Understanding digital graphics...

A vector image commonly known as an ESP, AI, Fla is when a image is able to be blown up and not lose the quality of the picture.
A raster image however, the more you zoom in, the more the image gets distorted and pixel-lated. You have to compress the image to stop it from getting blurry. In order to maintain the image quality, you need to save it to Bitmap or BMP, other files you could use would be jpg, tiff, psd or gif.
Pixels are when an image is blown up and the image distorts into little squares that can be easily seen. The pixels are represented by different colour compounds such as:- RGB or CMYK, which is, Red, Green and Blue or Cyan, Magenta, Yellow and Black. The black has to be labelled K because B stands for blue already.
You can capture images on the computer by scanning them on a scanner, but when scanning the picture, the quality wont be good, ‘cause little dots will appear on the image and it will be no good to use then, unless, you turn the picture diagonally, the dots may not be on there.
Other ways of capturing pictures is by camera, and uploading them via the computer, this is a good way to do so, ‘cause they are your own picture so no little dots will be on, like watermarks.
The internet has images on too, but they are owned by other people that might not allow you use them for copyright purposes, in fact, you’d have to pay the owner to let you use them, which is a waste, when you can take your own pictures for free.
Photoshop and Flash are good examples where you can edit images. You can use vector based shapes to draw with, but can you can also edit pixels too, the format for Flash is SWF. This is vector based and can be used so the image doesn’t lose its quality.
Photoshop however uses raster based shapes to draw with, and images. The format the images are saved in is PSD.