Guided image filtering for image content

摘要

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.