A method for generating alpha channel information related to a person, the method may include generating the alpha channel information related to the person by an alpha channel neural network; wherein the alpha channel machine learning process is trained using ground truth alpha channel information that is associated with background information; wherein the ground-truth alpha channel information is generated by: obtaining input images of the person; wherein each image comprises the person and an arbitrary background; repeating, for each input image of the input images, converting the input image, by a portrait matting predictor, to (a) a first colored background image that comprises the person and a background of a first color, and (b) a second colored background image that comprises the person and a background of a second color; wherein the first color differs from the second color.