[argyllcms] Re: Which color instrument just for monitor?

  • From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 10 Nov 2009 15:11:28 -0700

On 2009 Nov 10, at 3:02 PM, Denis S wrote:

> Can you please tell more about ways of measuring ambient lighting using
> camera?

I've never tried it, but it should be very easy (at least, in principle) with 
anything that shoots RAW.

Get yourself a $10 Kodak gray card. Put it wherever you would a print. Meter 
the card for a standard exposure, be sure you've got the camera set to RAW, and 
take a picture. Focus isn't important; if anything, having the card *OUT* of 
focus is preferred.

Look up the exposure in an exposure value (EV) chart; there're bazillions on 
the 'Net if you don't already have one. That tells you the light level. If your 
EV chart doesn't have a conversion to whatever unit you want, Google again is 
your friend.

Open the picture in your favorite RAW processing software, and use the gray 
card to determine the color temperature.

That's about all there is to it....



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