Screen grab color data

[Mark Wilkinson]

Does anyone know what color data is captured when a screen grab is taken? e.g. if one were to do a screen grab of a 4:2:2 QT image, would all that color data be intact?

 

[Mark Wilkinson]

bumb

 

[Michael Romano]

In OSX the operating system functions at 8bit so I think it might end up being downsampled from any higher bit depth. What I don't know is whether or not the 8Bit occurs coming out the video card or on screen render. Your color data *should* be intact excepting for that process. I think that might be better than exporting a still image from QT because I've seen gamma shifts going to PNG or other image formats direct and they are quite obvious.

 

[Mark Wilkinson]

Yes, the gamma shift is maddening - happens in screen grab as well as exports. A screen grab of HDV opened in Photoshop looks completely different from same grab in FCP. 8-bit was my guess as well, but just a guess.

 

[Michael Romano]

Humm... I don't get a gamma issue through screen grabs. Just tested it with both "Capture Selection" & "Capture Window" on a ProRes 4444 1080p .MOV file. Are you using 10.6.x or 10.5.x?

 

[Mark Wilkinson]

10.5.8 - pct out of HDV ftg

 

[Michael Romano]

Might have something to do with the OS. I've read that SL is supposed to have a video gamma space now so it might be respecting gamma through a screen grab. I don't have a 10.5 box to test this on though.

 

[Mark Wilkinson]

Thanks for the feedback -

 

[Michael Romano]

No worries! Do post if you come up with any kind of answer, I'm interested in best practices for grabs as well.