[Octave-bug-tracker] [bug #55632] display of image pixels and axis limits

[Rik]

URL:
  <https://savannah.gnu.org/bugs/?55632>

                 Summary: display of image pixels and axis limits
                 Project: GNU Octave
            Submitted by: rik5
            Submitted on: Sat 02 Feb 2019 06:48:26 PM PST
                Category: Plotting with OpenGL
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

Octave "pixels" extend +/- 0.5 a grid point of their position.  This leads to
oddities, where part of a pixel would be outside the axes and is clipped. 
Matlab does not do this.

Sample code below is taken from the demo for brighten().


clf;
colormap (gray (64));
image (1:64, linspace (0, 1, 64), repmat ((1:64)', 1, 64));
axis ([1, 64, 0, 1], "xy");


This leaves a small white border around the image object which is not present
when using gnuplot or Matlab.

This may be a deep issue that needs to be resolved in the OpenGL renderer.




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File Attachments:


-------------------------------------------------------
Date: Sat 02 Feb 2019 06:48:26 PM PST  Name: image.png  Size: 12KiB   By: rik5

<http://savannah.gnu.org/bugs/download.php?file_id=46169>

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