john smith wrote:
I didn't know about .tif format being uncompressed.

TIFF is kind of like a standard "container" that can have various kinds
of image data in it. The more common kinds of data are not compressed,
though.

I am also being a little sloppy and saying "compressed" to mean "lossy
compression". Lossy compression is what JPEG images and MP3 audio files
do - they throw away the pieces that humans will have a hard time
perceiving in order to get a small file size. This is great for Web
sites or other situations where you don't have all the storage space
or network bandwidth in the world.

Lossless compression is what GIF and PNG images and ZIP archive files do.
They do some math tricks to make the file size smaller, but when you
uncompress the file, what comes out is always an exact bit-for-bit copy
of what went in. This is better for archival purposes; the compression
helps it take up less disk space, but somebody later can always get back
exactly what you scanned in or recorded.

Matt Roberds