Film-Tech Forum ARCHIVE: Color Space Conversion YUV/RGB to XYZ

This is topic Color Space Conversion YUV/RGB to XYZ in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Jordi Aguila (Member # 9875) on 03-23-2017, 11:33 AM:

Hi to all,

normally the mastering DCP softwares have the option to change the color space from YUV/RGB to XYZ directly, but all the cinemas works in P3 and we have tested in our color grading room to change from DCP in XYZ to YUV/RGB directly (like the mastering softwares) and we see that we don't have the same color but, if we change first to P3 and then to YUV/RGB we see the same on the screen and in our monitor.

In resume: to do a correct color space conversion, we have seen that is necesary to 1st change to P3 and then apply the conversion to XYZ.

Anyone can confirm this color space conversion workflow?
And why the softwares don't do the correct way?

Thank you.

Posted by Bobby Henderson (Member # 840) on 03-23-2017, 12:24 PM:

I don't do color conversion work on video, but do it all the time with image graphics. I usually get better results by working in deeper color bit depths and doing the conversions in such a color space.

For instance I can go from RGB, CIE L*a*b and CMYK more effectively in 16-bit per channel depth and deal with gamma limit differences more easily, avoiding all kinds of strange noise and banding in the image. There's 65,000 levels from white to black in each channel rather than only 256 in 8-bit per channel color.

Posted by Carsten Kurz (Member # 5396) on 03-23-2017, 03:24 PM:

XYZ is the storage colorspace of the DCP. P3 is the transfer/display colorspace of projectors.

Sourcecolorspace -> XYZ->DCP->Server->P3->projector.

There is no error in converting common source colorspaces to XYZ directly (these conversions may be very different for different source colorspaces).

Without knowing what your hardware and software is setup and calibrated to, I have no idea what might be wrong.

- Carsten

Posted by Monte L Fullmer (Member # 2797) on 03-23-2017, 08:00 PM:

On our Barco units, we have created a macro preset with adjusted color space settings (PCF files) created for such external video sources via HDMI input.

This was all due to the color space being different from those outside sources than the actual default DCP color space.