[Closed] Swap green for blue wisely

Super interesting guys, I never realized that a simple color change wouldn’t be enough with regards to intensity and the above reads are enlightening (pun intended)

image.jpg837×267 29.2 KB

that’s the difference between “desaturate” and “grayscale”

That looks pretty good to me.
It may not be numerically correct but visually it looks as good as it can be.

Here my last code, now optimized.

fn SwapBlueGreenChannels colour =
(
	l1 = (colour.g^2 * 5.0 + colour.b^2)+1.0
	l2 = (colour.b^2 * 5.0 + colour.g^2)+1.0
	
	delta = sqrt (l1 / l2)
	
	b = colour.g * delta
	
	if b > 255 then
	(
		g = sqrt ((l1 - 65025)/5.0)
		b = 255
	)else(
		g = colour.b * delta
	)
	
	return (color colour.r g b)
)

“+1.0” so as not to divide by ZERO for sure?

Yes. I mean no, it’s there because it has secret powers.
Well, I didn’t want to use int() or “if”. Do we have other options?
I know, it looks horrible!

it makes sense anyway:
if (c.g == 0 and c.b == 0) or (c.g == c.b) return c

here is c++

AColor SwapGreenBlue(const AColor colour, double R = 0.299, double G = 0.587, double B = 0.114)
{
	double r(colour.r);
	double g(colour.g);
	double b(colour.b);
	double a(colour.a);

	if ((!g && !b) || g == b) return colour;

	double lum_org = (g*g * G + b*b * B);
	double lum_swp = (b*b * G + g*g * B);
			
	double delta = sqrt(lum_org/lum_swp);
			
	double _b = g * delta;
			
	if (_b > 1)
	{
		g = sqrt((lum_org - B)/G);
		_b = 1;
	}
	else
	{
		g = b * delta;
	}
			
	return AColor(r, g, _b, a);
}

I didn’t want to use “if” since it is a little more expensive in MXS.
But in other lenguages I would have used it.

You can also simplify it to:

if (colour.g != colour.b) then ... else colour

	fn SwapBlueGreenChannels colour =
	(
		if (colour.g != colour.b) then
		(
			l1 = colour.g^2 * 5.0 + colour.b^2
			l2 = colour.b^2 * 5.0 + colour.g^2
			
			delta = sqrt (l1 / l2)
			
			b = colour.g * delta
			
			if b > 255 then
			(
				g = sqrt ((l1 - 65025)/5.0)
				b = 255
			)else(
				g = colour.b * delta
			)
			return (color colour.r g b)
		)else(
			return colour
		)
	)