Hmm, I don't know, I'm going to take a stab in the dark and hope no one's face is there.
I used to have a similar problem but it was on IE, and I thought it was an IE specific issue. I went about it by specifying a really small font size, 1px or so, in the elements that were getting unnecessary padding. Even though there was no text in the div/table cell, something was stretching them, and it was fixed by simply doing that.
OK, I decided to test it, in the <table> with the dedimain images I put in a "style="font-size: 0px;" ", it decreased the gap to 1px high which is smaller than it was before, but no, it didn't completely eliminate it. What I'm saying is that it did do something so try playing with that.
Personally I'd simply try to avoid using tables, go with a div and display the images in a block, or something along those lines.
EDIT: Ok, I tried the div with "display: block;" thing... still doesn't remove the gap completely.. scratching my head right now...