Image processing apparatus, image processing method and program
An edge detection unit performs edge detection on a frame of a moving image. A vertical line extraction unit of a block vertical boundary position detection unit extracts a vertical edge having an intensity equal to or lower than a noise determination threshold from edges detected by the edge detection unit. A vertical counter counts a total number of edges extracted by the vertical line extraction unit with respect to each pixel line position of the frame. A block vertical boundary position determination unit determines a pixel line position having a peak of a count value of the vertical counter as a block vertical boundary position. A block horizontal boundary position detection unit performs the same processing as the block vertical boundary position detection unit on a horizontal edge among edges detected by the edge detection unit and detects a block horizontal boundary position.
1 . An image processing apparatus comprising:
an edge detection unit to perform edge detection on a frame of a moving image;
a vertical line extraction unit to extract a vertical edge having an intensity equal to or lower than a noise determination threshold from edges detected by the edge detection unit;
a horizontal line extraction unit to extract a horizontal edge having an intensity equal to or lower than the noise determination threshold from the edges detected by the edge detection unit;
a vertical counter to count a total number of edges extracted by the vertical line extraction unit with respect to each pixel line position of the frame;
a horizontal counter to count a total number of edges extracted by the horizontal line extraction unit with respect to each pixel row position of the frame; and
a block boundary position determination unit to determine a pixel line position having a peak of a count value of the vertical counter as a block vertical boundary position and determine a pixel row position having a peak of a count value of the horizontal counter as a block horizontal boundary position.
2 . The image processing apparatus according to claim 1 , further comprising:
a vertical count value adding unit to add count values of the vertical counter with respect to a corresponding pixel line position of a plurality of frames; and
a horizontal count value adding unit to add count values of the horizontal counter with respect to a corresponding pixel row position of the plurality of frames, wherein
the block boundary position determination unit determines a pixel line position having a peak of a count value obtained by the vertical count value adding unit as the block vertical boundary position and determines a pixel row position having a peak of a count value obtained by the horizontal count value adding unit as the block horizontal boundary position.
3 . The image processing apparatus according to claim 1 , further comprising:
a periodicity determination unit to determine presence or absence of periodicity of peaks of a count value in each pixel line position and presence or absence of periodicity of peaks of a count value in each pixel row position; and
a noise determination threshold control unit to, if the periodicity determination unit determines that periodicity is present, set a higher noise determination threshold than a current noise determination threshold for a pixel position at a period boundary and set a lower noise determination threshold than the current noise determination threshold for another pixel position and supply the noise determination thresholds for use in processing of a subsequent frame by the vertical line extraction unit and the horizontal line extraction unit.
4 . The image processing apparatus according to claim 2 , further comprising:
a periodicity determination unit to determine presence or absence of periodicity of peaks of a count value in each pixel line position and presence or absence of periodicity of peaks of a count value in each pixel row position; and
a noise determination threshold control unit to, if the periodicity determination unit determines that periodicity is present, set a higher noise determination threshold than a current noise determination threshold for a pixel position at a period boundary and set a lower noise determination threshold than the current noise determination threshold for another pixel position and supply the noise determination thresholds for use in processing of a subsequent frame by the vertical line extraction unit and the horizontal line extraction unit.
5 . The image processing apparatus according to claim 3 , wherein
the periodicity determination unit divides the frame into a plurality of areas in at least one of a vertical direction and a horizontal direction and determines presence or absence of the periodicity with respect to each area.
6 . The image processing apparatus according to claim 4 , wherein
the periodicity determination unit divides the frame into a plurality of areas in at least one of a vertical direction and a horizontal direction and determines presence or absence of the periodicity with respect to each area.
7 . The image processing apparatus according to claim 1 , further comprising:
a sharpening processing unit to perform sharpening processing on the frame of the moving image, wherein
the sharpening processing unit performs sharpening processing at a lower level on a part determined as a block boundary position by the block boundary position determination unit than on another part.
8 . The image processing apparatus according to claim 2 , further comprising:
a sharpening processing unit to perform sharpening processing on the frame of the moving image, wherein
the sharpening processing unit performs sharpening processing at a lower level on a part determined as a block boundary position by the block boundary position determination unit than on another part.
9 . The image processing apparatus according to claim 3 , further comprising:
a sharpening processing unit to perform sharpening processing on the frame of the moving image, wherein
the sharpening processing unit performs sharpening processing at a lower level on a part determined as a block boundary position by the block boundary position determination unit than on another part.
10 . The image processing apparatus according to claim 4 , further comprising:
a sharpening processing unit to perform sharpening processing on the frame of the moving image, wherein
the sharpening processing unit performs sharpening processing at a lower level on a part determined as a block boundary position by the block boundary position determination unit than on another part.
11 . The image processing apparatus according to claim 5 , further comprising:
a sharpening processing unit to perform sharpening processing on the frame of the moving image, wherein
the sharpening processing unit performs sharpening processing at a lower level on a part determined as a block boundary position by the block boundary position determination unit than on another part.
12 . The image processing apparatus according to claim 6 , further comprising:
a sharpening processing unit to perform sharpening processing on the frame of the moving image, wherein
the sharpening processing unit performs sharpening processing at a lower level on a part determined as a block boundary position by the block boundary position determination unit than on another part.
13 . An image processing method comprising:
performing edge detection on a frame of a moving image;
extracting a vertical edge having an intensity equal to or lower than a noise determination threshold from edges detected by the edge detection;
extracting a horizontal edge having an intensity equal to or lower than the noise determination threshold from the edges detected by the edge detection;
counting a total number of edges extracted by the vertical edge extraction with respect to each pixel line position of the frame;
counting a total number of edges extracted by the horizontal edge extraction with respect to each pixel row position of the frame; and
determining a block boundary position by determining a pixel line position having a peak of a count value obtained by the vertical counting as a block vertical boundary position and determining a pixel row position having a peak of a count value obtained by the horizontal counting as a block horizontal boundary position.
14 . A program causing a computer to implement a method comprising:
performing edge detection on a frame of a moving image;
extracting a vertical edge having an intensity equal to or lower than a noise determination threshold from edges detected by the edge detection;
extracting a horizontal edge having an intensity equal to or lower than the noise determination threshold from the edges detected by the edge detection;
counting a total number of edges extracted by the vertical edge extraction with respect to each pixel line position of the frame;
counting a total number of edges extracted by the horizontal edge extraction with respect to each pixel row position of the frame; and
determining a block boundary position by determining a pixel line position having a peak of a count value obtained by the vertical counting as a block vertical boundary position and determining a pixel row position having a peak of a count value obtained by the horizontal counting as a block horizontal boundary position.