1. A method ( 300 ) of assigning pixel values to pixel locations in a region ( 110 ) comprising pixel locations of unassigned pixel values in an image ( 100 ), the method comprising: selecting ( 310 ) a first pixel location ( 120 ) in a first neighbourhood ( 130 ) adjoining the region of unassigned pixel values ( 110 ); selecting ( 320 ) a second neighbourhood ( 150 ) that includes the first pixel location ( 120 ); using a first set of pixel values of the second neighbourhood ( 150 ) to estimate ( 330 ) a direction ( 140 ) of an image feature ( 160 ) relative to the first pixel location ( 120 ); selecting ( 340 ) a second set of pixel values from respective pixel locations in the estimated direction ( 140 ) from the first pixel location ( 120 ); computing ( 350 ) a third set of pixel values from the second set of pixel values; and assigning ( 360 ) pixel values to pixel locations of at least a part of the region( 110 ) comprising pixel locations of unassigned pixel values using the third set of pixel values.