Food for thought – colour decoding

[Fasola_Jan]

According to this:

http://www.ee.washington.edu/conselec/CE/kuhn/ntsc/95x4.htm

PAL and NTSC colour representation
is slightly different (CIE diagram).

I think that capture cards are compensating this,
but what with DVD decoding?

Or am I totally crazy (after reading few pages about
phase alternating line,
interlaced colour representation in frame fields,
chroma blending in interlaced PAL DVD
and YV12)

:confused::scared:

Fasola

[trbarry]

Fasola_Jan -

I don't know what the capture cards do but I heard recently (rumored?) that, while the NTSC standard hasn't officially changed, in practice what they are sending has shifted to be closer to PAL. But I don't remember where I heard that.

I recently wrote an Avisynth filter to handle a similar task, converting from BT.709 color (HDTV) to BT.601 (SDTV, NTSC). They too are just slightly different. If you were going to tackle this you might want to take a look at that one first. See:

www.trbarry.com/BT709ToBT601.zip (source & dll)

- Tom

[Fasola_Jan]

Hi :)

The funny thing is, that according to Sigma Designs site
chromaticities for HDTV, PAL and Secam
(CIE illuminate D65) are the same.

NOW I am confused.

Fasola

[trbarry]

I didn't know that. ;)

I guess I'm confused too. The differences aren't really much anyway but they can be seen. Here's a sample of running my filter against an HDTV clip:

www.trbarry.com/BT709ToBT601.2.jpg

- Tom