Denoise algorithm in weave - c++

Question

I'm making a program that denoises an image. It does this by converting the RGB values of the image into it's HSI values, then operates on the HSI values and converts them back into RGB. My problem is that for some reason, quite a bit of the image gets the wrong colors after the denoising (the denoising itself works).
I'm at a standstill now with no ideas what is causing it (except that it's probably in the conversion process between RGB and HSI somewhere), so do any of you fine gentlemen/women have any idea? Here's an example of a picture that turned out wrong (all the extra green color):
These are the formulas:
FYI the formula has one error, which is that if R==G==B then H and S should be set to 0. You'll see that in the code.
Here's my weave code for the two different conversion processes (RGB>HSI, HSI>RGB). Cos and acos values need to be in degrees, hence the addition 180/pi and pi/180. The i in G[i], etc. just refers to the pixel being converted (it loops through all the pixels in the picture).
To HSI:
translateToHSI = r"""
for (int i=0; i<(m*n); i++)
{
I[i] = (R[i]+G[i]+B[i])/3;
if (I[i] == 0)
{
S[i] = 0;
}
else
{
float fl = fmin(R[i], G[i]);
fl = fmin(fl, B[i]);
S[i] = 1-(fl/I[i]);
}
float func = (R[i]-(G[i]/2.0)-(B[i]/2.0))/sqrt((R[i]*R[i])+(G[i]*G[i])+(B[i]*B[i])-(R[i]*G[i])-(R[i]*B[i])-(G[i]*B[i]));
if (R[i]==G[i] && G[i] == B[i])
{
H[i] = 0;
S[i] = 0;
}
else if (G[i]<B[i])
{
H[i] = 360-(acos(func)*180.0/3.14159265);
}
else
{
H[i] = acos(func)*180.0/3.1459265;
}
}
"""
to RGB:
translateToRGB = r"""
for (int i=0; i<(m*n); i++)
{
if (H[i] == 0)
{
R[i] = I[i]+2*I[i]*S[i];
G[i] = I[i]-I[i]*S[i];
B[i] = I[i]-I[i]*S[i];
}
else if (H[i] < 120)
{
float func = cos(H[i]*3.14159265/180)/cos(60-H[i]*3.14159265/180);
R[i] = I[i]+I[i]*S[i]*func;
G[i] = I[i]+I[i]*S[i]*(1-func);
B[i] = I[i]-I[i]*S[i];
}
else if (H[i] == 120)
{
R[i] = I[i]-I[i]*S[i];
G[i] = I[i]+2*I[i]*S[i];
B[i] = I[i]-I[i]*S[i];
}
else if (H[i] < 240)
{
float func = cos((H[i]-120)*3.14159265/180)/cos((180-H[i])*3.1459265/180);
R[i] = I[i]-I[i]*S[i];
G[i] = I[i]+I[i]*S[i]*func;
B[i] = I[i]+I[i]*S[i]*(1-func);
}
else if (H[i] == 240)
{
R[i] = I[i]-I[i]*S[i];
G[i] = I[i]-I[i]*S[i];
B[i] = I[i]+2*I[i]*S[i];
}
else
{
float func = cos((H[i]-240)*3.14159265/180)/cos((300-H[i])*3.14159265/180);
R[i] = I[i]+I[i]*S[i]*(1-func);
G[i] = I[i]-I[i]*S[i];
B[i] = I[i]+I[i]*S[i]*func;
}
}
"""

Answer 1

So I wrote the following code
#include <iostream>
#include <math.h>
void toHSI(float R, float G, float B, float& H, float& S, float& I) {
I = (R+G+B)/3;
if (I == 0)
{
S = 0;
}
else
{
float fl = fmin(R, G);
fl = fmin(fl, B);
S = 1-(fl/I);
}
float func = (R-(G/2.0)-(B/2.0))/sqrt((R*R)+(G*G)+(B*B)-(R*G)-(R*B)-(G*B));
if (R==G && G == B)
{
H = 0;
S = 0;
}
else if (G<B)
{
H = 360-(acos(func)*180.0/3.14159265);
}
else
{
H = acos(func)*180.0/3.1459265;
}
}
void toRGB(float H, float S, float I, float& R, float& G, float& B) {
if (H == 0)
{
R = I+2*I*S;
G = I-I*S;
B = I-I*S;
}
else if (H < 120)
{
float func = cos(H*3.14159265/180)/cos(60-H*3.14159265/180);
R = I+I*S*func;
G = I+I*S*(1-func);
B = I-I*S;
}
else if (H == 120)
{
R = I-I*S;
G = I+2*I*S;
B = I-I*S;
}
else if (H < 240)
{
float func = cos((H-120)*3.14159265/180)/cos((180-H)*3.1459265/180);
R = I-I*S;
G = I+I*S*func;
B = I+I*S*(1-func);
}
else if (H == 240)
{
R = I-I*S;
G = I-I*S;
B = I+2*I*S;
}
else
{
float func = cos((H-240)*3.14159265/180)/cos((300-H)*3.14159265/180);
R = I+I*S*(1-func);
G = I-I*S;
B = I+I*S*func;
}
}
int main() {
for (int r = 0; r < 255; r += 10) {
for (int g = 0; g < 255; g += 10) {
for (int b = 0; b < 255; b += 10) {
float r1, g1, b1, h, s, i;
toHSI(r, g, b, h, s, i);
toRGB(h, s, i, r1, g1, b1);
if (fabs(r - r1) > 5 || fabs(g - g1) > 5 || fabs(b - b1) > 5) {
std::cout << r << ' ' << g << ' ' << b << " --> "
<< h << ' ' << s << ' ' << i << " --> "
<< r1 << ' ' << g1 << ' ' << b1 << std::endl;
}
}
}
}
}
Demo for convenience
The first lines of output are:
0 20 0 --> 119.835 1 6.66667 --> -9.17128 29.1713 0
0 30 0 --> 119.835 1 10 --> -13.7569 43.7569 0
0 40 0 --> 119.835 1 13.3333 --> -18.3426 58.3426 0
0 50 0 --> 119.835 1 16.6667 --> -22.9282 72.9282 0
0 60 0 --> 119.835 1 20 --> -27.5138 87.5138 0
Now you can debug this code with any of the values which give wrong results and find where the bug is.