A simple tool for enhancement the photos of documents, notes, books, etc.
It makes lighting uniform and increases the contrast of the images.
python3 enhance.py img.jpg -o output.jpg --gray --sigma 50 --thrs 0.7 0.95
--gray makes grayscale image,
--sigma SIGMA is the parameter for Gaussian filter (required for uniform lighting),
--thrs LOW HIGH are two thresholds for contrast stretching,
--format FMT is the format of output image.
