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#1149 png file of heat plot made with Octave: falsified colormap

closed
nobody
2D plot (258)
5
2012-08-05
2012-07-06
No

This error can be reproduced executing the attached Octave script.
The script configures a self-defined colormap, Then a so-called heat diagram is plotted on the computer screen, which shows four different color bars. Afterwards this diagram is saved (using indirectly gnuplot) to the disk as a PNG image. Using gnuplot 4.4 patchlevel 4 two of the color bars are different for the diagram on the screen and the image file saved on the disk. With gnuplot 4.4 patchlevel 0 the color bars of the diagram on the screnn as well of the image file saved on the disk are equal, which is as it should be.

This error occurs with gnuplot 4.4 patchlevel 4 which comes with Ubuntu 12.04.
This error does not occur with gnuplot 4.4 patchlevel 0 which comes with Ubuntu 10.10.
GNU Octave, version 3.2.4 which comes with Ubuntu 12.04 and 10.10 was used to plot the diagram.

Discussion

  • Ethan Merritt
    Ethan Merritt
    2012-07-06

    Is there some way you can provide the actual gnuplot commands that are generated by Octave?

    It is basically impossible to debug a problem when the only information provided is that the output images from a 3rd-party program using two older versions of gnuplot are "different".

    Do I understand correctly that gnuplot displays the graph correctly on the screen, and it is only the conversion to PNG that is a problem? What happens if you ask for JPEG or PostScript output?

     
  • Ethan Merritt
    Ethan Merritt
    2012-08-05

    No response.

    Cannot debug without a test script and further information about terminal types.
    Anyhow, no further releases will be made in the 4.4 series so we need to know whether the problem exists in 4.6 also.

     
  • Ethan Merritt
    Ethan Merritt
    2012-08-05

    • status: open --> closed