It's pretty easy, especially with larger tarantulas. Looking at the inside of the abdomen of the molt, locate the epigastric furrow and should there be nothing but the furrow (flat), it's probably a male. If there is anything at all looking like a little pink flap, a couple red pimple looking things, or really anything at all potruding from the molt between the first pair of book lungs then it's a female. Different species have different sperm receptacles (spermathecae) some are paired and look like little devil horns, some are as simple as a couple little red pimple looing dots spread out, some are like a little flap (OBT's have this type) and there are some others (and a couple T's don't even have spermathecae :? ). But anyway, hope that helped. Your pic is kind of blury so I'm not going to make any for sure guesses, but I'll say male. I see two little red dots but cannot tell if they are spermatheca or just dimples in the crunched up exo. See if your cam can focus a little better and we'll help you out much easier. I'm putting money on male though (females of this species have a triangular flap as adults, not a pair of bulbs anyway).