I was not referring to correction but color change. We would sometimes intentionally make people look green in a commercial for a digestive aid or pull down chroma completely for a black-&-white picture. There was nothing non-standard about the resulting picture; the proc amp replaced the burst.
Fancy color manipulation is something else. It is, indeed, easier in component, but, even then, one might like to go to secondary and other colors. There were NTSC-based color-modification systems for those who wanted full grading controls.
TTFN, Mark On 12/15/2011 5:05 PM, Olivier Houot wrote:
Mark shubin wrote:Well, you need to change one (the burst or the subcarrier in the picture) relative to the other. It's a routine operation for processing amplifiers (proc amps).So you can achieve both phase and amplitude modification by touching the burst, as it is outside the modulated part of the video line (at the price of potential non compliance)? Or, for amplitude would you try a comb filter with adjustable gain ? But i think i used an incorrect word when i asked my question about color correction. To you it probably means : to compensate for any unintended drift in chroma that would have occurred during processing. But perhaps i should have said: color modification. In component you would have the capability to tweak the amount of red, green or blue primaries at will. But in the modulated signal you would have to adjust independently the luma (which mostly contains green but still has an amount of red and blue components) R-Y and B-Y, so you would have to compute a modification of those three that achieves the correct primaries ratio, despite their relationships, and apply them to each targetted part of the signal despite the fact they are all mixed together in the composite signal. It does not seem reasonable, so i suppose for this you do have to demodulate. Or would you say this kind of color modification is not needed very often in the profession anyway? ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.
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