John Hunter wrote: > On Thu, Jul 24, 2008 at 10:00 PM, Ryan May <[EMAIL PROTECTED]> wrote: > >> What else is confusing is how that relates to DPI. When I change the >> figure's dpi, using set_dpi, (and redraw), I get physically *bigger* barbs. >> To me, if I'm actually specifying pixels, there's no way that they should >> get bigger when I change the DPI.
Ryan, I think you are giving the length in points (sort of, because of the bizarre size kwarg), not pixels. So you are right--the barbs are not 7 pixels long. The translation from points to pixels for the Agg backend depends on the dpi, as John says below. > > When you increase the dpi, the canvas gets bigger (inches*dpi equals > canvas size in pixels). If you are drawing in pixels, and not > scaling, the barbs should look smaller, since they are a smaller > proportion of the canvas size. So if this explanation is right, the > barbs will look smaller with larger dpi. > >> Then I also can't figure out what the PS backend is doing. If PS is >> hardcoded to 72 DPI, why does passing dpi=72 to savefig() have any effect? > > ps should be unaffected, but dpi dependent backends will. By setting > the dpi to be 72, it should make the *other* backend look like the ps > backend and the ps backend should be unaffected. I don't think so, unless I am misunderstanding your phrase "make the *other* backend look like the ps backend". If you pass 72 dpi to the Agg backend, you will get a relatively small number of pixels, and when you display it at natural size on the screen, it will be tiny--only a little more than half-size on my laptop screen, for example. Whereas, if the ps renderer knows the screen dpi, then it will display full-size. > > JDH ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
