Re: Invert colors with ghostscript

[Jeffrey H. Coffield]

Nuno J. Silva wrote:
> I've been doing research on how to invert the colors of a document which
> is being viewed with gv (or any other ghostscript-based viewer). 
>
> ATM, the only thing I found is a small trick which works with some
> files, not all (adding the command "{1 exch sub} settransfer" at the
> beginning  of the file), but this does not work with every file, and as
> postscript and pdf documents are formats to be used with printers, not
> screens, all of them are generated using white background and black
> foreground (that being the right color set for printing), it would be,
> IMHO, cleaner if this sort of "magic" was made by gv, or better, by
> ghostscript.
>
> So, I wonder if there's any ghostscript options to invert colors (white
> is changed for black (and vice-versa), images are turned into negatives,
> etc.).

Perhaps you need to also use setcolortransfer and redefine showpage to 
be something like this:

/showpage {showpage 0 0 pagewidth pageheight rectfill} bind def

to turn the background from white to black

Jeff C.