Question

which free-to-use website is the best to get accurate and good quality scientific images? Preferably about biology.

Answer 1

http://www.sciencephoto.com/ is ok, though I'm not sure how "free" the images are (they're free to look at, but they may be copyrighted.)

If you want electron micrographs of ciliates, Richard Allen's site is fantastic: http://www5.pbrc.hawaii.edu/allen/ It's all quite specialised, but the images are good quality and they're often labelled and explained. You might find it interesting to just look at them and just marvel at the complexity of "simple" cells.

There are some other good sites too, but it might take me a little while to find them.

Answer 2

Here we go, this was the site I found recently: http://cellimagelibrary.org/ Lots of good images in there.

Answer 3

If you have less good biologic images and want to clean them up and process (i.e., get quantitative data from them), I suggest ImageJ.