o :ήc1@s~dZddlZddlmZddlmZmZddd Zdd d Z dd dddZ dd dddZ dd dddZ d dddZ dS)a Functions for calculating the "distance" between colors. Implicit in these definitions of "distance" is the notion of "Just Noticeable Distance" (JND). This represents the distance between colors where a human can perceive different colors. Humans are more sensitive to certain colors than others, which different deltaE metrics correct for with varying degrees of sophistication. The literature often mentions 1 as the minimum distance for visual differentiation, but more recent studies (Mahy 1994) peg JND at 2.3 The delta-E notation comes from the German word for "Sensation" (Empfindung). Reference --------- https://en.wikipedia.org/wiki/Color_difference N)_supported_float_type)lab2lch_cart2polar_2piTcCsTt|}t|}|rt|j|jg}ntj}|j|dd}|j|dd}||fS)NF)copy)npasarrayrdtypefloat64astype)lab1lab2 allow_float32 float_dtyper 1`` are "different" for the given scale factors. Parameters ---------- lab1 : array_like reference color (Lab colorspace) lab2 : array_like comparison color (Lab colorspace) channel_axis : int, optional This parameter indicates which axis of the arrays corresponds to channels. .. versionadded:: 0.19 ``channel_axis`` was added in 0.19. Returns ------- dE : array_like distance between colors `lab1` and `lab2` Notes ----- deltaE_cmc the defines the scales for the lightness, hue, and chroma in terms of the first color. Consequently ``deltaE_cmc(lab1, lab2) != deltaE_cmc(lab2, lab1)`` References ---------- .. [1] https://en.wikipedia.org/wiki/Color_difference .. [2] http://www.brucelindbloom.com/index.html?Eqn_DeltaE_CIE94.html .. [3] F. J. J. Clarke, R. McDonald, and B. Rigg, "Modification to the JPC79 colour-difference formula," J. Soc. Dyers Colour. 100, 128-132 (1984). Trrrr&NriYgQ?r=g ףp= ?g?#r>ilg'1Z?gB>٬?g?gPs?g"~j?g|a2U?g<,Ԋ?rr) rrrrr'whererErJrFrGrHrr()r rr+r*rrr.rPr r/rQr1r0r2r]c1_4Fr3r4r5r6rrr deltaE_cmcs*-"  "rkc Cst||gtjk}t||dd\}}tj||dddd\}}tj||dddd\}}t||}t||} || ||||} d| } |rR| tj} | S)asquared hue difference term occurring in deltaE_cmc and deltaE_ciede94 Despite its name, "dH" is not a simple difference of hue values. We avoid working directly with the hue value, since differencing angles is troublesome. The hue term is usually written as: c1 = sqrt(a1**2 + b1**2) c2 = sqrt(a2**2 + b2**2) term = (a1-a2)**2 + (b1-b2)**2 - (c1-c2)**2 dH = sqrt(term) However, this has poor roundoff properties when a or b is dominant. Instead, ab is a vector with elements a and b. The same dH term can be re-written as: |ab1-ab2|**2 - (|ab1| - |ab2|)**2 and then simplified to: 2*|ab1|*|ab2| - 2*dot(ab1, ab2) Frrrrrr)rrfloat32rrrBr ) r rrinput_is_float_32rrr!r"r.r/termoutrrrr'fs   r')T)r)rrrr$r%)rrr)rr)__doc__numpyr _shared.utilsr colorconvrrrr#r7rcrkr'rrrrs   ! OI