Brighten RGB color? [solved]

Newbie & Debugging Questions
#1

I thought I’d be able to find an answer to this, but it’s turned out to be harder than I thought.

In MS paint, there’s a color editor tool that lets you brighten colors

My question is, what is the math behind that color brightening tool, rgb wise?

I thought that if I took a color, and converted the brightness in the “HSB” color model presented by the Color class, I would get an identical effect. However, this isn’t quite what I was looking for. For example, it’s impossible for me to brighten purple all the way up to white. It merely becomes a very bright purple. Using the Color class “brighten” and “darken” methods produce the same result.

So, simply put, how, numerically, can I implement a method that brightens or darkens a color by an amount that produces an effect identical to that in the picture?

Thanks

#2

The problem here is that HSB is easy to confuse with HSV

Found this on wikipedia. Hopefully it helps show the difference.

600×600 101 KB

#3

Ahhh, I thought HSB was the same as HSL, but it is actually the same as HSV. So that makes more sense. If anyone knows of a way to convert from HSB to HSL, I’d be appreciate it.

#4

I’ll try to find something else, but here’s the Wikipedia article if it helps.

EDIT: Here we go
EDIT 2: And this

#5

That first article was very good! Using it, I made my own class that can brighten colors in the way I wanted.

I will post it here in case someone else in the future is trying to do the same thing.

I tested it and it works :slight_smile:

import java.awt.Color;

public class ColorOperator {
	
	//colorInt should be a standard rgb hex value, like 0xffffff
	//light  should be a number from 0 to 255, 0 being black, 255 being white
	//returns a hex rgb int at the appropriate brightness level
	public static int setColorBrightness(int colorInt, int light){
		int r = ( colorInt >> 16 ) & 0xff;
		int g = ( colorInt >> 8 ) & 0xff;
		int b = ( colorInt ) & 0xff;

		float[] hsb = Color.RGBtoHSB(r, g, b, null);
		float[] hsl = HSBtoHSL(hsb);
		hsl[2] = light / 255f;
		hsb = HSLtoHSB(hsl);
				
		return Color.HSBtoRGB(hsb[0], hsb[1], hsb[2]) & 0xffffff;
	}
	
	public static float[] HSBtoHSL(float[] hsb){
		float[] hsl = new float[3];
		
		float l = (2 - hsb[1]) * hsb[2] / 2;
		float d = (l < .5f ? l * 2 : 2f - l * 2);
		
		hsl[0] = hsb[0];
		hsl[1] = d == 0 ? 0 : hsb[1] * hsb[2] / d;
		hsl[2] = l;
		
		return hsl;
	}
	
	public static float[] HSLtoHSB(float[] hsl){
		float[] hsb = new float[3];
		
		float b = hsl[2] + hsl[1] * (hsl[2] < .5f ? hsl[2] * 2 : 2 - hsl[2] * 2) / 2;
		
		hsb[0] = hsl[0];
		hsb[1] = b == 0 ? 0 : 2 * (1 - hsl[2] / b);
		hsb[2] = b;
		
		return hsb;
	}

}