I put together this little utility for converting a color EPS/PDF/SVG to grayscale. http://www.tlhiv.org/grayscale/ Selecting "invert" swaps colors from white to black and black to white. So, using a black/white graphic on a transparent background should transform it to a white/black graphic on a transparent background. Testing is certainly necessary. Troy

For those that care, here is basically how the service works. The filter is applied to an SVG, and the uploaded graphic is converted to SVG using the following process: EPS -> PDF -> SVG PDF -> SVG SVG -> PDF -> SVG where the EPS -> PDF conversion is done with the standard `epstopdf` included with TeX. The PDF -> SVG conversion is done with `pdf2svg` which is available from http://www.cityinthesky.co.uk/opensource/pdf2svg and which uses Cairo and Poppler for its conversion. Now in order for my simplistic filter to function, all SVG's must essentially "look alike" (i.e., come from the same source). Therefore, uploaded SVG's are converted to PDF (using Inkscape) and then back to SVG (using `pdf2svg`). The filter then works with the resulting SVG and converts it back to the uploaded format using Inkscape. Troy

On Sep 15, 2012, at 1:36 AM, luigi scarso mailto:luigi.scarso@gmail.com> wrote: On Sat, Sep 15, 2012 at 1:23 AM, Troy Henderson mailto:thenders@gmail.com> wrote: and which uses Cairo and Poppler for its conversion. Now in order for my simplistic filter to function, Why 'simplistic' and not 'simple' ? I always thought that its meaning is negative (something like " 'simplistic' is a bad imitation of 'simple' ") That's often true. Here I think the intention is to imply that the filter is simple and naive, perhaps not robust, might not work for everybody, etc. In that sense, the meaning does have a negative connotation. ________________________________ This e-mail message (including any attachments) is for the sole use of the intended recipient(s) and may contain confidential and privileged information. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this message (including any attachments) is strictly prohibited. If you have received this message in error, please contact the sender by reply e-mail message and destroy all copies of the original message (including attachments).

2012/9/15 Troy Henderson :

Utilities are available in abundance which can transform raster graphics from color to grayscale, but until I created this yesterday, I have never seen a utility that keeps the graphic in vector format (i.e., never rasterizes it throughout the conversion) and converts it from color to grayscale. Until I read this thread, I guess I thought I was the only one that desired such a tool. I'm glad to see that at least I'm not alone.

Oh, there are, but I know only commercial (e.g. OneVision Asura) or in-house solutions (like what I "managed" at a newspaper several years ago). The simple (or simplistic) rgbcolor patch doesn't work with complicated EPS, of course. But then you'd need to know the structure of your EPS. It's hard to get that right for arbitrary EPS. And there aren't that many able PostScript programmers left. E.g. at that newspaper we were able to switch spot colors just before plate exposition; the trick was to use a generic spot color name throughout the workflow and to change its definition in the completed page EPS. (At that time "our" printing press was too small to print all pages in full color.) Since PostScript is a full programming language, most PS generators use shortcuts (macros/functions) that wrap the originally simple commands, so you often can't track down where the structure hides that you'd like to change. Best solution is often to do a full "expansion" with a PS interpreter and write a new, better readable, but mostly much bigger code. pstoedit is your friend for that – e.g. Hans did some nice tricks with EPS pictures converted to MetaPost. I once experimented a bit with changing colors of embedded bitmap images – it's rather easy to do, but never looks right without a deep understanding of color management and its strange implementation in PostScript... Greetlings, Hraban