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January 2007
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2007.01.17 08:07 "Re: Elevation Data", by Joris Van Damme
Bob, Bob Friesenhahn wrote: > Libtiff uses the names PHOTOMETRIC_MINISWHITE and > PHOTOMETRIC_MINISBLACK. This implies something different than > BlackIsZero. Does that help? It's confusing. I usually use the names MinIsBlack and MinIsWhite... What's in a name? > It seems difficult to make a completely interoperable image using > floating-point samples. I have heard that some software which > supports floating-point TIFF checks all the sample values in order to > best understand how it should be displayed (assuming it can be > reasonably displayed at all). In practice, you are correct. There's just not much floating point image data written, and the few that do write it aren't always concerned with interchange. But I do believe there is a consensus emerging, in that the description in my previous message does apply to the biggest part of what is 'out there', and the others have all kinds of ranges and as such don't qualify to derive a consensus from. > Adobe issued a new draft specification (dated April 8, 2005) which > discusses floating point in TIFF as implemented in Adobe Photoshop > CS2. Unfortunately, it does not address sample ranges other than to > reference openexr documentation. Correct. Best regards, Joris Van Damme info@awaresystems.be http://www.awaresystems.be/ Download your free TIFF tag viewer for windows here: http://www.awaresystems.be/imaging/tiff/astifftagviewer.html