Bitmapped Graphics

What are bitmap graphics?

When you take a photograph using a digital camera or scan an image from a magazine, you are creating a bitmap graphic.

A bitmap graphic is composed of many tiny parts, called pixels, which are often many different colours. It is possible to edit each individual pixel.

Since the computer has to store information about every single pixel in the image, the file size of a bitmap graphic is often quite large.

When you resize a bitmap graphic, it tends to lose quality.

Bitmap files are especially suited for the storage of real-world images; complex images can be rasterized in conjunction with video, scanning, and photographic equipment and stored in a bitmap format.

Advantages of bitmap:

Bitmap files may be easily created from existing pixel data stored in an array in memory.

Retrieving pixel data stored in a bitmap file may often be accomplished by using a set of coordinates that allows the data to be conceptualized as a grid.

Pixel values may be modified individually or as large groups by altering a palette if present.

Bitmap files may translate well to dot-format output devices such as CRTs and printers.

Bitmap drawbacks:

They can be very large, particularly if the image contains a large number of colors. Data compression can shrink the size of pixel data, but the data must be expanded before it can be used, and this can slow down the reading and rendering process considerably. 

Also, the more complex a bitmap image (large number of colors and minute detail), the less efficient the compression process will be.

They typically do not scale very well. Shrinking an image by decimation (throwing away pixels) can change the image in an unacceptable manner, as can expanding the image through pixel replication. Because of this, bitmap files must usually be printed at the resolution in which they were originally stored.

Bitmap graphics software

Bitmap graphics can be created and edited using packages such as:

• Microsoft Paint
  Adobe Photoshop