What is range of values for color samples for HDR?

What would be the range of color sample values in kernels for HDR (the example shown of invert for non-HDR video, what would be the correct code for HDR):
extern “C” float4 ColorInverter(coreimage::sample_t s, coreimage::destination dest) {
return float4(1.0 - s.r, 1.0 - s.g, 1.0 - s.b, 1.0);
}