[GRASSLIST:5102] Re: Postscript and png file comparison

[Glynn Clements]

Miha Staut wrote:

> As promised I am sending you an output of the same
> area in png and ps version. The used code was:

[snip]

> Please try comparing the two files and possibly print
> them too and see for yourself. The postscript file is
> displayes and printed with less resolution.

Yep. The raster in the PostScript file has half the horizontal
resolution: 296x565 compared to 592x565 for the PNG file.

It appears that ps.map tries to impose a hard-coded limit of 75dpi on
rasters (although the algorithm is rather dubious), halving the
resolution of the largest dimension in order to do so.

FWIW, the relevant code is in map_setup.c, preceded by the comment:

    	/* adjust sampling if too big */

-- 
Glynn Clements <glynn at gclements.plus.com>