How can I get luminance from dslr?
I have been trying to obtain the image brightness in Opencv and to try get the luminance However, I feel dizzy Is it possible to obtain luminance from the pixel brigtness? Could you please help me with a method or algorithm, that can be realised through OpenCv Thanks in advance
Could you explain better? If you purely want the luminance channel, then it is a task of transforming the input image to the correct color space and then splitting the channels. What is the image given?
From the posted image, it seems that you want to measure the incident radiation (cd/m²). However the cameras can only measure the reflected radiation, which depend on a lot of factors: the incident light, the angles between surface, the light source and the observer and the reflection properties of the material (color, shinyness,...).
The relations between these factors are described by the Phong reflection model.
If you want the reflected luminance, you'll still have to take into account the exposure of the photo (shutter speed, f-number, sensitivity) and the post-processing (gamma, sharpness, contrast...) (this can be at least eliminated by decoding directly the raw data).