Abstract: A method encoding successive input data values includes: selecting one of plural complementary sub-ranges of a set of code values according to a current input data value, proportions of the sub-ranges relative to the set of code values defined by a context variable associated with that input data value; assigning the current input data value to a code value within the selected sub-range; modifying the set of code values based on the assigned code value and a size of the selected sub-range; detecting whether the set of code values is less than a predetermined minimum size and if so, successively increasing it until reaching the predetermined minimum size; outputting an encoded data bit in response to each size-increasing operation; modifying the context variable to increase the proportion of the set of code values in the sub-range selected; after encoding a group of input data values, terminating the output data.

Abstract: Image processing apparatus comprises a demosaic processor for receiving a video signal comprising pixel data from an array of photosensors each having a respective color filter so as to restrict the sensitivity of that photosensor to a primary color range selected from a set of three or more primary color ranges, the array being such that the photosensors in alternate rows are sensitive to a first primary color range, and photosensors in intervening rows are sensitive to the other primary color ranges. The pixel data including pixel data from a first subset of the rows sensitive to the first primary color range, the first subset being the same from image to image of the video signal; and pixel data from a second subset of the rows of photosensors sensitive to the other primary color ranges, the second subset changing from image to image of the video signal.

Abstract: A method of pixel interpolation in which a two-dimensional digital filter is arranged so as to interpolate an output pixel from a two-dimensional array of color input pixels by aligning a filtering operation with a detected direction of an image feature at a pixel position to be interpolated comprises detecting image activity within respective color components of a group of input pixels around the pixel position to be interpolated; generating monochromatic test pixels by combining the color components of input pixels in relative proportions dependent upon the detected image activities; detecting the direction of an image feature in a group of the monochromatic test pixels around the pixel position to be interpolated; and interpolating an output pixel using the two-dimensional filter, according to the detected image feature direction.

Abstract: A method of pixel interpolation in which a two-dimensional digital filter is arranged so as to interpolate an output pixel from a two-dimensional array of input pixels comprises detecting the direction of an image feature at a pixel position to be interpolated; applying a shear transformation to the digital filter and/or to the array of input pixels so as to map the operation of the filter to the detected image feature direction in respect of at least a first one of two axes of the two dimensional filter; and applying the digital filter to obtain the output pixels.

Abstract: Image processing apparatus comprises a demosaic processor for receiving a video signal comprising pixel data from an array of photosensors each having a respective color filter so as to restrict the sensitivity of that photosensor to a primary color range selected from a set of three or more primary color ranges, the array being such that the photosensors in alternate rows are sensitive to a first primary color range, and photosensors in intervening rows are sensitive to the other primary color ranges. The pixel data including pixel data from a first subset of the rows sensitive to the first primary color range, the first subset being the same from image to image of the video signal; and pixel data from a second subset of the rows of photosensors sensitive to the other primary color ranges, the second subset changing from image to image of the video signal.

Abstract: A method of pixel interpolation in which a two-dimensional digital filter is arranged so as to interpolate an output pixel from a two-dimensional array of colour input pixels by aligning a filtering operation with a detected direction of an image feature at a pixel position to be interpolated comprises detecting image activity within respective colour components of a group of input pixels around the pixel position to be interpolated; generating monochromatic test pixels by combining the colour components of input pixels in relative proportions dependent upon the detected image activities; detecting the direction of an image feature in a group of the monochromatic test pixels around the pixel position to be interpolated; and interpolating an output pixel using the two-dimensional filter, according to the detected image feature direction.

Abstract: A method of pixel interpolation in which a two-dimensional digital filter is arranged so as to interpolate an output pixel from a two-dimensional array of input pixels comprises detecting the direction of an image feature at a pixel position to be interpolated; applying a shear transformation to the digital filter and/or to the array of input pixels so as to map the operation of the filter to the detected image feature direction in respect of at least a first one of two axes of the two dimensional filter; and applying the digital filter to obtain the output pixels.