Image Enhancement can be divided to Two class, the point processing and the histogram processing.
Six methods are used here, they are:
Po
- Image Negative
It's the simplest method to transform image using point processing - Thresholding Transformations
set a threshold function - Logarithmic Transformations
do the Log transformation to the image
which can widen the image grey level - Powers-Law Transformations
Also be called the famous Gamma transformation - Piecewise Linear Transformation Functions
The enhanced edition of Thresholding Transformations
Use histogram to process image.
The most used method is called histogram equalization