# response curve data from Photosphere

Hello everybody!

I'm a Fulbright student working on my second Master's in AE Lighting at UNL,
Omaha. My current research is on High Dynamic Range Imaging in Lighting.
Does anybody know how to get the information on the response curve from
Photosphere similar to the one that WebHDR would give you?

Thank you,
Yulia

···

--
Thank you,
*Yulia Tyukhova*
*
*
Fulbright Scholar,
Architectural Engineering Graduate Student, UNL-Omaha, NE, USA
B.S. and M.S. in Lighting Engineering (MPEI), Moscow, Russia
jtyukhova@yahoo.com
ytyukhova@unomaha.edu
+1 (402) 996 0910
PKI 247

Hi Yulia,

The camera response functions are stored in the text file \$HOME/Library/Preferences/Photosphere

Towards the end, you will see a list of camera responses that have been stored by make, model, and version. Each line looks something like this:

"NIKON CORPORATION"|"NIKON D200"|"Ver.2.01"|{-4.765716e-04,1.355876e-01,-1.269868e-01,9.918758e-01}|{-6.390453e-04,1.371893e-01,-1.224765e-01,9.859263e-01}|{-9.074065e-04,1.351222e-01,-1.165654e-01,9.823506e-01}

The coefficients enclosed in curly braces are the polynomial camera responses, one per color in red, green, and blue order. The coefficient order is from low to high power, so the above line translates to:

red(r) = -4.765716e-04 + 1.355876e-01*r + -1.269868e-01*r^2 + 9.918758e-01*r^3;

green(g) = -6.390453e-04 + 1.371893e-01*g + -1.224765e-01*g^2 + 9.859263e-01*g^3;

blue(b) = -9.074065e-04 + 1.351222e-01*b + -1.165654e-01*b^2 + 9.823506e-01*b^3

The input (r,g,b) values are camera sensor values normalized in a 0-1 range. The output values are related to world luminance units, sometimes with a calibration scaling factor built in.

I hope this is helpful.

-Greg

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From: "Tyukhova, Yulia" <ytyukhova@unomaha.edu>
Date: October 25, 2011 3:00:13 PM PDT

Hello everybody!

I'm a Fulbright student working on my second Master's in AE Lighting at UNL, Omaha. My current research is on High Dynamic Range Imaging in Lighting.
Does anybody know how to get the information on the response curve from Photosphere similar to the one that WebHDR would give you?

Thank you,
Yulia
--
Thank you,
Yulia Tyukhova