If the image gray level of a pixel is represented by one byte, how many shades of gray can be represented?

A pixel represented by one byte can contain a total of 256 unique values. This is derived from the fact that a byte consists of 8 bits, and each bit can either be a 0 or a 1. The number of different combinations that can be formed using 8 bits is calculated as 2 raised to the power of the number of bits, which in this case is 2^8.

Calculating 2^8 gives:

2^8 = 256

Therefore, with each of those 256 values corresponding to a different shade of gray, one byte can indeed represent 256 distinct shades ranging from black to white as grayscale images are typically structured such that 0 corresponds to black and 255 corresponds to white (with various shades of gray in between). This makes the correct answer 256 shades of gray.