what is 18% grey in photoshop?

[mastertrinity]

hi, i have been experimenting with raw and heard that a grey card is used before taking the photo, i dont have a grey card however i plan to get one but when im in photoshop i wondered what the RGB values would be so that i can simply pick 18% grey via photoshop when changing white balance.

can anyone help?

 

[mart77]

you have to pick the 18% grey of the grey card the way the camera sees it, it may see it as 30% grey and you tell it that, that bit of grey in the pic is actually 18%.
Just finding 18% grey in photoshop and telling it that wont help, it already knows that.

 

[Kaouthia]

It doesn't matter if it's 18% grey or not for white balance. If it's supposed to be grey (any lightness), click it.

The 18% bit is for metering, as it's what cameras attempt to automatically shoot the scene at as an average.

 

[snappingsam]

A 18% grey card should be 117-119 in sRGB space....

On A MacBeth colorchecker the next brightest is 156 - the white 235 and the black 40

That will give you the perfect contrast and neutral