Petr Danecek wrote: > Hi, > I'd like to open a high-quality image (600dpi) in matplotlib, add some > plots and save it as a postscript file. > It seems that whatever I do, the input image gets scaled down > :-(
I'm sorry I don't know enough about MPL's handling of images to help, but... > Looking in the code of matplotlib, there is a constant of 72dpi > hardwired everywhere. For instance, backend_ps.py there is the line > self.figure.dpi.set(72) # ignore the dpi kwarg This may not be what it seems. The native coordinate system for PostScript is in points, which are 1/72 if an inch, so it's common to force that as a dpi. Postscript supports fractional (is it floating point or fixed -- I'm not sure) points, however, so you can define things in higher resolution, and I'm pretty sure you can imbed an arbitrary dpi image in a a PostScript file, using the 72dpi to positions the image. The problem comes if the code, in addition to using 72dpi, also assumes integer coordinates, then you can't get better accuracy that 72dpi, which is not very good, and is really bad if someone scales it up later. wxWidgets addresses this by hard-coding 720dpi, rather than 72, and dividing by ten when writing the postscript -- still a bit of kludge. I'm not sure what MPL does. -Chris -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception [EMAIL PROTECTED] ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
