[Octave-bug-tracker] [bug #39249] imread and 32 bit (float) TIFF images

[Carnë Draug]

URL:
  <http://savannah.gnu.org/bugs/?39249>

                 Summary: imread and 32 bit (float) TIFF images
                 Project: GNU Octave
            Submitted by: carandraug
            Submitted on: Thu 13 Jun 2013 09:11:00 PM GMT
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

Octave does seem to deal well with 32 bit images. The two attached images
don't load correctly. "32bit-logical.tif" is a black square with white lines
and "32bit-gray.tif" is a black square with gray lines of different
intensities.

The "logical" image is read as binary image in Octave, when graphicsmagick is
built with quantum 32 or 16 (quantum of 8 not tested). I believe this may be
because GraphicsMagick only "see" 2 values.

Interestingly the "gray" image is read as 16bit in Octave if graphicsmagick is
built with quantum depth 16 (issuing the typical warning about being limited
by graphicsmagick quantum depth) but gives an error "imread: invalid image
file:  _magick_read__: image depths greater than 16-bit are not supported"
when graphicsmagick is built with quantum depth 32 (the one that should be
able to read it).

In matlab both images are read as "single".

The first problem may go deeper and come from some problems with
GraphicsMagick. I think the second is some hard coded limitation on our code
but I'll need to look into this.



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File Attachments:


-------------------------------------------------------
Date: Thu 13 Jun 2013 09:11:00 PM GMT  Name: 32bit-binary.tif  Size: 625kB  
By: carandraug

<http://savannah.gnu.org/bugs/download.php?file_id=28310>
-------------------------------------------------------
Date: Thu 13 Jun 2013 09:11:00 PM GMT  Name: 32bit-gray.tif  Size: 625kB   By:
carandraug

<http://savannah.gnu.org/bugs/download.php?file_id=28311>

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