We Sell Mobile Phone Cover on Marketplace Like Amazon. I would explain how the process work which would give you an idea on the requirement.
1. We select high resolution Wallpaper from Internet and place it in a folder [example of Wallpaper uploaded]
2. The Image is converted to a specific size and 300 DPI so that it can be used to print on white mobile case using 3D sublimation technology Printer. First thing we would need the Wallpaper/images to be converted to specific size and 300 resolution for printing [Printable converted image attached]. This exercise should be pretty straightforward. We can place the wallpapers in one folder and the script should process the image and covert (in bulk) it to Printable format into another folder as JPG/PNG.
3. The printable image can be used by the printing vendor to print the design/picture on white case using 3d sublimation machine [process in factory, No support required]
4. Now to sell this on market place we would need to show the images as product to the users on mobile models, for example Iphone 5 case with the image on it appearing as a mobile cover. This needs to have 2 images front view and perspective view. Example http://www.amazon.in/Superhero-Deadpool-Iphone-Printed-Premium/dp/B01MT4N2MO/ref=sr_1_1?ie=UTF8&qid=1483554004&sr=8-1&keywords=IPH5DP1
5. For creating the product image we would need to place the image (printable image) on Mobile phone PSD mock-up template for several models. The mock-up are available for most of the latest model on below URL [url removed, login to view]
6. Step five is manually done for each model and is simple. We import the printable image on mock-up template Place the image on mockup export it as JPG. When we try doing this for all model of phone the process consumes a lot of time. We would need this to be automated where the images are picked up from printable image folders and are placed on each mock-up mobile models and the output is saved in different folder with proper naming to identify the final output (which model the case is of). If this can only be done for front look this should be fine, perspective view is an additional advantage
7. To Sum up We need the Wallpaper to be converted into printable image of specific size and DPI, Printable image to be place on mobile case mock-up and output as a case picture for available phone models/templates
8. For this if we can have a front end kind of form, it would be easy to work on automation (not mandatory though)