What Photoshop fill for 18% grey card?

Started Dec 16, 2005 | Discussions thread
NAwlins Contrarian Veteran Member • Posts: 5,281
Inclusive reckoning explains it?
1

I measured the #23 patch (supposed to be the 18% gray)

It's close to 9% gray. You can use Y100 to read percents.

As pixelgenius notes in https://www.dpreview.com/forums/post/64158780 - 18% gray is close to L 50% in Lab.

that patch #23 is 18% gray!!!

I cannot find anywhere that X-rite states it is.

They do show this:

https://xritephoto.com/ph_product_overview.aspx?ID=820&Action=support&SupportID=5159

https://www.xrite.com/service-support/whereis18graycardoncolorcheckerpassport

That page says that "the 4th patch from the white one in the bottom row of the ColorChecker classic is 18% gray." Mostly today in the U.S., we don't use inclusive reckoning, and so we think that that must refer to patch 23. But using inclusive reckoning, the white patch is the first, so the fourth patch starting with white is patch 22, which is fairly close to 18% gray. I don't know what X-Rite intended / was trying to say. It's awkward / ambiguous phraseology regardless. X-Rite should say something like, 'With the neutrals as the bottom row, the fourth patch is close to 18% gray.'

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