"Jason is desperate to play in the Premier League, and is very hungry," Martinez told the Wigan Observer. "His ability will shine through because he is a natural goalscorer.
"Every manager wants a player who has that clinical ability to make something happen in the penalty box - and Jason is a key signing.
"He is as strong on his left foot as he is on his right."
Martinez, who snapped Scotland up in a £2m deal from Swansea, added: "Strikers like Jason are difficult types to find in world football, but he is extremely capable.
"He has got an uncanny knack of scoring a goal out of nothing and he will give us a completely different option to work with.
"He holds the ball up well, is a fine finisher and has a magic touch.
"I have every faith he can make the step up to the Premier League and become a cult hero at Wigan.
"I know from experience how the Wigan fans love a goalscorer. Graeme Jones, Andy Liddell, Nathan Ellington, Jason Roberts.
"I am confident Jason can be the next name on the list."