There are many different ways to represent the same digital picture. These are called "formats". Some formats contain all the visual information of a picture, every pixel. Some use tricks to save on file size by not including every pixel. We say these formats are "compressed". They are compressed in the sense that they have smaller file sizes but look about the same when viewed. For web pages, almost all the pictures you see are either JPEG (jpg) or GIF. Both of these formats compress the file size substantially from the full pixel by pixel representation. In the Windows computers, the full representation is called a bitmap (bmp). Let's try another experiment to see how much smaller the compressed files are.

To do this we must start the program called Paint. Go to Start --> Programs --> Accessories. Paint is a free program that allows you to create and edit images that are made of pixels. For our experiment, set the size of the Paint image to 400 by 300 pixels. Use the Image menu and choose Attributes. Then fill in the 400 for width and 300 for height. There is nothing special about these numbers. The image can have any width and height.

Now, create a simple picture on the screen. Use the tools along the left side of the screen. Make a scribble with the paint tool. Then use the Paint Bucket tool and fill each section of the scribble with colors. Here is what that may look like: