It might help if you tell us what it is you are trying to accomplish.

If you want to edit a TIFF file in perl, then it might be easier to convert it to another format, make your changes, and then convert it back. This should be possible in a lossless way.

I would recommend you look at the PBM/PGM/PPM format as a simple image format that can be converted to and from pretty much any other image format. Check out the Image::PBMlib module and the NetPBM package which contains tiff conversion utilities including tifftopnm and pnmtotiff.