tyotw / rgb2lab-rgb2hsl

convert a single or multi colors between rgb and Lab or rgb and hsl.

Color Space Conversion

It can convert rgb to lab, lab to rgb, rgb to hsl and hsl to rgb.

RGB：0...255

LAB：

​ L：Lightness 0...100

​ A: -128...127

​ B: -128...127

HSL:

​ h(float): hue 0...1

​ s(float): Saturation 0...1 (0=toward grey, 1=pure color)

​ l(float): Lightness 0...1 (0=black 0.5=pure color 1=white)

As we often need to convert the whole image colors, I also add matrix calculation so the speed could be very fast when we need to convert a lot of colors at once.

rgb2lab,lab2rgb

Single color conversion

import LAB
rgb=[123,245,211]
lab=LAB.rgb2lab(rgb)
rgb=LAB.lab2rgb(lab)

Multi colors conversion

import LAB
import numpy as np
colors=np.random.randint(0,255,size=(900*600,3))
labs=LAB.rgb2lab_matrix(colors)
rgbs=LAB.lab2rgb_matrix(labs)

rgb2hsl,hsl2rgb

Single color conversion

import HSL
rgb=[123,245,211]
hsl=HSL.rgb2hsl(rgb)
rgb=HSL.hsl2rgb(hsl)

Multi colors conversion

import LAB
import numpy as np
colors=np.random.randint(0,255,size=(900*600,3))
hsls=LAB.rgb2hsl_matrix(colors)
rgbs=LAB.hsl2rgb_matrix(hsls)

Time comparison

For n is 600*900, the time table is as follows. We can see using matrix calculation is much faster and it saves a lot of time.

|   time   | single for n times | matrix |
| -------- |:------------------:|:------:|
| rgb2lab  |      5.923s        | 0.234s |
| lab2rgb  |      7.313s        | 0.235s |
|          |                    |        |
| rgb2hsl  |      4.782s        | 0.156s |
| hsl2rgb  |      3.249s        | 0.140s |