如何在C＃中使用两种颜色之间的rgb差异以找到最接近的匹配？

Question

I have a code that gets the closest color based on RGB difference, but with dark colors like dark blue, it returns black instead of "dark blue". Can u guys help me finding out what's happening?

This is the code that calculates RGB difference between two colors:

int ColorDiff(Color c1, Color c2)
{
    return (int)Math.Sqrt((c1.R - c2.R) * (c1.R - c2.R)
                        + (c1.G - c2.G) * (c1.G - c2.G)
                        + (c1.B - c2.B) * (c1.B - c2.B));
}

This code gets the closest color on the list (the one that has less difference between RGB):

int encontrarCor(List<Color> colors, Color target)
{
    var colorDiffs = colors.Select(n => ColorDiff(n, target)).Min(n => n);
    return colors.FindIndex(n => ColorDiff(n, target) == colorDiffs);
}

What I think is happening is that, as you can see in the first code, it does: (c1.R - c2.R) * (c1.R - c2.R), so if one of these substrates is equal to 0, the whole product is gonna be 0, so returns black, cause RGB code of black is 0,0,0.

I've tried to make myself as clear as possible, sorry if is a little bit confused.

Answer 1

I don't get the point of the square root and multiplications, but the differences should be positive:

int RGBdiff(Color c1, Color c2)
{
    return Math.Abs(c1.R - c2.R) + Math.Abs(c1.G - c2.G) + Math.Abs(c1.B - c2.B);
}

Color ClosestColor(Color target, IEnumerable<Color> colors)
{
    return colors.Min(c => Tuple.Create(RGBdiff(c, targert), c)).Item2;
}

Note that more than one color can have the same difference.