Patent ID: 8072541

Claim:
A signal processing apparatus for converting interlaced 4:2:2-format video signals including a luminance component and two chroma components into interlaced 4:2:0 format video signals, comprising: a first downsampling unit configured to apply vertical-direction filtering to pixels in a first chroma field of the interlaced 4:2:2-format video signals by use of a first downsampling low-pass filter and to downsample by a ratio of 2:1 to produce a first chroma field of the interlaced 4:2:0-format video signals; and a second downsampling unit configured to apply vertical-direction filtering to pixels in a second chroma field of the interlaced 4:2:2-format video signals by use of a second downsampling low-pass filter obtained by reversing an order of coefficients of the first downsampling low-pass filter and to downsample by a ratio of 2:1 to produce a second chroma field of the interlaced 4:2:0-format video signals, wherein the first downsampling low-pass filter has such a group delay that a modulo-1 remainder of the group delay at frequency Ï‰=0 is substantially equal to 0.25, wherein the first downsampling low-pass filter is designed together with an associated upsampling low-pass filter such that the first downsampling low-pass filter and the upsampling low-pass filter satisfy perfect reconstruction filter bank condition within a predetermined error tolerance range, and such that a sum of the group delay of the first downsampling low-pass filter and a group delay of a normalized filter obtained by making a sum of all coefficients of the upsampling low-pass filter equal to 1 is substantially equal to an integer number at frequency Ï‰=0 within a predetermined error tolerance range.