Pixels:

Are "maps" of square picture elements that visually create the image. This image is a close up of the rear view mirror.

Resolution | dpi/ppi/lpi:

Dots per inch/pixels per inch/lines per inch. dpi is the number of dots (pixels) per inch within an image and is the standard format to measure computer graphical images. The more pixels there are per inch, the higher the resolution of the image will be. If this is changed proportionally with the size (e.g. increase size/decrease dpi) then there is no change in quality on the projected image. If this is changed independent of the size, then there is a change in quality. General rule of thumb, you can always decrease the image in size but you can’t increase the image without loosing quality.

• 72 dpi = screen resolution
• 300 dpi and higher = print resolution

Bitmap (Raster) Images

Bitmap (Raster) Images are made up of varying amounts of pixels and colors. The most common type of Bitmap images used for the Web today are JPEG and GIF.

• 1bit - 2 colors (black and white)
• 8 bit - grey scale or color (256 colors or shades of grey)
• 16 bit - RGB (thousands of colors)
• 24 bit - RGB (millions of colors)
• 32 bit - CMYK (millions of colors +)

Vector Images

Vector Images use paths to draw an image and are actually constructed of mathematical formulas.

• Can create very small file sizes because the image is not constructed of pixels
• Used for line art, logos, clip art, Flash files, etc.
• Good for animation on the Web (Flash)
• Scaleable