What is black/white relative exposure?

Software darktable
1

Hi, I’m a Japanese translator of darktable who doesn’t know how to translate “black/white relative exposure” of filmicrgb.
My current translation literally means "relative exposure value of black/white ", that is, black’s/white’s exposure value which is measured relative to middle grey. Do I understand it correctly? Or does it mean “exposure which is measured relative to black/white”?
Thank you so much for your help.

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Shinozaki-san,

I believe your understanding is correct – those relative exposure sliders have an EV value that is relative to middle grey. The white relative exposure indicates how many stops above middle grey an area of the image should be for it to be treated as pure white by the display, and the black relative exposure indicates how many stops below middle grey an area should be in order that it should be treated as pure black by the display.

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Arigato gozaimasu Maguire-san

I saw some beautiful photos taken in Japan on your Flickr :grinning:

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I enjoyed my time in Japan very much. I bought a camera while I was there, and I learned a little about photography while trying to work out how to use it :slight_smile: Now that I’m back in Australia, I need to get out with my camera and learn some more

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Konnichiwa @anon68675049,

I believe that the tool hints for those sliders explain the action quite well:

White relative exposure
Number of stops between middle gray and pure white.
This is a reading a light meter would give you on the scene.
Adjust so highlights clipping is avoided.

Black relative exposure
Number of stops between middle gray and pure black.
This is a reading a light meter would give you on the scene.
Increase to get more contrast.
Decrease to recover more details in low-lights.

Have fun!
Claes in Lund, Sweden

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Konnichiwa Claes,

thanks for the reply. Yeah I actually have checked the tooltip, the user manual, and posts from Aurélien Pierre in this forum and youtube, so I suppose that I understand what the sliders do. But I wanted to know what the ambiguous names exactly mean, because the literal Japanese translation is too vague and not a common expression.

I found that the french translation (“exposition relative du noir/blanc”) is helpful.