Adjusting image intensity values

Question

I came to the imadjust function in MATLAB. It seems that this function enhances the contrast of the image. But, what is the theoretical basis for this function? In other words, if I say that this function as mentioned in the documentation adjusts the image intensity values, what does this exactly mean? What is it doing to the intensity values?

Thanks.

Answer 1

The formula for each pixel is likely to be

J = ((((I - low_in) / (high_in - low_in)) ^ gamma) * (high_out - low_out)) + low_out

If you leave off all the parameters, low_in and high_in are automatically selected so that the output contains 1% of its pixels at the highest and lowest values.