How to overexpose an image

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Hi,I have an image taken against a bright background via webcam.Now obviously the image is highly underexposed. I would like to know what algoithms I can apply that will help me to avoid underexposed image If it helps I have included two images the underexposed one and the same image with histogram equalisation applied on it. But I want to know what else can be done to improve the quality of the image. And I apologise for the vagueness and lack of specificity.

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