image取り扱い

●画像の保存
http://www.iphonedevsdk.com/forum/iphone-sdk-development/6227-saving-retrieving-images-app.html

●UIImage をPNGかJPGで保存
http://iphonedevelopertips.com/data-file-management/save-uiimage-object-as-a-png-or-jpeg-file.html