2011.06.24 20:40 "[Tiff] 16-bit image", by Leandro Bugnon

2011.06.24 23:45 "Re: [Tiff] 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 /

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/