[Octave-bug-tracker] [bug #55907] png plot does nor respect dpi and produces unreadable results

[Rik]

Follow-up Comment #3, bug #55907 (project octave):

Are you saying that you don't get an error when you run the print command?


clear all
close all
sombrero
print -dpng ./MyPlot.png -S4000,3000 -r1000


If so, that is a different issue to debug.

The "-r" and "-S" options are for different things.  The "-r" option sets the
resolution (DPI).  It does not set the size of the figure.  If you want a
particular output size, use the paperXXX properties.  See Matlab documentation
(https://www.mathworks.com/help/matlab/ref/print.html) for which Octave has to
maintain compatibility.

The "-S" option is for setting the size of the output in pixels.  Normally,
the number of pixels would be determined automatically by Octave as  


number of pixels = physical_size (in inches) * DPI


But by using the "-S" option you have explicitly said how many pixels you want
and the resolution is irrelevant.  It's not an error to specify the two
options together, although maybe a warning would be useful that the "-S"
option takes precedence.

If this is unclear, you could suggest help text for the print command that
would better document it.


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