said AD converting means and the second digital video signal outputted from said digital decoding means and selectively outputting one of the first and second digital video signals, as the video signal, as is externally instructed;
• vertical block boundary detecting means for receiving the video signal selected by said selector and detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;
• horizontal block boundary detecting means for receiving the video signal selected by said selector and detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated in a longitudinal direction and a horizontal block noise level on a the screen;
• block area detecting means for specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary detected in said vertical block boundary detecting means and said horizontal block boundary detecting means respectively;
• and
• block boundary smoothing means for smoothing the video signal in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction specified by said block area detecting means, wherein
• said vertical block boundary detecting means and said horizontal block boundary detecting means output, to said block area detecting means, the vertical block boundary and the horizontal block boundary, respectively, when said selector selects the first video signal outputted from said AD converting means, and output a block boundary based on the block boundary information outputted from said digital decoding means when said selector selects the second video signal outputted from said digital decoding means.

A block noise eliminating apparatus for detecting and eliminating, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal said block noise eliminating apparatus comprising:

• vertical block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;
• horizontal block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;
• block area detecting means for specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary detected in said vertical block boundary detecting means and said horizontal block boundary detecting means, respectively;
• block boundary smoothing means for smoothing the video signal to be inputted in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction specified by said block area detecting means;
• and
• controlling means for specifying the video signal to be inputted in accordance with the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means, wherein
• said controlling means is operable to display a judgement result of the specification of the video signal on a screen in a predetermined format.

A vertical block boundary detecting apparatus for detecting, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise in a vertical direction caused by decoding the video signal, said vertical block boundary detecting apparatus comprising:

• a vertical high-pass filter for receiving the video signal and extracting a vertical high frequency component of the video signal;
• absolute value taking means for taking an absolute value of a high frequency component signal outputted from said vertical high-pass filter;
• horizontal accumulating/adding means for accumulating/adding an absolute value signal outputted from said absolute value taking means in a horizontal direction;
• a high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said horizontal accumulating/adding means;
• N-point accumulating/adding means for accumulating/adding a signal outputted from said high-pass filter on a predetermined N-point basis, where N is a positive integer;
• a temporal filter for detecting a block noise level of the video signal by extending the signal outputted from said high-pass filter in a temporal direction;
• maximum value detecting means for determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said N-point accumulating/adding means through accumulation/addition;
• and
• masking means for masking the block noise level detected by said temporal filter at the position of the maximum value outputted from said maximum value detecting means, and determining a vertical block boundary corresponding to the position.

A horizontal block boundary detecting apparatus for detecting, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise in a horizontal direction caused by decoding the video signal, said horizontal block boundary detecting apparatus comprising:

• a horizontal high-pass filter for receiving the video signal and extracting a horizontal high frequency component of the video signal;
• absolute value taking means for taking an absolute value of a high frequency component signal outputted from said horizontal high-pass filter;
• vertical accumulating/adding means for accumulating/adding an absolute value signal outputted from said absolute value taking means in a vertical direction;
• a high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said vertical accumulating/adding means;
• N-point accumulating/adding means for accumulating/adding a signal outputted from said high-pass filter on a predetermined N-point basis, where N is a positive integer;
• a temporal filter for detecting a block noise level of the video signal by extending the signal outputted from said high-pass filter in a temporal direction;
• maximum value detecting means for determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said N-point accumulating/adding means through accumulation/addition;
• and
• masking means for masking the block noise level detected by said temporal filter at the position of the maximum value outputted from said maximum value detecting means, and determining a horizontal block boundary corresponding to the position.

A dot clock controlling apparatus for controlling a dot clock to be regenerated in a video processing system in which a digital video signal subjected to lossy encoding on a predetermined image block basis is processed, said dot clock controlling apparatus comprising:

• clock generating means for generating the dot clock used in the video processing system in accordance with a horizontal synchronizing pulse,
• horizontal block boundary detecting means for receiving the video signal and detecting a longitudinal block boundary, where block noise is generated, on a screen with respect to the video signal;
• and
• controlling means for changing a delay of said clock generating means such that the longitudinal block boundary detected by said horizontal block boundary detecting means periodically has a single maximum point,
• wherein said horizontal block boundary detecting means comprises:
• a horizontal high-pass filter for receiving the video signal and extracting a horizontal high frequency component of the video signal;
• absolute value taking means for taking an absolute value of a high frequency component signal outputted from said horizontal high-pass filter;
• vertical accumulating/adding means for accumulating/adding an absolute value signal outputted from said absolute value taking means in a vertical direction;
• a high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said vertical accumulating/adding means;
• and
• N-point accumulating/adding means for accumulating/adding a signal outputted from said high-pass filter on a predetermined N-point basis, where N is a positive integer.

A program recorded on a recording medium, to be run in a computer device for detecting block noise from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

• extracting only a high frequency component from the video signal as an extracted high frequency component signal;
• taking an absolute value of the extracted high frequency component signal as an absolute-value-taken high frequency component signal;
• accumulating/adding the absolute-value-taken high frequency component signal for a predetermined period;
• detecting a periodicity of the block noise in accordance with a result of said accumulating/adding operation;
• and
• determining a block boundary, where the block noise is generated, in accordance with a signal having the periodicity detected by said detecting operation.

A program recorded on a recording medium to be run in a computer device for detecting block noise from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

• detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;
• detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;
• specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary obtained in said detecting as to the lateral direction and said detecting as to the longitudinal direction, respectively;
• and
• smoothing the video signal in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction,
• wherein said detecting as to the lateral direction comprises:
• extracting a vertical high frequency component from the video signal as an extracted high frequency component signal;
• taking an absolute value of the extracted high frequency component signal as an absolute value signal;
• accumulating/adding the absolute value signal in a horizontal direction as an accumulated/added high frequency component signal;
• extracting a high frequency component from the accumulated/added high frequency component signal as a signal;
• accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis where N is a positive integer;
• detecting the vertical block noise level of the video signal by extending the signal outputted in said extracting of the high frequency component in a temporal direction;
• determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said accumulation/addition operation;
• and
• masking the detected vertical block noise level at the position of the maximum value, and determining the vertical block boundary corresponding to the position, and
• wherein said detecting as to the longitudinal direction comprises:
• extracting a horizontal high frequency component of the video signal as an extracted high frequency component signal;
• taking an absolute value of the extracted high frequency component signal as an absolute value signal;
• accumulating/adding the absolute value signal in a vertical direction as an accumulated/added high frequency component signal;
• extracting a high frequency component from the accumulated/added high frequency component signal as a signal;
• accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis;
• detecting the horizontal block noise level of the video signal by extending the signal outputted in said extracting of the high frequency component in a temporal direction;
• determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said accumulation/addition operation;
• and
• masking the detected horizontal block noise level at the position of the maximum value, and determining the horizontal block boundary corresponding to the position.

A program recorded on a recording medium to be run in a computer device for detecting block noise from a video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal said program for comprising:

• converting an analog video signal into a first digital video signal;
• decoding a second digital video signal as a digital-encoded video signal and outputting the second digital video signal including decoded block boundary information;
• selecting one of the first digital video signal outputted in said converting operation and the second digital video signal outputted in said decoding and outputting operation, as the video signal, as is externally instructed;
• detecting a lateral block boundary, where the block noise is generated, on a screen and a lateral block noise level with respect to the video signal outputted in said selecting operation;
• detecting a longitudinal block boundary, where the block noise is generated, on the screen and a longitudinal block noise level with respect to the video signal outputted in said selecting operation;
• specifying a block boundary in both the longitudinal direction and the lateral direction from the lateral block boundary and the longitudinal block boundary obtained in said detecting as to the lateral direction and said detecting as to longitudinal direction selected, respectively;
• and
• smoothing the video signal in a predetermined manner according to the block boundary in both the longitudinal direction and the lateral direction, wherein
• said detecting as to the lateral direction and said detecting as to the longitudinal direction each comprises outputting the block boundary based on the lateral block boundary and the longitudinal block boundary, respectively, for the first digital video signal outputted in said converting operation, and outputting the block boundary based on the decoded block boundary information for the second digital video signal outputted in said decoding and outputting operation.

A program recorded on a recording medium to be run in a computer device for detecting block noise from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

• detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;
• detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;
• specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary obtained in said detecting as to the lateral direction and said detecting as to the longitudinal direction, respectively;
• smoothing the video signal in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction;
• and
• specifying the video signal to be inputted in accordance with the longitudinal and lateral block noise levels detected in said detecting as to longitudinal direction and said detecting as to the lateral directions, respectively, as a judgement result, wherein
• said specifying comprises displaying the judgement result on a screen in a predetermined format.

A program recorded on a recording medium to be run in a computer device for detecting block noise in one of a vertical direction and a horizontal direction from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

• extracting one of a vertical high frequency component and a horizontal high frequency component of the video signal as an extracted high frequency component signal;
• taking an absolute value of the extracted high frequency component signal as an absolute value signal;
• accumulating/adding the absolute value signal in the horizontal direction or the vertical direction as an accumulated/added high frequency component signal;
• extracting a high frequency component from the accumulated/added high frequency component signal as a signal;
• accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis, where N is a positive integer;
• detecting a block noise level of the video signal by extending the signal outputted in said extracting of the high frequency component in a temporal direction;
• determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said accumulating/adding operation;
• and
• masking the detected block noise level at the position of the maximum value, and determining a vertical block boundary or a horizontal block boundary corresponding to the position of the maximum value.

A program recorded on a recording medium to be run in a computer device for controlling a dot clock to be regenerated in a video processing system in which a digital video signal subjected to lossy encoding on a predetermined image block basis is processed, said program comprising:

• receiving the video signal and detecting a block boundary with respect to the video signal, where block noise is generated, in a longitudinal direction on a screen;
• and
• changing a clock delay such that the block boundary detected in said detecting operation periodically has a single maximum point with respect to a clock generating device in which the dot clock used for the video processing system is generated based on a horizontal synchronizing pulse,
• wherein said detecting operation step comprises:
• extracting a horizontal high frequency component of the video signal as an extracted high frequency component signal;
• taking an absolute value of the extracted high frequency component signal as an absolute value signal;
• accumulating/adding the absolute value signal in a vertical direction as an accumulated/added high frequency component signal;
• extracting a high frequency component from the accumulated/added high frequency component signal as a signal;
• and
• accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis, where N is a positive integer.

A block noise eliminating apparatus for detecting and eliminating, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal, said block noise eliminating apparatus comprising:

• vertical block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;
• horizontal block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;
• block area detecting means for specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary detected in said vertical block boundary detecting means and said horizontal block boundary detecting means, respectively;
• block boundary smoothing means for smoothing the video signal to be inputted in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction specified by said block area detecting means;
• picture enhancing means for controlling a picture enhancement level emphasizing an outline part of the video signal according to the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise detected by said vertical block boundary detecting means and
• controlling means for specifying the video signal to be inputted in accordance with the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means, wherein
• said controlling means is operable to display a judgement result of the specification of the video signal on a screen in a predetermined format.

A program recorded on a recording medium to be run in a computer device for detecting block noise from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

• detecting with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;
• detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;
• specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary obtained in said detecting as to the lateral direction and said detecting as to the longitudinal direction, respectively;
• smoothing the video signal in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction;
• controlling a picture enhancement level emphasizing an outline of the video signal according to the longitudinal and lateral block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively;
• and
• specifying the video signal to be inputted in accordance with the longitudinal and lateral block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively, as a judgement result, wherein
• said specifying comprises displaying the judgement result of the video signal on a screen in a predetermined format.