Let's take a moment to talk about image size. Here is an image defined over a two-dimensional space. Since it is a finite image, it must have certain bounds. Let's say the limits along the x-axis are ten and 330. And similarly, along the y-axis, 20 to 278. Can you tell me what is the width and height of the image? How about the area that it occupies? Type in your answers in the boxes provided. 

That's right. The width is the difference between the two x-axis limits, 330 minus 10 equals 320. Similarly, the height is 258. And the area is simply width times height. And that comes out to 82,560. For digital images, the height is the same as the number of rows. And width is the number of columns. Thus, the area is the total number of picture elements or pixels. Now, if each pixel has three color values for red, green and blue, a color image, specifically an RGB image, has three different values at each pixel. This means a color image of this size has 82,560 times 3 total color values. If each color value is represented by one byte, then you need as many bytes to represent the entire color image. This should give you a sense of how much memory you need to store an image on a computer and how it depends on the width, height and number of color channels.