**7. The histogram of equal-area division quantization method in watermarking**

The quantization levels are calculated using a method dependent on the image content, and then round off the value of pixels to the nearest quantization level. Using this method, the number of values transmitted over the channel is minimized. HEAD is a quantization method in which the transmitted values are reduced by mapping the values of image pixels to a finite number of quantization levels.

Process of HEAD quantization [11]:

