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Re: comb filter

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In Reply to: comb filter posted by kj on January 31, 2001 at 17:18:35:

Firstly, all but the earliest Comb filters are digital. They split the Black and White information from the Color sub- carrier information to produce an S- Video signal.
2 Line or 2D Comb filtering compares 2 lines in an adjacent field, 3D or 3 line Comb filters compare lines from the next field with additional delay. Each has advantages and disadvantages depending on the picture content.
Some adaptive comb filters are better than others- 3 line comb filters shouldbe capable of better resolution but may produce unwanted artifacts.
I hope this helps-

Follow Ups:

Re: comb filter kj 00:53:22 02/05/01 (2)
yes it does help GL. thanks a bunch. so when i see ads that indicate the tv has a digital comb filter then it is either 2 or 3 line?? in other words there is no 1-line comb filter correct? also how does a
3-line comb filter differ from 3DY/C filter or is there a difference??

thanks again,
kj
- Re: comb filter GL 02:11:35 02/05/01 (1)
  A 3 line comb filter is not the same as a 3D Y/C (Y=Luminance C=Chrominance)comb filter.
  The link below explains all of the different comb filters, it is technical but has lots of useful information which would help you decipher manufacturers' specs for their TV's.
  Genuine 3D digital comb filters offer the best performance currently available.
  Here is a summary of the performance of the various filters with test signals:
  Technology What to Look For :
  Simple Analog Filters:
  Limited luminance and color resolution. Cross color effects when observing higher frequencies in the multiburst pattern, AVS frame 50816.
  Analog Line Comb Filters, Glass or CCD:
  Problems listed above are corrected. Hanging dots appear on the horizontal borders between vertical color transitions at the base of the SMPTE color bars, AVS Frame 50815. Dots along the vertical edges of the color bars are present.
  Digital 2-D Adaptive Y/C Separation Filter:
  The 'hanging dots' at the base of the SMPTE color bars are eliminated. The dots on the vertical edges of the color bars remain. Cross-color effects will still be seen on closely spaced diagonal lines, AVS Frame 50828. Cross-luminance dots in the background of Frames 13710-13740 will be improved over the analog line comb filters.
  Digital 2-D Adaptive Y/C Separation Filter:
  Enhanced 'Mitsubishi' Type This version of the 2-D Adaptive Y/C Filter will eliminate the hanging dots on the vertical edges of the color bars, AVS Frame 50815
  Digital 3-D Motion Adaptive Y/C Separation Filter:
  No cross-luminance or cross-color effects should be seen on static (not still) images. Dot crawl should be eliminated in the blue triangle on AVS frames 18612-18770 in play mode.
  - Comb Filters explained
  - Re: comb filter kj 12:52:45 02/06/01 (0)
    GL THANKS a billion!!! this is just the type of technical detail that i like. i may not understnad everything, but it more than satisfies my curious appetite!
    kj

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