Bitmap vs Vector

Bitmap (or raster) images:

• are made up of pixel in a grid.
• what is pixel? a very small square that is assigned a color, and then arranged in a pattern to form the image. 
• when we zoom in on a bitmap image, we can see individual pixels that make up that image.
• resolution dependent. Resolution - refers to the number of pixels in an image and is usually stated as dpi (dot per inch) or ppi (pixel per inch)

Common bitmap formats include:
 
• BMP
• GIF
• JPEG, JPG
• PNG
• PCX
• TIFF
• PSD (Adobe Photoshop)

Popular bitmap editing programs are:
 
• Microsoft Paint
• Adobe Photoshop
• Corel Photo-Paint
• Corel Paint Shop Pro
• The GIMP

Key Points About Bitmap Images:
• pixels in a grid
• resolution dependent
• resizing reduces quality
• easily converted
• restricted to rectangle
• minimal support for transparency
  
Vector images:

• are not based on pixel patterns, but instead use mathematical formulas to draw lines and curves that can be combined to create an image from geometric objects such as circles and polygons
• can be manipulating the lines and curves that make up the image using a program such as Adobe Illustrator.
• resolution independent - because they can be output to the highest quality at any scale

Common vector formats:

• AI (Adobe Illustrator)
• CDR (CorelDRAW)
• CGM (Computer Graphics Metafile)
• SWF (Shockwave Flash)
• DXF (AutoCAD and other CAD software)

 
 Advantage of vector images:

• have much smaller size compare to bitmap (raster)
• A vector image just has to store the mathematical formulas that make up the image, which take up less space. 
• Vector images are also more scalable than bitmap images. When a vector image is scaled up, the image is redrawn using the mathematical formula. The resulting image is just as smooth as the original 

However, vector format are not well supported on the web. Currently, the only way vector images can be displayed on the Web is by requiring viewers to install a browser plug-in.

The two most popular image formats used on the Web, GIF and JPEG are bitmap formats. Most vector images must be converted into bitmap images (or rasterized) before they can be used on the web