Since a digital image is sampled at discrete locations in space, it can be written down as a two-dimensional array or matrix of values. Here is an example. Note that this matrix has fractional values, both positive as well as negative. But what if we could only represent a small set of integer values, say between 0 and 5? How would you quantize this matrix so that the result consists of only the integers 0 through 5? Enter the converted values in the corresponding boxes. Assume that we always round down. For example, 1.8 becomes 1. Also, be careful about the limits. Anything less than the lower limit 0, should be converted to 0, and anything greater than the upper limit 5, should be converted to 5. 

To get the quantized matrix, convert each number, always rounding down. Integer values within the given range remain the same. Anything above the upper limit becomes 5. Similarly, anything that is less than 0, in this case -1.3 becomes 0, and so on. Note how quantization results in a loss of detail. Extreme values beyond the range are lost as well.