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January 2007
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2007.01.17 16:08 "Re: Elevation Data", by Bob Friesenhahn
On Wed, 17 Jan 2007, Joris wrote: > > It makes sense for floating point grayscale data, or any data under that > Photometric tag, to assume the range of 0.0 to 1.0, simply because there > is no other intrinsic range on this. For example, 0.0 to 255.0, makes no > sense, unless there is something intrinsic in the concept of grayscale > that binds it to 8 bit ranges in particular. Amongst the few testfiles I It seems that the 0.0 to 1.0 range is "popular". A 0 to 100 range seems just as useful. Other ranges may make better use of the floating point values and avoid unnecessary quantization. When original values are obtained from physical sensors (natural integer producers) and stored as floating point, it may make sense to use a floating point range which matches the sensor's range since doing so avoids any possiblity of quantization error due to storage. Bob ====================================== Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/