c - Are there known implementations of the CIEDE2000 or CIE94 Delta-E color difference calculation algorithm? -



c - Are there known implementations of the CIEDE2000 or CIE94 Delta-E color difference calculation algorithm? -

i need calculate delta-e distance between 2 colors. algorithm 2 colors in cielab color space looks this:

are there known open-sourced implementations of algorithm? it's not hard implement, lastly effort of implementing color-space conversion algorithm i'd prefer not re-develop wheel when it's on road , tested.

ciede2000 nice , more accurate, might overkill on iphone. cie94 fine guess.

i typed in equation (for mutual lisp code see @ bottom) , ran few random evaluations. parameters listed in order: l*1 a*1 b*1 l*2 a*2 b*2 deltae*

i'm not sure results correct. if code gives same results, it's sufficient.

((53.0 0.65 0.15 33.0 -0.45 -0.1 20.03112) (42.0 -0.3 0.1 74.0 -0.2 -0.15 32.001118) (12.0 -1.0 -0.45 32.0 0.3 0.9 20.084782) (94.0 -0.1 -0.55 77.0 0.5 0.45 17.03928) (75.0 -0.8 0.35 46.0 -0.6 -0.85 29.02483) (83.0 -0.65 -0.7 67.0 0.75 0.0 16.074173) (70.0 -0.7 0.9 54.0 0.35 -0.95 16.13608) (81.0 0.45 -0.8 53.0 -0.35 0.05 28.023375) (40.0 -0.2 -0.65 25.0 -1.0 0.8 15.088856) (66.0 0.85 -0.7 93.0 0.55 0.15 27.014244) (44.0 -0.5 0.5 23.0 -0.9 0.5 21.00363) (67.0 0.4 0.25 42.0 -0.25 0.6 25.010727) (32.0 0.6 0.55 86.0 0.0 0.25 54.003925) (96.0 -0.15 -0.9 87.0 0.25 -0.3 9.027307) (100.0 -0.6 0.3 61.0 -0.25 -0.75 39.015385) (2.0 -0.2 -0.65 73.0 -0.3 0.65 71.01173) (74.0 0.1 -0.65 96.0 -0.5 0.8 22.05474) (22.0 -0.3 -0.85 64.0 -0.65 -0.95 42.0015) (73.0 -0.35 0.3 38.0 0.25 -1.0 35.02875) (91.0 0.6 0.45 82.0 -0.25 0.2 9.042115))

and here source code (tested in sbcl):

;; http://en.wikipedia.org/wiki/hypot thats not necessary if numbers ;; not float , if float values of l*, a* , ;; b* bound tiny range (defun hypot (x y) "compute hypotenuse, prevent overflow." (declare (type number x y) (values number &optional)) (let ((ax (abs x)) (ay (abs y))) (if (or (< ax 1e-6) (< ay 1e-6)) (sqrt (+ (* ax ax) (* ay ay))) (if (< ay ax) (* ax (sqrt (1+ (expt (/ y x) 2)))) (* ay (sqrt (1+ (expt (/ x y) 2)))))))) #+nil (list (hypot 1 0) (hypot 0 1) (hypot (sqrt 2) (sqrt 2)) (hypot 2 10000)) ;; http://www.devmaster.net/forums/archive/index.php/t-12680.html (defun hypot3 (x y z) (hypot (hypot x y) z)) (defun delta-e*-94 (l1 a1 b1 l2 a2 b2 &key (application :graphic-arts)) "distance in cie l* a* b* color space." (declare (type number l1 a1 b1 l2 a2 b2) (type (member :graphic-arts :textiles) application) (values number &optional)) (destructuring-bind (kl k1 k2) (ecase application (:graphic-arts '(1 .045 .015)) (:textiles '(2 .048 .014))) (let* ((delta-l (- l1 l2)) (c1 (hypot a1 b1)) (c2 (hypot a2 b2)) (delta-c (- c1 c2)) (delta-a (- a1 a2)) (delta-b (- b1 b2)) (delta-h (sqrt (+ (expt delta-a 2) (expt delta-b 2) (* -1 (expt delta-c 2))))) (l/k (/ delta-l kl)) (c/k (/ delta-c (1+ (* k1 c1)))) (h/k (/ delta-h (1+ (* k2 c1))))) (hypot3 l/k c/k h/k)))) #+nil ;; test runs (labels ((rl () ;; random number 0..100 inclusive (random 101)) (r- () (/ (- (random 40) 20) 20)) (r3 () (list (rl) (r-) (r-)))) (loop below 20 collect (destructuring-bind (l b) (r3) (destructuring-bind (ll aa bb) (r3) (mapcar #'(lambda (x) (* 1s0 x)) (list l b ll aa bb (delta-e*-94 l b ll aa bb))))))) #+nil ;; illustration test run ((80.0 0.85 0.35 13.0 0.4 -0.8 67.01107) (11.0 0.25 -0.35 66.0 0.45 0.15 55.002594) (74.0 -0.55 0.45 98.0 0.7 -0.85 24.066118) (37.0 -0.3 0.35 60.0 0.55 -0.3 23.02452) (20.0 -0.85 0.5 20.0 -0.25 0.1 0.6907073) (23.0 0.25 -0.05 15.0 0.55 -0.8 8.039892) (29.0 -0.55 0.05 9.0 -0.2 -0.8 20.020708) (11.0 0.55 -0.45 60.0 0.9 -0.15 49.00211) (70.0 0.5 -0.15 66.0 -0.8 0.85 4.3169336) (18.0 -0.5 0.55 49.0 0.5 -0.25 31.025839) (27.0 -0.95 0.3 43.0 -0.1 0.2 16.021187) (5.0 -0.4 0.5 70.0 -0.75 -0.75 65.012665) (9.0 -1.0 -0.2 66.0 0.4 0.05 57.01702) (10.0 0.25 -0.75 13.0 -0.85 -0.75 3.1900785) (16.0 -0.65 -0.4 31.0 -0.6 -0.5 15.000405) (90.0 0.4 0.1 18.0 -0.6 -0.85 72.01298) (92.0 0.4 0.1 31.0 -0.7 0.2 61.009853) (99.0 -0.7 -0.5 40.0 -0.9 0.35 59.006287) (40.0 0.95 -0.2 62.0 -0.7 -0.25 22.06002) (16.0 0.5 0.7 35.0 0.35 -0.45 19.03436))

c algorithm math image-processing colors

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