How do I determine if the raw is JPG or PNG if the 1280 link was JPG?

Edit: I tried a raw.png on a JPG and got "AccessDeniedAccess Denied". So I haven't fucked up just yet.

Edit 2: Check out how the pixellated speckling pops out on this one.

http://68.media.tumblr.com/8ce3f760a5c8259b29eb4fb4787fc4d9/tumblr_inline_oc0zn5zAfV1qlqtgz_1280.jpg
http://68.media.tumblr.com/8ce3f760a5c8259b29eb4fb4787fc4d9/tumblr_inline_oc0zn5zAfV1qlqtgz_raw.jpg

Also, it appears that raw images can be found even if the Tumblr post that had them was deleted. As long as you have the direct image link.

Edit 3: Slight blurriness melts away from 1.6% increase in dimensions:

http://68.media.tumblr.com/3b0511edc585227d3ac0f6584180d090/tumblr_oej3g5s6Df1rod6vmo1_1280.png
http://68.media.tumblr.com/3b0511edc585227d3ac0f6584180d090/tumblr_oej3g5s6Df1rod6vmo1_raw.png