Give rgb value
r=
g=
b=
double R, G, B;
R = (double) r;
G = (double) g;
B = (double) b;

R = 1.0 - (R / 255.0);
G = 1.0 - (G / 255.0);
B = 1.0 - (B / 255.0);

double C, M, Y, K;
if (R < G)
K = R;
else
K = G;
if (B < K)
K = B;

C = (R - K)/(1.0 - K);
M = (G - K)/(1.0 - K);
Y = (B - K)/(1.0 - K);

C = (C * 100) + 0.5;
M = (M * 100) + 0.5;
Y = (Y * 100) + 0.5;
K = (K * 100) + 0.5;