imghdr

Library that determines the type of image contained in a file or byte stream, basically clone of the Python imghdr module.

Documentation is here.

Examples

Check a file directly:

extern crate imghdr;

fn main() {
    match imghdr::open("/path/to/image.png") {
        Ok(imghdr::Type::Png) => println!("Yep, it is a PNG"),
        _ => println!("Nope, it is definitely not a PNG"),
    }
}

Or check a byte stream:

extern crate imghdr;

fn main() {
    let mut file = File::open("/path/to/image.png").unwrap();
    let mut content: Vec<u8> = vec![];
    file.read_to_end(&mut content).unwrap();

    match imghdr::what(content.as_slice()) {
        Some(imghdr::Type::Jpg) => println!("And this is a Jpeg"),
        _ => println!("Can a Png, Bmp or other file format"),
    }
}