Can I post jail photos on the internet without breaking the law?

Under normal circumstances, yes. Mug shots are public record and therefore not necessarily restricted from sharing on the internet. Your specific facts might change this analysis.

As long as the person has been convicted of a crime (not just a misdemeanor) and your pupose for posting is legally legitimate, you should be able to post the shots. However, if you're intending to sanction or harrass or place the person in a false light or make racial or ethnic (or other protected class) derogatory remarks, don't post the shots. Frankly, this whole idea sounds a little creepy to me.