2005.05.25 09:52 "[Tiff] How to Write a tif file with compression = COMPRESSION_JPEG & photometric = PHOTOMETRIC_YCBCR ?", by Kelvin Zhong

2005.05.30 10:31 "Re: [Tiff] How to Write a tif file with compression=COMPRESSION_JPEG& photometric = PHOTOMETRIC_YCBCR ?", by Marti Maria


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 ) :-)))

ICC profiles, many times. Of course if you embed the wrong profile, then it is going to mess out your image, but used properly works quite well.

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.

YCbCr is a device space, Lab is a colorimetric space. You can use YCbCr based on Rec.601 or Rec. 709, to enumerate a few. But there is only one Lab. Well, you can argue Lab depends of white point, but this is another story.

Photometric=Lab and Samples per pixel=1 is legal as it is documented in the TIFF Technote #2 (March 22, 2002), see page 13:

SamplesPerPixel - ExtraSamples: 3 for L*a*b*, 1 implies L* only, for monochrome data.

Marti Maria.