Home Theater Forum - View Single Post - Does HD playback affect Display color space needs?

Allan Jayne · 06-10-2006, 10:59 AM

I would expect that for projection technology absolutely correct gamut can be achieved because a correct colored cellophane can be placed over the CRT or in a DLP color wheel. Whereas for direct view, the color is less accurate because getting the correct amount of color dye into each tiny pixel position is critical, or alternatively we have to rely on the color we can get from available phosphors.

For many years the red phosphor on CRT's was a little on the orangish side immediately resulting in a gamut that fell short in the red region.

Next we will need test patterns and a myriad of controls (similar to 100 point convergence*) to adjust the color video signal so it tracks the gamut properly.

* For example a horseshoe shaped CIE diagram with little colored circles superimposed on it and the person doing the calibration is supposed to make the color in each circle match the surrounding color.

Repeat, going back and forth iteratively, looking through red, green, and blue cellophanes that came with your AVIA DVD to make sure the little circles as seen still match the background they are over.

And the TV will need separate memories for HDTV versus analog broadcasts in order to save the laboriously done calibrations.

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06-10-2006, 10:59 AM	#5 of 5
Allan Jayne Member Join Date: Nov 1998 Local Time: 02:48 AM Local Date: 12-03-2008 Posts: 3,596	Re: Does HD playback affect Display color space needs? I would expect that for projection technology absolutely correct gamut can be achieved because a correct colored cellophane can be placed over the CRT or in a DLP color wheel. Whereas for direct view, the color is less accurate because getting the correct amount of color dye into each tiny pixel position is critical, or alternatively we have to rely on the color we can get from available phosphors. For many years the red phosphor on CRT's was a little on the orangish side immediately resulting in a gamut that fell short in the red region. Next we will need test patterns and a myriad of controls (similar to 100 point convergence) to adjust the color video signal so it tracks the gamut properly. For example a horseshoe shaped CIE diagram with little colored circles superimposed on it and the person doing the calibration is supposed to make the color in each circle match the surrounding color. Repeat, going back and forth iteratively, looking through red, green, and blue cellophanes that came with your AVIA DVD to make sure the little circles as seen still match the background they are over. And the TV will need separate memories for HDTV versus analog broadcasts in order to save the laboriously done calibrations. Last edited by Allan Jayne : 06-10-2006 at 11:08 AM.