查找颜色范围

Question

I want to find a range of colours from the value of one RGB value

If I was given rgb(0,100,200) for example it would give me everything between rgb(0,0,255) and rgb(0,255,255). However not rgb(255,0,255).

Similarly rgb(150,50,0). Return: rgb(255,0,0) and rgb(255,255,0). Not rgb(255,0,255).

Making sense?

Im using PHP

Answer 1

The algorithm you explain is basically: "A color consists of two RGB components. Let the strongest RGB component be S and the other component O. Create 255 variations where you let S be (255) and O ranges from 0 to 255."

E.g. all of the below example yield the same result:

a) rgb(0,100,200) 
b) rgb(0,199,200)
c) rgb(0,254,255)
d) rgb(0,1,2)

Result: rgb(0,[0-255],255)

This means you only have a 6 variations.

1. Red is the largest component, Green next largest => rgb(255,[0-255],0)
2. Red is the largest component, Blue next largest => rgb(255,0,[0-255])
3. Green is the largest component, Red next largest => rgb([0-255],255,0)
4. Green is the largest component, Blue next largest => rgb([0-255],0,255)
5. Blue is the largest component, Red next largest => rgb([0-255],0,255)
6. Blue is the largest component, Green next largest => rgb(0,[0-255],255)

The intention of your algorithm is not clear, so I am guessing your use case is actually different from what you explain. It does not handle colors with either 1 or 3 components (most colors actually).

If your goal is to find similar colors (e.g. a color in a certain distance) there are better approaches. For example you could convert your colors to a HSV color space (Hue, Saturation, Value) and then say that the color is similar if the either of the components H, S or V are +/- 10 steps from your original.

E.g.:

rgb(255,100,0) => hsv(24,100,100)

Your range is then hsv([14-34],[90-110],[90-110])