1999.08.22 18:59 "RE: TIFF LZW : How select predictor", by Gilles Vollant

Tiff 6.0 doc say

<< LZW without differencing works well for 1-bit images, 4-bit grayscale images, and many palette-color images. But natural 24-bit color images and some 8-bit grayscale images do much better with differencing.>>

So Adobe Photoshop does like Adobe Tiff Spec