Wildfire visualization - blend function

Hello everyone,

I am going through the Wildfire visualization script from Pierre Markuse and don’t fully understand the blend function.

function blend(bArr1, bArr2, opa1, opa2) {
return bArr1.map(function(num, index) {
return (num / 100 * opa1 + bArr2[index] / 100 * opa2);

Assuming that index is the index of the image bands (3 band image), then what is num? Any hint would be very much appreciated.

Thank in advance, Philipp

We are blending an array containing multiple (here 3) values, num denotes the actual value of the array at position index.

Thank you for the explanation!