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June 2011
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2011.06.24 23:45 "Re: 16-bit image", by Bob Friesenhahn
On Fri, 24 Jun 2011, Leandro Bugnon wrote: > Thanks for the quick answer. Here is a test image > * http://www.filefactory.com/file/cc0b359/n/test1.tif > > Another thing that cannot understand is that TIFFTAG_SMINSAMPLEVALUE > / TIFFTAG_SMAXSAMPLEVALUE remains in zero > value but I changed that in the code. Yes, I see that they are zero. GraphicsMagick says that you have two image frames: Type: grayscale Depth: 15 bits-per-pixel component Channel Depths: Gray: 15 bits Channel Statistics: Gray: Minimum: 500.00 (0.0076) Maximum: 700.00 (0.0107) Mean: 583.11 (0.0089) Standard Deviation: 84.91 (0.0013) and Type: grayscale Depth: 14 bits-per-pixel component Channel Depths: Gray: 14 bits Channel Statistics: Gray: Minimum: 1000.00 (0.0153) Maximum: 1400.00 (0.0214) Mean: 1166.21 (0.0178) Standard Deviation: 169.82 (0.0026) From this it is clear that the images are very dark and would appear black on a typical 8-bit display. However, if I normalize the image your test pattern is revealed. You say that the CCD is 14 bits, but the numeric range is within 11 bits (2^11 = 2048). The values are clearly not scaled up. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/