Unity 3d C# Script needed: Texture Sheet from Camera Phone - Cross Platform Android/Iphone

I need a script written in C# for the Unity game engine. It's for a cross-platform mobile project, so it needs to work for both Iphone and Android phones. 1. The script needs to use the phone's camera. 2. It should have an option to switch between front and back cameras. 3. It should take the center of the image (where the user's face should be) and write it to a texture atlas/sprite sheet (example shown in attached picture). 4. save the texture atlas to a place on the device that the application can access. 5. It would be nice to have a way to choose (within the code) what row and column I'm writing the image to, but if it's too difficult scratch it. 6. Need a way to choose the texture atlas size (1024x1024, 2048 x 2048, etc.). 7. The resulting camera image needs to be scaled to fit into the sprite sheet/texture atlas. 8. A way to choose the number of rows and columns would be nice. 9. Needs to work on both iphone and android phones. If you need clarification feel free to ask me any questions.