Gray cards : the 12% - 18% controversy

Started Apr 13, 2013 | Questions thread
xpatUSA
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Re: The lovely Melissa RGB
In reply to cquarksnow, Apr 29, 2013

cquarksnow wrote:

Hi, xpatUSA -

As the gamma for this Melissa RGB (a.k.a. B@stard RGB) is not 2.2 , do you think the MelissaRGBD65.icc profile in Sandy McGuffog's site is nevertheless correct
https://sites.google.com/site/chromasoft/icmprofiles

based on his explanation :

The MelissaRGB profile deserves some explanation. Melissa RGB is not an "official" color space, but is the combination of the ProPhoto color space, with an sRGB gamma curve. It's important because Melissa RGB is what Lightroom uses for its readouts. Specifically, the RGB values you get as Lightroom readouts are in this space. Note that the Melissa RGB profile I'm providing here has the real sRGB gamma curve. The sRGB gamma is close to a 2.2 gamma, but is linear at low values. So, if you take a readout of the darkest patch of the GretagMacBeth chart, there is is about a 1.5% difference between the reading using ProPhoto at a 2.2 gamma and a true Melissa RGB profile.

Thanks,

Chris

Pardon my tardy reply, Chris,

I spent much of my time yesterday being slapped around in a color management forum on another site quite badly - to the extent that the Mod. deleted the entire thread. So it is with regret that I'll refrain from passing an opinion, in case my worthy opponent has followed me here.

I did visit Sandy McGuffog's site and found it interesting enough to download the profiles for further study. Thank you very much for the link.

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Regards,
Ted http://kronometric.org
SD9, SD10, EF-500, GH1.

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