On Wednesday 23 May 2007 00:11, Edouard Chalaron wrote: > Hi there > Just a newbie question. > The frames in XGA (1024x768) I need to process are in 8 bits 422 > uncompressed with logarithmic sampling.
I admit that I do not know what logarithmic sampling is. Does it mean that the pixels values are the logarithms of the "normal" linear pixel values? > So in order to get a linear scale I do apply the gamma correction. > However for the same gamma correction values the same footage in PAL > size give me a very different result, e.g. PAL looks ok and XGA looks > way too clear... > > My question is : Does frames size matter when it comes to the gamma > correction ? That may be the case because it depends how you transformed the 1024x768 to 720x576. Note that in a straight-forwardly scaled down version the pixels of the PAL frame are weighted means of the pixels of the XGA frame. This won't work if your pixel values are logarithms: If logarithms are added, the result is garbage, not logarithms. Therefore, I think that the PAL frames that "look ok" are actually incorrect. -- Hannes _______________________________________________ Cinelerra mailing list [email protected] https://init.linpro.no/mailman/skolelinux.no/listinfo/cinelerra
