If you have a shot of that background without the person there, you could motion track it into place. If not, you’ll have to recreate the background image in Photoshop and motion track that into place and then match the noise and grain.
Either way you may have to rotoscope, if the guitar goes in front of it. But, if you have CS5+, it won’t be very difficult. The Roto Brush tool should handle it well.
Alternatively, you could just crush the blacks a bit in your color grading and eliminate the issue completely.
– The Great Szalam
(The ‘Great’ stands for ‘Not So Great, in fact, Extremely Humble’)
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