Use pamstretch and pnmscale to scale by non-integer values
pamstretch-gen N [pnmfile]
pamstretch-gen is a program which uses pamstretch(1), pnmfile(1), and pnmscale(1) to smoothly scale up a PNM file by any ratio; it's like a more general version of pamstretch (hence the name). But other than the `any ratio' bit, it's much the same as pamstretch. :-)
Uses awk just to make some simple floating-point calculations, which is probably overkill. But using dc makes my head hurt.
Russell Marks ([email protected]).