Screen Size for Game Gear Emulator

(Sorry if posted on wrong section - I have searched but could not find anything anywhere)

Is there any way to change the screen size on the Game Gear Emulator for the PSP.

The 'original' Game Gear screen size is marked on the PSP screen but the image is smaller (very much smaller) than this and game play is rather difficult

Please can someone tell me if there is a way to change the screen size so that it reflects what the Game Gear really was

Thanks