something like snapseed is good for editing them playing with sharpness contrast etc can sometimes have the desired effect, the camera with the ipad 2 is pretty bad to be honest.
where ever possible try and take your pictures in good natural light, you will be surprised with the difference staging your photos can be.
The camera in your iPad 2 was never intended to take true camera quality pictures, and in low light the resolution is bad at best. The camera itself has less 1 megapixel resolution.
There are certainly photo editing applications you can purchase, but honestly, if the picture is grainy, they will not likely offer much of a fix, if any.
I have the New iPad and while the resolution is now at 5 megapixel, it's still not up to digital camera standards, nor do I expect it to be. Camera on iPad was really designed to handle Facetime calls.
Sorry if this is not the answer you were looking for......