I have worked on photo editors and i am pretty decent in building camera ans photo viewer apps.
It wont be a difficult task to develop this project.
These are your requirements:
1. Photo editor searches gallery to import photo to edit.
2. Provide photo editing.
3. Save it to particular folder in gallery.
What i can provide:
1. Photos can be imported from gallery.
2. Photo editing options such as cropping,red eye,straighten,rotate,flip,sharpen ,color effects - warmth,saturation,B&W,negative.
3. A separate gallery inside app to save these edited pictures.
4. Facebook sharing option.