R. Craig Collins > Intro to Computer Graphics > Bitmaps and TIFF

Bitmaps and TIFF © R. Craig Collins, 2007

Bitmaps and TIFF

Bitmaps are a type of raster image where the image is represented as a series of colored dots, or pixels. Each pixel is stored as a specific color, represented by a series of 1s and 0s. The default file type for Microsoft Paint is the 24 bit .bmp, which uses twenty-four 1s and 0s to represent up to 16.7 million shades.

The format is fairly low resolution; that is, a fairly low number of dots per inch (often between 70 and 90), so it is best suited for simple line drawings, charts, etc. As it is often such low resolution, many consider the quality too low for photographs, which often need to be crisp so they can be printed on high resolution printers.

The files tend to be quite large, as there is no attempt to compress the file. (optional information on color representation in web pages is available, compression will be covered in the next overview)

TIFF files, Tagged Image File Format files. While the format allows many other features, it is important typically because it can handle 24 bit or greater colors AND high resolution files. This makes it a popular option to store original scanned or digital camera images.

But, as with bmp, the files can often be quite large, to store the large number of colors and preserve the resolution. (Some tiff files can be compressed to an extent, but normally without changing the color depth. (optional information on color representation in web pages is available, compression will be covered in the next overview)

tiff is widely used for storing original photos; but neither .bmp or .tiff formats are used by most web browsers, due to the large file size and the inability of most monitors to display high resolution.

In the next overview, generating files that are web appropriate will be started, beginning with the format best suited of simple line drawings and charts... gif