iphone - Crop an image to make a process on the result -

i want recognise text written in image, want crop image make process on desired part not image. idea how can ? here code using on image:

nsstring*ret= [self doprocess:capturedimage]; 

here want crop captured image make process on it.

you can define cgrect part of image want extract , use below method:

cgrect croprect = ...; uiimage *cropped = [uiimage imagewithcgimage:cgimagecreatewithimageinrect([fullimage cgimage], croprect) scale:fullimage.scale orientation:fullimage.imageorientation];