Compression of multiplane images

An apparatus for compressing a multiplane-image (MPI) video, the apparatus comprising:

• at least one processor;
• and
• at least one memory including program code,
• wherein the at least one memory and the program code are configured to, with the at least one processor, cause the apparatus at least to:
• split the MPI video into a first frame sequence and a second frame sequence, the first frame sequence being a sequence of texture frames, with each of the texture frames representing a respective layer of a corresponding multiplane image of the MPI video, the second frame sequence being a sequence of alpha frames, with each of the alpha frames corresponding to a respective one of the texture frames of the first sequence;
• apply a first set of preprocessing operations to convert the first frame sequence into a third frame sequence, the first set including operations according to which a pixel value in a frame of the third frame sequence is determined based on a comparison of a corresponding pixel value of the corresponding alpha frame of the second frame sequence with a first threshold value;
• apply a second set of preprocessing operations to convert the second frame sequence into a fourth frame sequence, the second set including operations according to which a pixel value in a frame of the fourth frame sequence is determined based on a comparison of a corresponding pixel value of a corresponding source image with a second threshold value;
• and
• apply video compression to the second frame sequence and to the fourth frame sequence.

A method of rendering a multiplane-image (MPI) video, the method comprising:

• receiving (i) a first compressed frame sequence having encoded therein a sequence of texture frames, with each of the texture frames representing a respective layer of a corresponding multiplane image of the MPI video, (ii) a second compressed frame sequence having encoded therein a sequence of alpha frames, with each of the alpha frames corresponding to a respective one of the texture frames, and (iii) a compressed sequence of source images;
• applying video decompression to the first compressed frame sequence, the second compressed frame sequence, and the compressed sequence of source images to generate a first uncompressed frame sequence, a second uncompressed frame sequence, and an uncompressed sequence of source images;
• applying a first set of postprocessing operations to the first uncompressed frame sequence to recover the sequence of texture frames;
• applying a second set of postprocessing operations to the second uncompressed frame sequence to recover the sequence of alpha frames;
• and
• combining corresponding pairs of frames from the recovered sequence of texture frames and the recovered sequence of alpha frames to generate a sequence of four-channel frames, with each of the four-channel frames representing a respective layer of a corresponding multiplane image of the MPI video,
• wherein at least one of the first set of postprocessing operations and the second set of postprocessing operations includes one or more operations using the uncompressed sequence of source images.