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May 2005
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2005.05.30 09:42 "Re: Jpeg and YCbCr", by Jean-yves Le Ridant
> Apart from including ICC profiles, our best option to communicate grayscale in a > scientifically unambigious way, Have someone seen a ICC profile, a EXIF object, a BROUZOUF object, make something else than adding ambiguity ? ( Don't say waste CPU cycles and RAID cylinders, I know ) :-))) > is probably by using the L* component of L*a*b*. > If we were to say that Photometric=YCbCr and SamplesPerPixel=1 is not legit... I > don't think we have a legit way to store L* rasters, either. > > That may be a to pragmatic argument to be convincing, but I would like to add to > that, again, that Photometric=YCbCr and SamplesPerPixel=1, or > Photometric=whateverLab and SamplesPerPixel=1 is really unambigious. I would > hesitate to write it, for now, unless people here clearly indicate they feel the > same about this as I do, but I would certainly think you'll need to be prepared > to at least read it. Understand, that for this ... scope of image description, I have more questions than answers. I have not asked cause, at this point, and for some days, I'm involded under this level, with "raw" process of tifftif, to that tiff's part of colorspace/pixeldepth/signed-unsigned managemenent can be handled the same than for "line" process. A point is that, for example, CIELAB ( photometric 8), might ama be handled in some way similar to JPEGCOLORRGB .... What you say is quite some level more, cause it may involve all COMPRESSSION_xxxx, not only jpeg. -- Jean-Yves