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 video image system having a decoder for video image decompression, the system comprising:
a data storage system;
a processor in the decoder that is configured to interact with the data storage system to execute instructions to:
access 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; and
determine a predicted motion vector with a frame-distance method, wherein the frame-distance method comprises: given a predicted picture area in a first reference frame, a bi-directionally predicted frame of the predicted picture area, and 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, determining a predicted motion vector that 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,
wherein the video image system is configured to utilize direct mode prediction, and
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.