Patent ID: 6055339
Filing Date: 2000-04-25
Classification: H04N

Abstract:
Video data compression apparatus comprising:means for frequency separating input video data into one or more primary components, each representing a range of spatial frequency content within said input video data, using M frequency separating stages and a plurality of secondary components, each representing a range of spatial frequency content within said input video data, using N frequency separating stages, N being greater than M; anda quantizer for quantizing each of said primary components with a primary quantization step width Q.sub.1, and for quantizing each of said secondary components with a secondary quantization step width Q.sub.2, where Q.sub.1 and Q.sub.2 are substantially given by:Q.sub.1 =K.sub.1 /R(f.sub.1) and Q.sub.2 =K.sub.2 /R(f.sub.2),withf.sub.1 =a spatial frequency representative of that primary component being quantized,R(f.sub.1)=relative human visual responsiveness at the spatial frequency f.sub.1,f.sub.2 =a spatial frequency representative of that secondary component being quantized,R(f.sub.2)=relative human visual responsiveness at the spatial frequency f.sub.2, andK.sub.1 and K.sub.2 are constants with K.sub.1 >K.sub.2.