Encoding image data and mask information to be used for matte images and for image and video matting. Image data and mask information for pixels of the image data in a first representation domain are accessed. The mask information defines background pixels and foreground pixels. The image data in the first representation domain is transformed to a second representation domain. Mask information in the second representation domain is determined by using the mask information in the first representation domain. The image data in the second representation domain is masked by setting image data to zero for background pixels as defined by the determined mask information in the second representation domain. The masked image data in the second representation domain is encoded. Decoding the encoded image data by accessing the encoded image data, decoding the masked image data in the second representation domain, and transforming the masked image data in the second representation domain to the first representation domain to obtain the decoded image data.