Change ConvertToRGB to consider display primaries

yesgrey · 1st July 2007, 22:40

Hi,

I have a suggestion to this filter that would be great. Unfortunately, I don't have the skills to implement it myself. Maybe someone here could do it, it appears to be a simple thing.

I know this filter already considers the 601 and 709 colorspaces. But there is still a problem: the correct primaries of the display.

We can convert a video to RGB that was created with ITU.BT-709 colorspace, but the colors only will show correctly on screen if the display primaries are the ITU.BT-709 ones. The problem is there are several displays with different primaries, and when we display the video on it the colors are not correct.

I have done some math and realized that if we correct for the display primaries we could have the correct colors on screen. Since this correction is just a multiplication of the YUY2->RGB matrix and the correction matrix, this could be easily done in ConvertToRGB.

My idea is:
The user specifies the primaries color coordinates(red,green,blue and white point) and with this we can calculate the matrix for the correction. Multiply the correction matrix with the YUY2->RGB matrix. Convert YUY2 to RGB.

The primaries color coordinates could be obtained with a colorimeter.

The ideal solution is correcting the primaries in the display, but only some displays have this capability.

I could post my test files with the calculations I have performed if someone would like to look at it.

Thanks.

1st July 2007, 22:40	#1 \| Link
yesgrey Registered User Join Date: Sep 2004 Posts: 1,295	Change ConvertToRGB to consider display primaries Hi, I have a suggestion to this filter that would be great. Unfortunately, I don't have the skills to implement it myself. Maybe someone here could do it, it appears to be a simple thing. I know this filter already considers the 601 and 709 colorspaces. But there is still a problem: the correct primaries of the display. We can convert a video to RGB that was created with ITU.BT-709 colorspace, but the colors only will show correctly on screen if the display primaries are the ITU.BT-709 ones. The problem is there are several displays with different primaries, and when we display the video on it the colors are not correct. I have done some math and realized that if we correct for the display primaries we could have the correct colors on screen. Since this correction is just a multiplication of the YUY2->RGB matrix and the correction matrix, this could be easily done in ConvertToRGB. My idea is: The user specifies the primaries color coordinates(red,green,blue and white point) and with this we can calculate the matrix for the correction. Multiply the correction matrix with the YUY2->RGB matrix. Convert YUY2 to RGB. The primaries color coordinates could be obtained with a colorimeter. The ideal solution is correcting the primaries in the display, but only some displays have this capability. I could post my test files with the calculations I have performed if someone would like to look at it. Thanks.