Package ppm 
import "github.com/lmittmann/ppm"
Package ppm implements a Portable Pixel Map (PPM) image decoder and encoder. The supported image color model is color.RGBAModel.
The PPM specification is at http://netpbm.sourceforge.net/doc/ppm.html.
func Decode
func Decode(r io.Reader) (image.Image, error)
Decode reads a PPM image from Reader r and returns it as an image.Image.
func DecodeConfig
func DecodeConfig(r io.Reader) (image.Config, error)
DecodeConfig returns the color model and dimensions of a PPM image without decoding the entire image.
func Encode
func Encode(w io.Writer, img image.Image) error
Encode writes the Image img to Writer w in PPM format.