[argyllcms] Re: Feature request (and an implied question)

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 27 Jul 2010 15:13:04 +1000

Ben Goren wrote:
Hmmm...as I understand it, for any given illumination level and ISO, there is 
one corresponding EV (and vice-versa).

Right, but the information flow is from left to right :- you input the light
level, combine with other assumptions (ISO, intended exposure == object of
interests placement in resulting tonal curve + whether incident or reflected 
light is
being measured) and compute an EV. The fact that by making certain assumptions
you can backtrack and estimate the light levels from an EV, doesn't make them
safe equivalents (ie. to put it scientifically, they have different units).

So to add a correct EV output to spotread would entail adding options
to input the other parameters. At the moment, I feel this goes a bit beyond
it's intended use, given the command line tool constraints. It would
make more sense in a GUI tool context, where the assumptions can be

Graeme Gill.

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