All you need is a photo of a person as a JPG file. A one-megapixel photo is more than sufficient to make your papercraft look very good, but you can also create beautiful papercrafts with photos of smaller size.
You will achieve the best results if you use a photo of a person taken from the front.
Shots from the side will provide less optimal results. The person’s head should fill the photo as much as possible, so the use of a close-up is recommended.