Re: Matching profile of image with a QuickTime movie frame?
Re: Matching profile of image with a QuickTime movie frame?
- Subject: Re: Matching profile of image with a QuickTime movie frame?
- From: Steve Upton <email@hidden>
- Date: Thu, 31 Dec 2009 17:44:08 -0800
At 9:31 AM -0800 12/24/09, Dan Wood wrote:
>I'm trying to grab a frame from a QuickTime movie (.mov, with H.264 track) and turn it into a PNG image.
>
>I've done this by opening the movie in Quicktime Player 7 (since the new Leopard QuickTime player doesn't do this), choosing "Copy", then going to Preview and choosing "New from Clipboard".
>
>Technically this works, but as you can see from the screenshot below, the Preview image (which you can see from the inspector is using a Generic RGB profile) clearly does not match the QuickTime movie in the other window.
>
>http://dl.dropbox.com/u/1284131/qt_vs_preview.png
>
>Any ideas how to even *find* what the profile of the QuickTime movie is, so I can apply it to the image? Or better yet, is there another technique for copying a single frame of a QuickTime movie and saving it -- with the correct profile -- to an image file?
I think there are a couple of things working against you.
QuickTime doesn't use a *profile* to display the movie on screen (as far as I know) but it *might* be assuming something about screen gamma. Up until Snow Leopard the "standard" gamma of a Mac was assumed to be 1.8.
There are certain applications / technologies that use that assumption (DVD Player for one, perhaps QuickTime Player) and the assumption cannot be changed. It has nothing to do with the calibration of your screen or what the current monitor profile is stating the actual display gamma is set to.
So, without reviewing your situation in detail, if your display is calibrated to gamma 2.2 then you might be fighting something in the Quicktime display path. If QuickTime assumes that video is in gamma 2.2 and alters it to be displayed on a gamma 1.8 screen then screen shots with the monitor profile assigned might appear different than frame copies with the monitor profile assigned.... make sense?
You could try a few things as tests:
- calibrate your display to gamma 1.8 (even if just temporarily) and then see if the color difference problem goes away.
- upgrade to Snow Leopard (obviously not the simple test). Snow Leopard reportedly uses gamma 2.2 as the system gamma and so DVD and QuickTime playback on a 2.2-calibrated display should look better (correct).
I'm interested to hear of any results you might have to offer...
regards (and Happy New Year)
Steve
________________________________________________________________________
o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o ColorGear ColorThink ColorValet ColorSmarts ProfileCentral
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