2016.08.20 23:47 "Re: [Tiff] 32 bits per sample", by Bob Friesenhahn

On Sat, 20 Aug 2016, yufengs@andrew.cmu.edu wrote:

>

  And I also uploaded it (named
 'Yufeng.tiff') to ftp.graphicsmagick.org/incoming/graphicsmagick
 I'm
 sorry it's a little big, about 25MB.

Your floating point TIFF uses an unusual range. Unfortunately, it is usually necessary to read the TIFF data twice in order to know how to properly scale the data for viewing.

Through a bit of trial and error I found that the data ranges from 0.0 to 0.01. GraphicsMagick defaults to 0.0 to 1.0.

I am able to make sense of your data like

   gm convert -define tiff:min-sample-value=0.0 \
     -define tiff:max-sample-value=0.01 Yufeng.tiff Yufeng.jpg

Using

   gm convert -define tiff:min-sample-value=0.0 \
     -define tiff:max-sample-value=0.01 Yufeng.tiff \
     -gamma 2.2 Yufeng.jpg

helps when displaying the image on a computer.

Bob
--
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/