Gray cards : the 12% - 18% controversy

Started Apr 13, 2013 | Questions thread
Roland Karlsson
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Re: The grey card is a reference for print making
In reply to xpatUSA, Apr 19, 2013

xpatUSA wrote:

OK, to keep things nice and simple and to avoid all these question marks in our discussion, let us take the example of a X3F file for a Sigma SD10 shot of a Kodak 18% gray card shot under D50 LED floodlighting with the metering showing 0 EV. Hopefully that is specific enough. If the spctral emission card is played, I also have halogens or an EF-500 flash. Take your pick. Next, we will extract the medium-size preview image from the X3F file. That way, no particular converter will be used and no post-processing will be done. The image will be exactly as God, er, sorry, Sigma created. We will open that JPEG image in ImageJ and we will immediately regard the ImageJ histogram.

Yes, this is very specific  Thanx!

Where will the peak value of the distribution lie? You tell me, and then I'll do the test.

Does it matter?

I mean, who is trying to get an image, from RAW, with the same look as the embedded JPEG?

But, lets assume it does matter, and that someone really wants to mimick the thumbnail in the real photo. Then, you can read all the different discussions on the topic and do whatever they tell you

I don't really care. Thats not how I work.

Neither do I, but elsewhere I've read that LR working space is named after a lady engineer at Adobe. The space is ProPhoto but the illuminant is D65 and the gamma is specifically sRGB, not 1/2.2.

courtesy of Wikipedia

Sorry - clumsy of me. Yes, it was sRGB "gamma". I keep forgetting that it is not 2.2, but rather linear for low values plus 2.4 for the rest.

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