I played with something like this a while ago. Interestingly, I found that my gzip'd table html had a smaller file size than the source png, even after png crush. Though I suspect I was doing something wrong to get a result like that.
I'm confident that resolutions are identical. I am using colspan and rowspan to do two dimensional run-length encoding, which may account for the difference. Even so, it's a surprising result.
http://disruption.ca/code/png2html/