18% gray card color code in photoshop

[alireza852019]

Hi

Anybody knows the exact color code of 18% gray card in professional photography (which is used in custom white balance)?

So please give me that color code in photoshop (in HSB).

Thanks.

[c.pfaffenbichler]

You forgot to mention which RGB Space you are talking about.

Edit: HSB is not like Lab or some other device independent color space.

HSL and HSV - Wikipedia

And have you done a web search?

Middle gray - Wikipedia

[D Fosse · Accepted solution]

Only applicable for Lab, not RGB or HSB - which is not a color space, but a generic color model, derived from RGB. You'd get very different numbers in sRGB, Adobe RGB and ProPhoto - and so you'd also get different HSB numbers.

In any case, the traditional 18% card isn't used much now. The standard tool today is the ColorChecker, which has standardized Lab numbers. These can be translated into sRGB/Adobe RGB/ProPhoto. This file is sRGB, just convert and read out in Photoshop to find numbers for other color spaces:

[G_Hoffmann]

A gray card doesn't have the color gray (might be surprising).

Gray card - Wikipedia

It has a reflectance spectrum which is flat in the region of visible light

and the reflectance factor is 18%.

The reflected light has the spectral distribution and therefore the color

temperatur of the illuminating light. Thus illuminant D50 reflects D50

and illuminant D65 reflects D65. That's "neutral".

Then, the color under D50 in Lab is 50,0,0 and the color under D65 in

sRGB is 119,119,119.

Both grays appear as equal, if the observer is adapted to the respective

illumination.

The short answer: the color in sRGB is 119,119,119

Best regards --Gernot Hoffmann

[D Fosse]

Yes, of course: it is applicable for RGB, as long as the RGB space is specified. Clumsy phrasing on my part above.

But "HSB" doesn't exist except as a derivative of an RGB space, which has to be defined.