[Octave-bug-tracker] [bug #41674] Temporary arrays in imresize are doubles

[Ian Journeaux]

URL:
  <http://savannah.gnu.org/bugs/?41674>

                 Summary: Temporary arrays in imresize are doubles
                 Project: GNU Octave
            Submitted by: ijourneaux
            Submitted on: Sat 22 Feb 2014 11:30:23 PM GMT
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Performance
                  Status: None
             Assigned to: None
         Originator Name: Ian Journeaux
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.8.0
        Operating System: Microsoft Windows

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Details:

When using imresize on larger images, I end up running out of memory. In the
process of troubleshooting this, I noticed that in 
imresize there is a call to meshgrid
 
[XI, YI] = meshgrid (linspace (1, inCols, outCols), linspace (1, inRows,
outRows));

im = imremap (im, XI, YI, method);

Since the default cast for XI and YI is double, the memory footprint is very
large for large images.

If the arrays XI and YI are cast as single the out of memory condition is
avoided. 

This is probably not the ideal solution (or even a good solution) but it
dramatically reduces the memory footprint of imresize.

Ian




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