[Koha] Error in Uploading Patron Images

Dear Colleagues, I have installed koha on several occasions before. I helped a colleague make the installation once again yesterday and followed the exact steps I used before. However, I am now experiencing an error when I try to import patron Images and the error I get is below *"Can't locate object method "newFromPng" via package "GD::Image" at /usr/local/lib/perl/5.8.8/GD/Image.pm line 81.*" Has anyone handled this error before. Kindly help me resolve this problem. Thanks you Anselm Olweny Teaching Assistant EASLIS, Makerere University.