Digital Light & Color

I have 48 bit TIFF files. When they are save uncompressed, the file size is roughly consistent with their pixel size (i.e. ~total pixels*3*2). If they are saved with ZIP compression, the files become slightly smaller (10-20% - the images have lots of details and noise). Some programs (e.g. FastStone can't read ZIP-compressed Tiffs). But when they are compressed with LZH compression, the files become larger than uncompressed! What's at play here?

It can be proven mathematically that there is no compression scheme that will not enlarge some files. Both LZW and ZIP depend on finding repeating patterns within the image which may be few and far between for noisy images. They compress the most on very soft images or images with large blocks of solid color.

I come across this problem often at work, although it's in binary computer data, not images. Problem's the same. Some algorithms work better with binary than others (generalising). Best is to turn it off if there's not a significant decrease in size, saves the compression/decompression algorithm overhead.