what the?

okay i was looking around deviantart to look at other people's works
saw some very amazing artworks
and then,
i happen to spot a drawing that looked awfully familiar...
haha it happens to be the katy perry drawing i did some time back
he photoshopped in some details and tilted the photo..
plus he erased my signature...
original drawing

copied work

sigh
okay i do feel kinda honoured that someone "stole" my artwork
BUT erasing my signature then calling it his own art
is just...
what the?