Colour Difference DeltaE 2000 - algorithm

Question

I am trying to Calculate the CIE Colour Difference DeltaE 2000 based on DE2000 Formula. I have done as per the formula provided in the website, but I am getting strange delta E values. I am confused where I have gone wrong. I have checked manytimes but I am not able to find the mistake.Can someone tell me which part of my code has problem.
function DE_2K = CIEDE2000(Lab1,Lab2)
labuno=Lab1
labdos=Lab2
L1=labuno(1)
a1=labuno(2)
b1=labuno(3)
L2=labdos(1)
a2=labdos(2)
b2=labdos(3)
%*******************************************************************
% Definition for CIE DE2000
%*******************************************************************
L_bar_dash=(L1+L2)/2;
C1 = sqrt((a1)^2+(b1)^2)
C2 = sqrt((a2)^2+(b2)^2)
C_bar = (C1+C2)/2
G = (1 -sqrt(((C_bar)^7)/((C_bar)^7+(25)^7))/2)
a1_dash = a1*(1+G)
a2_dash = a2*(1+G)
C1_dash = sqrt((a1_dash)^2+(b1)^2)
C2_dash = sqrt((a2_dash)^2+(b2)^2)
C_bar_dash = (C1_dash + C2_dash)/2
if (radtodeg(atan(b1/a1_dash)) >= 0 ) h1_dash = radtodeg(atan(b1/a1_dash))
else h1_dash = radtodeg(atan(b1/a1_dash)) + radtodeg(2*pi)
end
if (radtodeg(atan(b2/a2_dash)) >= 0 ) h2_dash = radtodeg(atan(b2/a2_dash))
else h2_dash = radtodeg(atan(b2/a2_dash)) + radtodeg(2*pi)
end
if ((h1_dash - h2_dash) > radtodeg(pi)) H_bar_dash = (h1_dash + h2_dash + radtodeg(2*pi))/2
else H_bar_dash = (h1_dash + h2_dash)/2
end
T = 1 - 0.17*radtodeg(cos(H_bar_dash-radtodeg(pi/6)))+0.24*radtodeg(cos(2*H_bar_dash))+0.32*radtodeg(cos(3*H_bar_dash + radtodeg(pi/30)))- 0.20*radtodeg(cos(4*H_bar_dash + 63))
if ((abs(h2_dash - h1_dash)) <= radtodeg(pi)) DE_h_dash = h2_dash - h1_dash
elseif(abs(h2_dash - h1_dash) > radtodeg(pi) && h2_dash <= h1_dash) DE_h_dash = h2_dash - h1_dash + radtodeg(2*pi)
else DE_h_dash = h2_dash - h1_dash - radtodeg(2*pi)
end
DE_L_dash = L2 - L1
DE_C_dash = C2_dash - C1_dash
DE_H_dash = 2 * sqrt(C1_dash * C2_dash) * radtodeg(sin(DE_h_dash/2))
S_L = 1 + ((0.015 * (L_bar_dash - 50)^2)/sqrt(20 + (L_bar_dash - 50)^2))
S_C = 1 + (0.045 * C_bar_dash)
S_H = 1 + (0.015 * C_bar_dash * T)
DE_angle = 30 * exp( - ((H_bar_dash - 275)/25)^2)
R_C = 2 * sqrt((C_bar_dash)^7/((C_bar_dash)^7 + (25)^7))
R_T = - R_C * radtodeg(sin(2 * DE_angle))
K_L = 1
K_C = 1
K_H = 1
DE_2K = sqrt( (DE_L_dash/(K_L * S_L))^2 + (DE_C_dash/(K_C * S_C))^2 + (DE_H_dash/(K_H * S_H))^2 + (R_T * (DE_C_dash/(K_C * S_C)) * (DE_H_dash/(K_H * S_H))))
end

Answer 1

There are some problems in your calculations:
a) if ((h1_dash - h2_dash) > radtodeg(pi)) : don't you need to take the abs of this?
b) 20*radtodeg(cos(4*H_bar_dash + 63) : you need -63 here
c) I assume your if-else structure correctly handles the three cases; you may need to check that:
....else DE_h_dash = h2_dash - h1_dash - radtodeg(2*pi)
d) sin is a number not in degrees, not in radians so no need to convert here:
radtodeg(sin(DE_h_dash/2))
e) same here: radtodeg(sin(2 * DE_angle))
f) I assume cos/sin take degrees; you many need to double check what is degrees what is radians everywhere.