In digital systems, an image is represented as a rectangular matrix or a grid of square pixels. An image that is $1920$ pixels wide and $1080$ pixels long has a total of $1920\backslash$times $1080=2,073,600$ pixels or around $2$ megapixels. Each pixel holds a numeric value. Depending on the pixel format used, the numeric value stored in a pixel is interpreted differently. For example, if the pixel format is binary, each pixel corresponds to black or white. If the pixel format is grayscale, each pixel carries light$-$intensity information. The most common pixel format is the $24-$bit full$-$color format with $8$ bits $($values $0255)$ for each color channel $($red$,$ green, and blue$).$ A $1920\backslash$times $1080$ image in this format uses about $6$ MBs in memory $($assuming no compression$).$ This exercise uses an $8-$bit grayscale format where pixel values lie between $0$ and $255.$ Below, you can see a portrait of Abraham Lincoln as a $16$x$12$ grayscale image and corresponding $2$D array holding the numeric values of $192$ pixels.