by Meysam                

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The main part of this question comes down to How to calculate Lux from EV?, leaving only the problem of estimating the overexposure or underexposure. It seems that you want to do at automatically. That's easy to answer: you can't, really, unless all of your images are of similar, known subjects. Otherwise, you would need a great deal of artificial ...


The good part is that the camera does measure brightness of the seen in terms of an EV value. There are several different ways to do the measurement. Most of the modes calculate the result from a weighted average of the image. Some put more emphasis in the middle part (spot metering for example). If you know what mode was used and how the weights are ...


You can't get any light information from the jpeg, the mapping is highly non trivial and depends on the RAW processing algorithm. No two pictures will use the same curve. You could get light information from the RAW file, however. However you need the actual recorded values, you can't pass the file through a RAW processor, you need to parse the RAW file ...

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