Re: [matplotlib-devel] PS, dpi, and imshow

[Darren D. <dd...@co...>]

I don't know how (or if) this can be improved, but I will gladly consider 
patches.


On Thursday 31 August 2006 03:09, Michael Fitzgerald wrote:
> Hi all,
>
> I have a question about the PS backend (building on the thread
> "imshow with PS backend" from ~ a month ago).  Evidently this backend
> is fixed at 72 dpi.  This isn't a problem with vector information.
> However, it would seem that one would want to use a higher resolution
> when plotting figures that use imshow() for raster data, since this
> command has several choices for interpolation.  As I understand, the
> AxesImage is sampled at this low-resolution when being written to PS/
> EPS.  Subsequent interpolation is done when printing, or viewing with
> ghostview.  For the (originally?) raster data, gv seems to use a
> nearest-neighbor scheme, making the image blocky.  It would be nice
> to use matplotlib's interpolation instead.  Is there a fundamental
> reason this needs to be fixed at 72 dpi?  As some publishers ask for
> EPS files of e.g. 300 dpi, I would think it's theoretically possible
> to export at different resolutions.  My understanding is that the
> _preview_ image in the file is supposed to be 72 dpi.
>
> One possible workaround is to scale up the size of the figure (in
> inches), but then fonts, line thickness, marker sizes, etc. must also
> be scaled, making it less-than-satisfactory.
>
> Thank you in advance for any enlightenment, and please forgive my
> ignorance -- I must admit I don't know that much about PS, nor about
> the specific scheme used in matplotlib for getting the image data
> into the postscript file, so I may be critically mistaken in the
> above assessment.