Once you managed to get photoelastic images of your sample you can either be happy about such a nice picture or you may want to go a bit farther and get something more quantitative. In this section we will present the different analysis you can carry out and what you could measure.
Simple image intensity analysis:
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At order zero, you can simply analyze the average image intensity. You assume that the brighter the larger the stress and with a rough calibration you can get pressure estimation. More details about how to do it are given [here]().
Image gradient analysis:
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A more sophisticated method consists in analyzing the intensity of the squared image intensity gradient $`G^2`$ which gives information about the photoelastic fringe density. It has been shown by [*et al.*]() that this is proportional to the inner pressure. Calibrating the method for your material you can get a quite accurate information about the pressure in you sample. More details about this method are given [here]().
