Question

im writing a program to compare two images against each other based on color and im using the Euclidean distance algorithm however when i run it and pass in two images i get one distance and then when i pass in the same images but the other way round i get a completely different set of results.

is this normal or should the answers be the same?

The statement I’m using to compute the Euclidean distance is:

distance = (int) Math.sqrt(   (rgb1.getR()-rgb2.getR())^2
                            + (rgb1.getG()-rgb2.getG())^2
                            + (rgb1.getB()-rgb2.getB())^2
                          );

Answer 1

Looking at the code you posted, it looks your RGB values are ints. However, the ^ operator is not the power operator, but XOR (exclusive-OR) – a bitwise operation. So in order to calculate the squares correctly, use regular multiplication – e.g., use a temporary variable int deltaR = rgb1.getR()-rgb2.getR(); and then in the formula write deltaR*deltaR instead of the ^ operator. Your RGB values will probably be in 0 to 255 range, so there shouldn’t be overflow issues. Alternatively, you could use Math.pow(rgb1.getR()-rgb2.getR(),2) etc. in the formula.