Re: Jeri videoboard gfxconv

From: Hársfalvi, Levente (
Date: 2001-05-26 11:47:07


William Levak wrote:

> You have to be careful here not to adhere too strictly to the
> mathematical.  The human eye and brain does not interpret colors
> according to what is mathematically the best fit.  Yellows and flesh
> tones are interpreted by the eye as wrong when only slightly off.
> Most TV's distort the color a little to emphasize flesh tones at the
> expense of other colors.

Well, I'd be happy if this thing worked just on the pure mathematical basis
;-). Later it could be possible to enhance it (since, as I understand,
perception should be possible to model with some tricks where the program
calculates differences (errors) between the colors.

Regarding the TV color distortion: I haven't noticed this on PAL TVs (PAL
has another artifacts, especially at areas where Y has high freq
components). I can sometimes recognize TV programs that were recorded in
NTSC (American or Asian TV transmissions). The color difference is
noticeable, especially (as you ? said) in the green area (somehow, the
colors seem to be 'green'ish, and the picture misses 'highlights' (sky is
'darker' than on PAL records), but that may also be because of signal

This program works in pure RGB color space; HSB would be more close to the
human eye, but I'm not familiar with it, and as I said I'm currently rather
focusing on presenting a 'working' routine; RGB is simpler to deal with.
(But if someone knows how to deal with HSB, I'd be happy to know that).

Best regards,


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