radpanic 
"[@kleptomage":](/1938954#comment_7814045
)
On Twitter, right-click the image (while viewing the original post, not in the zoomed picture viewer) -> "open image in new tab" -> take the URL and stick ":orig" at the end.
It's a real crapshoot; sometimes that trick works, and sometimes it just doesn't. Sometimes it only works if you're on the mobile version of Twitter. Sometimes the full-size PNG is clearly just a JPEG that got saved again as a PNG. But this time, the trick worked.
Oh, it's the transparency. If you upload a PNG with any transparent pixels, Twitter *won't* convert it to JPG and will just resize it. Which apparently means the original PNG will still be available via the ":orig" trick.
never big enough
On Twitter, right-click the image (while viewing the original post, not in the zoomed picture viewer) -> "open image in new tab" -> take the URL and stick ":orig" at the end.
It's a real crapshoot; sometimes that trick works, and sometimes it just doesn't. Sometimes it only works if you're on the mobile version of Twitter. Sometimes the full-size PNG is clearly just a JPEG that got saved again as a PNG. But this time, the trick worked.
Oh, it's the transparency. If you upload a PNG with any transparent pixels, Twitter *won't* convert it to JPG and will just resize it. Which apparently means the original PNG will still be available via the ":orig" trick.