🚀 go-pugleaf

In the referenced message, amanda@mermaid.intercon.com (Amanda Walker) wrote:
}What I would do is to do two imagemask commands.  The first paints the
}mask bitmap with white, and the second paints the image bitmap in black
}(or whatever).

Hmmmmmm....  This doesn't solve the precise problem I posed, since I
want to paint a grayscale image, but it's very close.  With a little
image hacking using my PBMPLUS toolkit I was able to make this trick
work quite well.  Thanks!

For the benefit of any other PBMPLUS/PostScript hackers out there
(and for my own future reference), here's what I did:

    pgmtopbm face.pgm > face.pbm
    {manually edit face.pbm to remove background, giving clipped.pbm}
    pbmmask clipped.pbm | pnminvert > mask.pbm
    pnmenlarge 5 face.pgm > face5.pgm
    pnmenlarge 5 mask.pbm > mask5.pbm
    ppmarith -mul face5.pgm mask5.pbm | ppmtopgm | pgmtopbm > clipped5.pbm
    pgmtops mask5.pbm > mask5.ps
    pgmtopbm clipped5.pbm > clipped5.ps

Then turn mask5.ps into an imagemask command with invert true and
0 setgray; turn clipped5.ps into an imagemask with invert true and
1 setgray; and adjust the translate and scale commands to shrink
the result back down by a factor of five.
---
Jef

  Jef Poskanzer  jef@well.sf.ca.us  {ucbvax, apple, hplabs}!well!jef
  A witty saying proves nothing, but saying something pointless gets
                          people's attention.