# Thread: what are the RGB values for an 18% gray?

1. ## what are the RGB values for an 18% gray?

Does anyone know what are the RGB values for 18% gray? Is it R:128, G:128, B:128?

thanx!!

2. ## Re: what are the RGB values for an 18% gray?

In RGB it's 128128128, but for reflectance it's 117.

3. ## Re: what are the RGB values for an 18% gray?

18% Gray = R:224 G:224 B:224

4. ## Re: what are the RGB values for an 18% gray?

Originally Posted by Enchanted
18% Gray = R:224 G:224 B:224
It's not linear.

(117 / 255)^2.2 = 0.18

5. ## Re: what are the RGB values for an 18% gray?

Originally Posted by grantyale
It's not linear.

(117 / 255)^2.2 = 0.18
In sRGB, it's closer to 118. sRGB doesn't use a simple power law and gamma=2.2 is only an approximation. To get a more accurate approximation, you can dither 64.46% pixels with a value of 118 and the remaining 35.54% with a value of 117.

6. ## Re: what are the RGB values for an 18% gray?

All the given advice is far too "chim". Is there a more simplified explanation that can be understood by all laypersons?

7. ## Re: what are the RGB values for an 18% gray?

The reason it gets complicated, is that there is no simple three-values answer. It depends on the color profile you're working in. The RGB values of a given color varies between different color spaces (profiles).

8. ## Re: what are the RGB values for an 18% gray?

A lot of replies! Thanks every one for your input!

9. ## Re: what are the RGB values for an 18% gray?

RGB does not describe absolute colour... it is relative to the profile of your monitor, and to the profile of the image...

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