How to get OverExposure , under exposure, and normal Picture using Matlab code

if i am given a picture and want to have its OverExposure , under exposure, and normal forms , is this possible using matlab code ? please refer me some links i am new to matlab

Answer 1

[Image Analyst]

Just add or subtract some number from them.

overExposedImage = grayImage + 50;
underExposedImage = grayImage - 75;

[Image Analyst]

http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

[Deepti Ghadiyaram]

The link does not have anything related to the above question.. Also, the above operation would result in a global shift of the intensity values. Is there a way to locally introduce exposure distortions?

[Image Analyst]

I don't know why the link is there. It was probably in response to a question that they have since deleted.

Distortion is a spatial optical aberration, not an intensity problem.

To change the exposure locally on a pixel-by-pixel basis, you can multiply or divide, or add or subtract some amount from the original gray level, where the amount changes on a pixel-by-pixel local basis.