;;; File:
;;;   chrome.scm
;;; Author:
;;;   Samuel A. Rebelsky
;;; Summary:
;;;   An attempt to get a "chrome" effect on an image.
;;; Citation:
;;;   Based on chrome.java by Seth Holiday.  Rewritten in Scheme and
;;;   generalized by SamR

(define rgb-increase-contrast
  (lambda (color)
    (rgb-map color (lambda (comp) (- (* 1.5 comp) 64)))))

(define rgb-decrease-contrast
  (lambda (color)
    (rgb-map color (lambda (comp) (+ (* .5 comp) 64)))))

(define rgb-plazma
  (lambda (color)
    (let ((red (rgb-red color))
          (green (rgb-green color))
          (blue (rgb-blue color)))
      (rgb-new (+ red (if (< red 128) -30 30))
               (+ green (if (< green 128) -20 40))
               (+ blue (if (< blue 128) -40 20))))))

(define rgb-simple-grey
  (lambda (color)
    (let ((comp (/ (+ (rgb-red color) (rgb-green color) (rgb-blue color)) 3)))
      (rgb-new comp comp comp))))

(define chrome1 (o rgb-increase-contrast
                   rgb-decrease-contrast
                   rgb-increase-contrast
                   rgb-increase-contrast
                   rgb-increase-contrast
                   rgb-simple-grey
                   rgb-increase-contrast
                   rgb-increase-contrast
                   rgb-plazma
                   rgb-plazma
                   rgb-plazma
                   rgb-plazma))

(define chrome2 (o rgb-increase-contrast
                   rgb-decrease-contrast
                   rgb-increase-contrast
                   rgb-increase-contrast
                   rgb-increase-contrast
                   rgb-increase-contrast
                   rgb-increase-contrast
                   rgb-plazma
                   rgb-plazma
                   rgb-plazma
                   rgb-plazma))