Correct spelling, explanation: picture is the correct form because the word comes from Latin pictura (painting). As you can see there is also a t consonant in the original, and it remained in the English version. This points to picture as the correct form, which makes picure incorrect.

Definition of picture:
noun, a visual representation of something, painted, drawn, or photographed
That’s a very nice picture! Who is the author?
verb, a process or art of painting or drawing; to imagine sb or sth in a particular way
Can you picture Sheryl in this dress? I think she would look lovely!

Incorrect spelling, explanation: this form is incorrect, as t is required in the word: picture. This shows both in origins (Latin pictura) as well as pronunciation (although it may be almost silent for some listeners). Therefore picure is incorrect and the correct form is picture.