2007.08.29 09:59 "Re: [Tiff] Bits/sample must be 1 for Group 3/4 encoding/decoding", by Gerben Vos

$ ppm2tiff -c g4 pag-160.ppm lixo.tif lixo.tif: Bits/sample must be 1 for Group 3/4 encoding/decoding.

$

You're forcing ppm2tiff to use G4 encoding, which can only be done with black-and-white images. Remove the "-c g4" from your command line.

Gerben Vos.