## Implementing an algorithm, math error.

Hi, im making a program that can convert RGB to HSI. Hue, Saturation and Intensity.
HSI is abit more complex than HSV and HSB.
Im using OpenCV for doing it. But i however cant used the premade funcs in opencv.

Im loading my input image into a matrix, and im dragging out the rgb-info i want.
Done in a loop for x,y.

i have succesfully made the conversion of S and I, but im stuggling alot with H.

This is the formulas for the conversion: Code equivalent:
Code:
```float H, S, I;
I = ((R+G+B)/3);
float min=R;
if (min>G) min=G;
if (min>B) min=B;
S = 1-(3*(min/(R+G+B)));```
H, is more complex though. It rely on whether (G>=B) is true or false.
Code:
```if (G>=B)
{
H = acos((1/2)*(((R-G)+(R-B))/(sqrt(((R-G)*(R-G))+((R-B)*(G-B))))));
cout << "without 360-part H = " << H << endl; //writes the S value
}
else
{
H = 360-(acos((1/2)*(((R-G)+(R-B))/(sqrt(((R-G)*(R-G))+((R-B)*(G-B)))))));
cout << "360-part H = " << H << endl; //writes the S value
}```
when i manually plug in some static RGB values to test if the results is correct, then with (0,255,0) Green i get this:
I=85
S=1
H=1.5708
and the correct results would be:
I=85
S=1
H=120

so my question is, have I implemented it wrong in c++ ?
and how is the right way?

also i have found another formula of the H-part, but i think its the same, though im not sure how to implement the squared part. but its on this link: http://www5.informatik.tu-muenchen.d...csc/COL_24.htm