To illustrate the direct access to pixel values, we will create a simple function that adds salt-and-pepper noise to an image. As the name suggests, salt-and-pepper noise is a particular type of noise in which some randomly selected pixels are replaced by a white or a black pixel. This type of noise can occur in faulty communications when the value of some pixels is lost during the transmission. In our case, we will simply randomly select a few pixels and assign them a white color.

We create a function that receives an input image. This is the image that will be modified by our function. The second parameter is the number of pixels on which we want to overwrite white values:

void salt(cv::Mat...