This is one of my tips for you, abut how to edit your photo or the simple way to edit your image. Talking about photo editing, i usually use gimp (GNU Image Manipulation Program) as my favourite photo editor. before i use this opensource software, i use PS 7 as my photo editor, but after i knew that my Photoshop is illegal (pirated edition), so i migrate to GIMP ...first time maybe it's difficult for me...but after tweak GIMP as photoshop, hmm...i very satisfied and happy. this is the best photo editor for me (in opensource way).
it's better for you if you know how the Editing methods in computer graphics, because it is very useful for us.
In General, most of editing methods suffer from linearization problems: methods which use translational constraints allow insensitive to rotations, whereas methods relying on rotational constraints exhibit insensitivity to translations. To solve this little problem, we can review methods use skeleton-based techniques, multi-step approaches, or iterative approaches. Most linear deformation methods rely on a triangle mesh representation. although deforming a surface model may cause local self intersections and shrinking effects. To prevent such artifacts, some methods use a volumetric structure as basis for the linear deformation. Another class of approaches is able to manipulate an object while guaranteeing volume preservation by defining deformations based on vector fields. Although it enables the definition of advanced implicit deformation tools, it is still hard to construct vector fields that satisfy the user-defined constraints.