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Summary: File formats

Uses for GIF and JPEG Files

Netscape Navigator, Microsoft Internet Explorer, and most other browsers support both GIF and JPEG graphics (as of this writing, PNG graphics are not adequately supported). In theory, you could use either graphic format for the visual elements of your Web pages. In practice, however, most Web developers will continue to favor the GIF format for most page design elements, diagrams, and images that must not dither on 8-bit display screens. Designers choose the JPEG format mostly for photographs, complex "photographic" illustrations, medical images, and other types of images in which the compression artifacts of the JPEG process do not severely compromise image quality.

[画像:Illustration: Examples of best uses for the GIF format]

Advantages of GIF files

GIF is the most widely supported graphics format on the Web
GIFs of diagrammatic images look better than JPEGs
GIF supports transparency and interlacing

[画像:Illustration: Examples of best uses for the JPEG format]

Advantages of JPEG images

Huge compression ratios mean faster download speeds
JPEG produces excellent results for most photographs and complex images
JPEG supports full-color (24-bit, "true color") images

GRAPHICS
Characteristics
• Color displays
• "Browser-safe" colors
• Dithering
• Screen resolution
• Gamma
• Graphics & bandwidth
Graphic file formats
• GIF files
• JPEG graphics
• PNG graphics
• Imaging strategies
• Summary: File formats
Images on the screen
• Screen versus print
• Complex illustrations
• Diagrams
HTML & graphics
Accessibility
References

MULTIMEDIA

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Last updated 5 March 2004

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