Chroma key with OpenCL and Lode's QuickCG

Question

in my project I'm using OpenCL with Lode's QuickCG (documentation here).

We are having a problemam that, we want to identify when a pixel matches a green chroma key color and then draw the second image instead (background).

Here's the kernel code:

__kernel void convolute(__global float* inputImage1, __global float* inputImage2, __global float* outputImage, __global float* filter, int width, int height ,float bias, float factor)
{
    int x = get_global_id(0);
    int y = get_global_id(1);

    float sumR = 0;
    float sumG = 0;
    float sumB = 0;

    float cR = 40.0;
    float cG = 250.0;
    float cB = 20.0;

    float tolerance = 100.0;
    
    
    if ( (x >= 0) &&
         (x < width) &&
         (y >= 0) &&
         (y < height)) {

        float pR = inputImage1[x * 3 + y * width * 3 + 0];
        float pG = inputImage1[x * 3 + y * width * 3 + 1];
        float pB = inputImage1[x * 3 + y * width * 3 + 2];     

        float d = (sqrt(pow((cR - pR), 2) + pow((cG - pG), 2) + pow((cB - pB), 2)));

        if (d <= tolerance) {
            sumR += inputImage2[x * 3 + y * width * 3 + 0];
            sumG += inputImage2[x * 3 + y * width * 3 + 1];
            sumB += inputImage2[x * 3 + y * width * 3 + 2];
        }
        else {
            sumR += pR;
            sumG += pG;
            sumB += pB;
        }
    }

    outputImage[y * width * 3 + x * 3] = min_max(sumR);
    outputImage[y * width * 3 + x * 3 + 1] = min_max(sumG);
    outputImage[y * width * 3 + x * 3 + 2] = min_max(sumB);
}

We tried in two ways, first is verifying just the green color (just for a test) and using this formula that my professor gave

formula for chroma key

Both ways we could not succeed, I believe that the probleam is that the values inside the kernel code are to low, so the green is not going to be 255, actualy with a if statement, we verified that is something around 1e-46

Is there a method that can convert this to a compreensible integer or something that we can work with?