yuv levels in fcp?

M

mattsand

Veteran
hi,

do you know how the 0-255 levels the d90 produces (verified using jpeg snoop) are mapped to the 16-235 video levels in fcp? it looks as if the black level is mapped correctly to 16, i don't see any clipping, but the highlights are harder to judge visually and while i see in the scopes that they max out at 235, i.e. no superwhites, i've no idea whether they're clipped in camera or in fcp/quicktime. anyone knows, or can tell me how to figure it out? thanks.

/matt
 
yes, but the camera clips too so it's hard to say where it happened. i need to shoot something that's just barely clipped i guess, but how is that possible without zebras?

/matt
 
Maybe shoot a basketball covered with a white sheet in full sunlight. At least PART of that image should be clipped.
 
Thanks, i know how to blow it out but how do i know what's blown out? :-) This is not just an fcp issue btw, how do you guys check it in ae for example? I've found that if i use the picvideo codec on the pc i have to check the "assume normalized" to avoid clipping, but i'm still not sure if i'm avoiding it altogether, especially when using the quicktime opendml codec which doesn't have any options. /matt
 
JPEGsnoop can show a histogram. That may help you to find a frame which got information above 235 but not clipped at 255.

The histogram doesn't have a a scale though so it may be hard to use. Frames can be exported from the AVI as JPEGs. I'm not very familiar with Photoshop but i assume you can get a YUV histogram.

By the way, JPEGs use YCrCb. Is that luminance the same as luminance in YUV?
 
thanks, i'll try that. yuv is the new name for ycrcb if i understand it correctly. either way it's the same thing.

/matt
 
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