[HDRI] Re: hdrgen's response curve file

[Gregory J. Ward]

Hi Lars,

Sorry for the poor response to your previous question.  I was a bit  
confused by it.  This is clearer:

> I understood the graphs / curves that I see response dependant on
> luminance? If I draw the curve as a graph, and I write "response"  
> to the
> y-axis, what is the label for the x-axis in this case?

In fact, the response curve is reversed.  The independent axis (x) is  
"sensor output" scaled from the 0-255 in the image to a 0-1 range for  
the recorded polynomial.  The dependent axis (y) produced by the  
polynomial should be proportional to luminance, but it needs to be  
multiplied by the appropriate scale factors taken from the ISO,  
speed, aperture, and calibration.

I hope this makes better sense.

-Greg