Another change over time is that the native Photoshop format appears to
have overtaken the LZW codec in terms of reducing many of the kinds of
files I've seen saved in both formats. It may in fact include a similar bit
of math, methinks.
FYI What I recall is that LZW is a form a bit mapping, where the unique
colors of a file are noted only once. There is then a set of instructions
that say which other pixels will contain that color. Complex images using a
limited palette will benefit most from this technique. No artifacts are
>No, LZW isn't lossy like JPEG and won't introduce any artifacts. Years ago,
>most print professionals recommended against using LZW with TIFF's if you
>were going to place the files into a page layout program (like Quark,
>Pagemaker, etc.). Apparently the software couldn't extract the compressed
>data. But I believe this problem has long since been fixed and most
>printers now recommend it to save space.