You might try unchecking "Anti-alias text and line art" in the PDF panel in Preview's Preferences dialog to see if that helps.
Best regards, Scott On Oct 23, 2014, at 8:49 PM, Frédéric Vogt <frederic.v...@anu.edu.au> wrote: > Interesting development of the issue described below, shared with the list > for legacy purposes. > > As it turns out, which PDF viewer one uses does matter when it comes to > printing (on paper) matplotlib figures containing 'imshow' plots and saved as > .pdf. The problem I had was the result of printing the matplotlib figure via > Mac OSX's "Preview". If I print the same figure via Acrobat Reader, then the > grid in both panel look identical, the panel edges are sharp and crisp, etc > ... > > This most certainly points out towards a difference deep inside Preview and > Acrobat - haven't tried other PDF viewers. > > For reference, I am on Mac OS 10.6, used Preview 5.0.3 and Acrobat reader > 10.1.12. > > Cheers, > Fréd > > > On 23/10/2014, at 10:07 PM, Frédéric Vogt wrote: > >> Hi everyone, >> >> Using 'imshow' to plot a few arrays (arranged with gridspec) that I then >> export directly to a .pdf file using savefig, I noticed that when I print >> the .pdf file (i.e. on real paper) some of the subplots are blurry. >> >> To clarify: >> - in all my figures, there is always 1 subplot very sharp and crisp, and all >> the others are slightly blurry, >> - the effect is not visible on the screen at any zoom level, >> - the effect is very slight, and hardly noticeable ... until you plot a fine >> dotted grid - and then, it becomes evident (the grid points pop out a LOT >> more in the sharp plot), >> - the entire 'sub-image' is blurred (axes, on-image text, grids, etc...) but >> the axis labels and tick labels are fine. >> >> This effect is hard to describe, so I placed an example here: >> http://www.mso.anu.edu.au/~fvogt/mpl_tmp/ >> You can compare the original pdf (straight out of Python) and the >> 'scanned-printed' version. The scan is not of the highest quality, but you >> can definitely see that the grid on the left is fainter - and if you zoom >> in, the figure's edges are also less sharp. >> >> I tried (and failed) to find info on the web so far (I'm still searching). >> In the meantime, has anyone seen this effect before ? Is this a documented >> bug/feature ? >> >> I suspect that it may be related to how subplots (containing distinct >> images) are exported to .pdf, but it is a long way beyond my current >> knowledge of the savefig function. Note that playing with the dpi setting (I >> went up to 1200) doesn't help (I can see the improvement on the images >> themselves but the print blurriness remains). And just in case you wonder, >> the print bluriness also remains whether I print the .pdf straight out of >> Python or include it inside a Latex document first. >> >> Any ideas on how to fix/go around this ? >> >> Cheers, >> Fréd >> >> P.S.: The effect is not present if I export my figures in png. But for >> quality purposes, I'd much rather try to avoid going through png if I can ... >> >> ------------------------------------------------------------------------------ >> _______________________________________________ >> Matplotlib-users mailing list >> Matplotlib-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/matplotlib-users > > ------------------------------------------------------------------------------ > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users ------------------------------------------------------------------------------ _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
