Abstract: The invention pertains to a method for a video encoder to select data from a set of image blocks, each block being associated with a frame, a counter value and a cost, the method comprising: calculating, for a target block from among said set of image blocks, the respective counter values and the respective costs of other blocks from among said set of image blocks, said other blocks being associated with the same frame as the target block or with a previous frame; and selecting from said other blocks a reference block having the lowest cost and counter value, according to predefined criteria. The invention also pertains to a computer program product for carrying out the method, and to a video encoder apparatus.

Abstract: Apparatus 10 for processing image data comprises an input 11 arranged to receive image data representing an image. The image data comprises a luminance component 13 at a first spatial resolution and at least one chrominance component 14 at a second, lower, spatial resolution. An up-sampling unit 18 up-samples the spatial resolution of the at least one chrominance component 14 to form an up-sampled chrominance component. A guided image filter (GIF) 20 filters the up-sampled chrominance component. The guided image filter comprises a radius parameter which determines an extent of the filter around a pixel. A control unit 15 for the guided image filter 20 determines a value of the radius parameter of the guided image filter. The value of the radius parameter is variable for different pixels of the image, or for different regions of pixels of the image. The control unit 15 can analyze the image data to determine the value of the radius parameter.

Abstract: The invention pertains to a method for a video encoder to select data from a set of image blocks, each block being associated with a frame, a counter value and a cost, the method comprising: calculating, for a target block from among said set of image blocks, the respective counter values and the respective costs of other blocks from among said set of image blocks, said other blocks being associated with the same frame as the target block or with a previous frame; and selecting from said other blocks a reference block having the lowest cost and counter value, according to predefined criteria. The invention also pertains to a computer program product for carrying out the method, and to a video encoder apparatus.

Abstract: Apparatus 10 for processing image data comprises an input 11 arranged to receive image data representing an image. The image data comprises a luminance component 13 at a first spatial resolution and at least one chrominance component 14 at a second, lower, spatial resolution. An up-sampling unit 18 up-samples the spatial resolution of the at least one chrominance component 14 to form an up-sampled chrominance component. A guided image filter (GIF) 20 filters the up-sampled chrominance component. The guided image filter comprises a radius parameter which determines an extent of the filter around a pixel. A control unit 15 for the guided image filter 20 determines a value of the radius parameter of the guided image filter. The value of the radius parameter is variable for different pixels of the image, or for different regions of pixels of the image. The control unit 15 can analyse the image data to determine the value of the radius parameter.