Interpolation of video compression frames
Coding techniques for a video image compression system involve improving an image quality of a sequence of two or more bi-directionally predicted intermediate frames, where each of the frames includes multiple pixels. One method involves determining a brightness value of at least one pixel of each bi-directionally predicted intermediate frame in the sequence as an equal average of brightness values of pixels in non-bidirectionally predicted frames bracketing the sequence of bi-directionally predicted intermediate frames. The brightness values of the pixels in at least one of the non-bidirectionally predicted frames is converted from a non-linear representation.
1. A method for video image decompression, the method including:
providing a sequence of predicted and bi-directionally predicted frames each comprising pixel values arranged in picture areas, wherein at least one of the picture areas in at least one of the bi-directionally predicted frames is predicted from picture areas in one or more reference frames using direct mode prediction;
determining, with at least one processor, a predicted motion vector with a frame-distance method, wherein the frame-distance method comprises:
given (1) a predicted picture area in a first reference frame, (2) a bi-directionally predicted frame of the predicted picture area, and (3) at least one motion vector between the predicted picture area in the first reference frame and a co-locating picture area in a second reference frame, the predicted motion vector is linearly proportional to the at least one motion vector and a distance between the bi-directionally predicted frame of the predicted picture area and at least one of the first or second reference frames; and
utilizing direct mode prediction,
wherein both the first and second reference frames are in a display order that is prior to a display order of the bi-directionally predicted frame of the predicted picture area.