Adds and reads watermark on image
pip install opencv-python numpy PyWavelets
python ./embed.py --img x22.png --pwd 3465 --out x22w.png --wm a61d358eaff59724fdf5b3ce06447dc9
python ./unembed.py --img x22w.png --pwd 3465
python ./embed.py -h
python ./unembed.py -h