How to determine the brightness%?

Question

According to http://www.workwithcolor.com/color-luminance-2233.htm , RED (# FF0000) has a brightness: 54%. and light pink (# FF8080) has a brightness: 89%. Our designers love it, but how is it defined? Try it here: http://www.workwithcolor.com/hsl-color-schemer-01.htm

I tried to use the relative brightness formula published by the W3C , and although the range is [0.1], red is 0.21 and white is 1.00 .

I think maybe what color work makes the first hidden color in shades of gray and reads the brightness of gray. I tried, but it still does not give the same result.

I have tried so far: http://jsfiddle.net/HytZQ/

Answer 1

Check the formula here: Formula for determining RGB color brightness

 Luminance (standard, objective): (0.2126*R) + (0.7152*G) + (0.0722*B) 

Put R = 255 and G = B = 0, you get 54

Edit: For relative brightness, divide by maximum (255) you get 21%

For white you get 100%

Answer 2

Brightness, Luminosity and Brightness are not the same thing. The HSL color model would be useful if one of the components were L (luminosity).

Brightness is not something you need to take care of according to your requirement. read the discussion link:

http://www.cambridgeincolour.com/forums/thread23366.htm

RED (# FF0000) has a brightness of 50% at 100% saturation, but the software programs we use slightly adjust the values ​​to take into account perceptual factors.

You need to start with pure colors. Pure colors are colors in the HSL color space that have a brightness of 50% and a saturation of 100%, and changing the hue value gives you pure colors. In total, 6 * 60 colors are available, available through HSL / RGB color spaces. those. if you summarize the colors generated using the combinations below, you get 360 pure colors.

R = 255 * (x / 60), G = 0, B = 255; where x varies from 0 to 60 R = 255 * (x / 60), G = 255, B = 0; where x varies from 0 to 60

R = 255, G = 255 * (x / 60), B = 0; where x varies from 0 to 60 R = 0, G = 255 * (x / 60), B = 255; where x varies from 0 to 60

R = 255, G = 0, B = 255 * (x / 60); where x varies from 0 to 60 R = 0, G = 255, B = 255 * (x / 60); where x varies from 0 to 60

leave all the colors that we see, manipulate the saturation and brightness.

Now, to get grayscale images:

1 - You can use the brightness formula proposed by Jerry (there are other formulas to improve performance). 2 - You can change the saturation to 0% in the HSL color space, which corresponds to http://www.workwithcolor.com/hsl-color-schemer-01.htm .