Relationship - Outdoor illumination value, HDR pixel value, ISO, Shutter Speed and fstop


Two different cameras are used for taking the same scene at same time and same day. If we know the each camera ISO value, shutter Speed and f-stop value and the HDR pixel value of the images produced by them then what is the relationship between them with respect to captured outdoor scene radiance value or how one can compare the radiance value captured by both camera. I will appreciate if one can give some mathematical relationship or formula.

Best Regards, Brajesh Lal


what you want is a HDR image that contains pixel values in photometric
units. To achieve this generate a reasonable response curve, which
compensates for the non-linear response of the sensor to illuminance on
each channel. Second, you should compare the luminance from the pixels
to a reference. One way to do so is using a stabilized light source.
This will give you a factor that can be used as a multiplier to get from
the pixel values to cd/m2.

Besides that, aperture size, focus distance, the lens etc. all have
influence on the pixel values in your image...

Cheers, Lars.