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Hello I have some confusions about extracting data from images and I know lots of image processing experts are in here. I would appreciate if someone can help me realize some concepts. how we can get some information,like intensity of a the light source from images? I know we can extract RGB value, but these values are associated with the surfaces and not with the light source spectra (I am talking about white light source with different spectra not monochromatic wavelength). is there a way to extract some information of the light source from images with matlab? should we convert color images to greyscale images? if yes, can you explain how grey scale giving us intensity (or other photometric data)? I know about HDRI so feel free to refer to them

Far
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  • To be able to get light intensity in terms of lux for instance would require knowledge of the aperture shutter speed etc. and would probably not lead to accurate analysis however you may be able to get relativistic intensity's by comparing the grey scale values. https://stackoverflow.com/questions/4876315/determining-image-luminance-brightness/4876528#4876528 – Alessi 42 Aug 28 '17 at 19:25

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You can in each language get the red (=r), green (=g), blue (=b) and alpha bytes of each pixel of an image. The internet give you many formulas to calculate the different possible values on base of the amount of red, green and blue.

For example this link provides how to calculate the hsv value with r, g and b.

It is more or less a question HOW (language, libraries) you want to do it.

Teneko
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