Bitmap and Vector
The difference between bitmap and vector images seems pretty straightforward, and it really is. Bitmap are (usually) continuous tone images, made up of pixels. The term bitmap comes from the grid of bits that make up such an image in digital terms. Below is a continuous tone photo:
Looking very closely at the image, we can see the pixels. Each of these squares are represented by a number of bits. The grid formed by them is the bit map. Make sense?
Without getting into too much gory detail, the more pixels per inch, the higher quality image. Sort of. The web uses a standard of 72 pixels per inch. More on this here. Suffice to say that a bitmap is made up of a rectangular grid of little (usually) squares. Because of these squares, and how many of them you have in a given image, the image is considered high or low resolution. High is good, for printing and such. WEB IMAGES ARE LOW RESOLUTION. At 72 pixels per inch, they aren’t worth stealing.
Vector art, on the other hand, has no real resolution. It will look as sharp at a very small size as it will a very large size. It is resolution independent. It is resolution independent as a vector graphic. When you convert it for use on the web, it all the sudden becomes a bitmap. Interesting.
A vector image is typified by areas of flat color. Here is an example:
Here is an enlargement/detail of the same image:
Unless you can actually see it as a vector drawing (in this case in Adobe™ Illustrator), you really cannot get the effect. But what you can see in the images is the dithering in the upper image. Look closely at the bottom of the pot in the lower right hand corner. The spotted effect is dithering, or a use of optical blending to create more colors. Since there are not enough available colors in the palette being used, pixels of full colors that are available are mixed, much as a pointillist painting (Seurat?), and your eye/brain then mixes them, producing a tertiary color. This is direct, empirical, visual evidence of a vector image becoming a bitmap.
There is some true vector floating around the web. Flash uses it in a lot of cases, and Adobe has the SVG format, which is pretty cool, but hasn’t really caught on. Be careful with the examples and Safari, they crashed Safari hard (and Camino…), but Firefox seems OK on Mac. Support is gaining however, and apparently lots of mobile phones use SVG as their basic graphic format.
