Apparatus and method for converting between interlaced and progressive scan video
An image processing apparatus generating output image pixels from groups of one or more input image pixels, the groups selected in accordance with an image feature direction in the input image. An interpolator interpolates intermediate pixels between the input image pixels, and a block comparator detects correlation between sets of test blocks of pixels in the input image, which sets are oriented with respect to a current pixel position so that the orientation of a set having the greatest correlation indicates a probable image feature direction applicable to the current pixel position. For at least some sets of test blocks having an orientation with respect to the current pixel position within a predetermined range around a vertical orientation, the test blocks include the input image pixels and intermediate pixels interpolated from the input image pixels. For other sets of test blocks, the test blocks include only the input image pixels.
1. Image processing apparatus in which pixels of an output image are generated from groups of one or more pixels of an input image, the groups being selected in accordance with an image feature direction in the input image, the apparatus comprising:
an interpolator configured to interpolate intermediate pixels between pixels of the input image; and
a block comparator configured to detect correlation between sets of test blocks of pixels in the input image, the sets of test blocks being oriented with respect to a current pixel position so that the orientation of a set having the greatest correlation indicates a probable image feature direction applicable to the current pixel position, wherein,
for a set of test blocks associated with an image feature angle with respect to the current pixel position within a predetermined range around a vertical orientation, the test blocks include pixels of the input image and intermediate pixels interpolated from pixels of the input image; and
for a set of test blocks associated with an image feature angle with respect to the current pixel position outside the predetermined range around the vertical orientation, the test blocks include only pixels of the input image.
2. Apparatus according to claim 1 , in which for all sets of test blocks which have an orientation with respect to the current pixel position within the predetermined range around the vertical orientation, the test blocks include pixels of the input image and intermediate pixels interpolated from pixels of the input image.
3. Apparatus according to claim 1 , in which the interpolator is configured to interpolate the intermediate pixels in respect of subsets of pixels of the input image, each subset being processed separately in response to a pixel within that subset being included within a test block to be tested by the block comparator.
4. Apparatus according to claim 3 , in which each subset comprises one test block of pixels.
5. Apparatus according to claim 1 , in which the size of the test blocks generally increases with increasing angular displacement from the vertical orientation.
6. Vision mixing apparatus comprising image processing apparatus according to claim 1 .
7. Video display apparatus comprising image processing apparatus according to claim 1 .
8. An image processing method in which pixels of an output image are generated from groups of one or more pixels of an input image, the groups being selected in accordance with an image feature direction in the input image, the method comprising the steps of:
interpolating intermediate pixels between pixels of the input image; and
detecting correlations between sets of test blocks of pixels in the input image, the sets of test blocks being oriented with respect to a current pixel position so that the orientation of a set having the greatest correlation indicates a probable image feature direction applicable to the current pixel position, wherein,
for a set of test blocks associated with an image feature angle with respect to the current pixel position within a predetermined range around a vertical orientation, the test blocks include pixels of the input image and intermediate pixels interpolated from pixels of the input image; and
for a set of test blocks associated with an image feature angle with respect to the current pixel position outside the predetermined range around the vertical orientation, the test blocks include only pixels of the input image.
9. A non-transitory computer readable storage medium having stored thereon computer software having program code which, when executed by a computer, is arranged to cause the computer to carry out the method according to claim 8 .