[Radiance-general] Radiance

[Guglielmetti, Robert]

I'm not sure what you mean by the "radiance scale factor". Are you trying to compute the cameras' response curves? As for your second question, you won't be able to calculate radiance from a single exposure, even if all the details about that exposure are known. The process you are describing requires a high dynamic range (HDR) image, which is comprised of multiple exposures. The typical minimum is three exposures separated by 2 f-stops each, but ideally the longest exposure should have zero black pixels and the shortest have no white pixels. This ideal is only necessary to capture scenes of extreme dynamic range, however.

Radiance-online.org also hosts an hdr mailing list which is definitely worth subscribing to:

http://www.radiance-online.org/mailman/listinfo/hdri

Robert Guglielmetti  IES, LEED AP
Building Energy Efficiency Engineer
National Renewable Energy Laboratory (NREL)
1617 Cole Blvd, MS-5202
Golden, CO 80401
robert.guglielmetti at nrel.gov
303.275.4319

From: radiance-general-bounces at radiance-online.org [mailto:radiance-general-bounces at radiance-online.org] On Behalf Of Brajesh Lal
Sent: Wednesday, July 01, 2009 7:55 AM
To: radiance-general at radiance-online.org
Subject: [Radiance-general] Radiance

Hi All,

I have taken images of same scene from two different camera at same time and same day. How to find the radiance scale factor between the two cameras.

I will be grateful if somebody can explain me mathematical relation to compute the radiance of a  point in the scene.
if the pixel value of the point  and cameras ISO value, F-stop, Shutter Speed are known


Best Regards,
Brajesh Lal


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