> The >235 Y' values aren't uncommon --- I've seen that referred to as > "Superwhite". These values don't map to anything in R'G'B', though, > and need to be clipped if working in R'G'B'. Otherwise, consider it > >Actually, my current denoise color-correction uses RGB, so I guess I'd >better be careful (or correct in YUV).
If you can stay in Y'CbCr, you are better off. Going back and forth between the two colorspaces is a lossy operation. > (Do you really get 0's and 255's in there? I thought that they were > actually illegal values in Y'CbCr, to be used to indicating sync stuff > or other out-of-band info. The actual legal range should be 1-254 for > all planes.) > >Yep - in one frame I have 41 0's and 59 255's. I believe you are >correct that they are illegal, but then yuvcorrect is my new best >friend... Hmmm... I wonder if those 0's and 255's are coming from the camera, or from a fencepost/corner error in libdv. >I assume that a properly calibrated TV won't show any difference >between Y=16 and Y=1, though? Not that I have any of those >(calibrated TV's, that is)... It shouldn't show any difference --- the electron gun can't get any darker than black. In fact, the right way to set the black level on your TV involves adjusting it until a black and a 'blacker-than-black' signal look the same. (Incidentally, the original reason for NTSC setup --- a 7.5 IRE difference between 'black' and 'blanking' levels --- was to make absolutely sure that the electron gun in the TV tube was turned off during horizontal retrace, even if the circuitry was a bit off. It made the whole viewing experience that much more robust at the time.) > PS: Thanks for discovering the +16 offset in smil2yuv; that would have > annoyed me to no end if I had found out after burning plastic... > >You're welcome. I somewhat recently got this camera and a DVD burner Plus, all this talk of clipping got me to look over my colorspace conversion code in mjpegtools again --- and I found a pair of bugs in the clipping. Yeap. Fix checked into CVS. -matt m. ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ Mjpeg-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/mjpeg-users
