(define-library (pnm image)
  (export make-image
          image?
          image-type
          image-width
          image-height
          image-maxval
          image-data
          image-pixel-getter
          image-pixel-setter
          image-ref
          image-set!)
  (import (scheme base)
          (scheme case-lambda))
  (begin
    (define-record-type <image>
      (make-image type width height maxval data pixel-getter pixel-setter)
      image?
      (type image-type)
      (width image-width)
      (height image-height)
      (maxval image-maxval)
      (data image-data)
      (pixel-getter image-pixel-getter)
      (pixel-setter image-pixel-setter))

    (define (image-ref image x y)
      ((image-pixel-getter image) x y))

    (define image-set!
      (case-lambda
        ((image x y v)
         ((image-pixel-setter image) x y v))
        ((image x y r g b)
         ((image-pixel-setter image) x y r g b))))))