A Quick Intro to Graphics

Computerized images come in a variety of different formats. There are programs available that enable you to create interesting images on the computer. Painting programs offer virtual pencils and paintbrushes, as well as line drawing and text tools. Oth er programs make it possible to scan photographs, which converts them into digital information. Once they are converted, any combination of changes and manipulations can be made to enhance the quality or content of the image.

Graphics images can be line art, grayscale or color

number of bits...
Line art (bitmapped) images
Gray scale images
Color images

There are many different file types:

TIFF, PCX, PICT, EPS, BMP, GIF, JPEG, Pixelpaint, Macpaint, TARGA, X-Bitmap and X-Pixelmap

File types can vary as to how they are written

Compuserve GIF - 1 bit or 8 bit
- can only be 256 colors
- built in compression
GIF89
- transparent background
JPEG and PICT - 1 bit to 32 bit
- built in JPEG compression option
- compression only works with 16 to 32 bit
TIFF
- built in LZW compression option
- compression works with all types

These compression schemes help in transporting and storing images.

Resolution

measured in dots per inch
image size / image quality

Netscape and Mosaic can display GIF and JPEG

GIF files are easy to load
JPEG brings file size down when large numbers of images are used

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Last revision July 11, 1995