David Bannon Computer pictures can be divided into two broad groups, drawings and bitmaps. Generally people use the term drawings along with vector images, usually associated with programmes like Corel Draw, MacDraw etc. Drawing files contain information like a straight line between one spot an another or a red filled rectangle . To edit a drawing you alter one of the objects. From a user s point of view, it can be thought of as just a list of each and every dot in the image.
Bitmaps don t scale well.
Because they have a fixed number of dots in both the X and Y dimension, when you scale them the programme needs to make some guesses about how to fill in the gaps. You can, however, change any particular dot or group of dots with a suitable editor. There are a number of different bitmap formats, I am going to mention four , GIF, JPEG, TIFF and BMP and compare their use in our applications. Knowing which is best for a particular use will help you get the best results. Remember that you can translate a bitmap from one format to another, sometimes without any data loss.