Patent ID: 6026190
Filing Date: 2000-02-15
Classification: H04N

Abstract:
A computer-implemented method for encoding image signals, comprising the steps of:(a) receiving an image signal comprising a video frame of a plurality of video frames;(b) selecting a strength S of a variable low-pass filter means having a variable strength, wherein S is selected in accordance with a predetermined target bitstream size, with the size of an encoded bitstream of a previous video frame of the plurality of video frames, and with a quantization level;(c) applying the low-pass filter means at strength S to the image signal; and(d) encoding the filtered image signal to provide an encoded bitstream representative of the current image signal, said encoding comprising the steps of:(1) performing a discrete cosine transform on the image signal to provide a transformed image signal;(2) quantizing the transformed image signal at the quantization level; and(3) run-length encoding the quantized transformed image signal to provide the encoded bitstream; and(4) determining the quantization level before the quantizing of step (d)(2) in accordance with the predetermined target bitstream size and with the size of the encoded bitstream of the previous image signal.