bugGNU Octave - Bugs: bug #50825, colorbar shows reversed color...


bug #50825: colorbar shows reversed color scheme using gnuplot 4.x

Submitted by:  Alois Schlögl <schloegl>
Submitted on:  Tue Apr 18 11:46:03 2017  
Category: Plotting with gnuplotSeverity: 3 - Normal
Priority: 3 - LowItem Group: Regression
Status: ConfirmedAssigned to: None
Originator Name: Open/Closed: Open
Release: 4.2.1Operating System: GNU/Linux

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Tue Apr 18 16:59:04 2017, comment #3:

I can confirm the same with gnuplot 4.6.

There were many improvements made to support gnuplot 5 in Octave 4.2, and also some effort made to ensure that those changes didn't break anything essential with gnuplot 4.6. I'm sure a patch would be welcome to solve this as long as it doesn't also break the correct behavior with gnuplot 5.

Mike Miller <mtmiller>
Project Administrator
Tue Apr 18 16:49:00 2017, comment #2:

I can confirm when using gnuplot 5.0.6, the problem is gone.
In my earlier test I've been using gnuplot 4.6.6 from debian/jessie.

The release notes of Octave 4.2 [1] say :

    • gnuplot 4.4 is now the minimum version supported by Octave.

but there is no indication that gnuplot 4.6 must not be used.

With earlier version of octave (e.g. 4.0.0, 3.8), gnuplot 4.6 was working fine. Checking the config.log from octave 4.2.0 and 4.2.1 do not provide any hint that gnuplot 4.6 would not be supported.

[1] https://www.gnu.org/software/octave/NEWS-4.2.html

Alois Schlögl <schloegl>
Tue Apr 18 12:57:50 2017, comment #1:

I cannot reproduce with gnuplot 5.0.5 (attached) (octave 4.2.1).


(file #40437)

Dmitri A. Sergatskov <dasergatskov>
Tue Apr 18 11:46:03 2017, original submission:

When plotting the colorbar with gnuplot, the colorscheme is reversed. When using fltk, and qt, the colorscheme is fine (see attachedments. The following script was used to generate the figures.

for g = {'fltk','gnuplot','qt'}
close all
imagesc(x); colorbar

Alois Schlögl <schloegl>


(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach File(s):

Attached Files
file #40437:  5x5.gnuplot.png added by dasergatskov (12kB - image/png)
file #40433:  test_colorbar.m added by schloegl (173B - text/x-objcsrc)
file #40434:  5x5.fltk.png added by schloegl (14kB - image/png)
file #40435:  5x5.gnuplot.png added by schloegl (14kB - image/png)
file #40436:  5x5.qt.png added by schloegl (14kB - image/png)


Depends on the following items: None found

Items that depend on this one: None found


Carbon-Copy List
  • -unavailable- added by mtmiller (Posted a comment)
  • -unavailable- added by dasergatskov (Updated the item)
  • -unavailable- added by schloegl (Submitted the item)
  • -unavailable- added by schloegl

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    Follow 10 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Tue Apr 18 16:59:04 2017mtmillerPriority5 - Normal=>3 - Low
      Item GroupUnexpected Error=>Regression
      Summarycolorbar shows reversed color scheme=>colorbar shows reversed color scheme using gnuplot 4.x
    Tue Apr 18 12:57:50 2017dasergatskovAttached File-=>Added 5x5.gnuplot.png, #40437
    Tue Apr 18 11:46:03 2017schloeglAttached File-=>Added test_colorbar.m, #40433
      Attached File-=>Added 5x5.fltk.png, #40434
      Attached File-=>Added 5x5.gnuplot.png, #40435
      Attached File-=>Added 5x5.qt.png, #40436
      Carbon-Copy-=>Added -unavailable-

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