Data Compression


Criteria

Survey Formats

Basics

Compression Methods

Data Formats

Files

Audio Data

Image Data

GIF

Colours

Data Compression

Characteristics

GIF87a

GIF89a

Patents

Optimizations

Examples

Drawings

JPEG

Video Data


Glossary

Index


Download


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GIF - Characteristics


The characteristics of GIF result on the one hand from the limited number of colours and on the other hand from the lossless compression. This distinguishes GIF from JPEG, the other important internet format. In reversal conclusion, JPEG is able to process arbitrary colours, but applies a lossy compression.


GIF does not provide losses of picture information, if the colour representation does not exceed its limitation. If a colour reduction would become necessary, the quality losses may be significant.


Suitable areas of application:


  • Drawings (technical or line-drawings)
  • Diagrams
  • Sketches
  • Logos
  • Icons
  • Thumbnails

Restricted areas of application:

  • Photos, photo-realistic graphics
  • Files, which require a strong compression and/or reduction of the data volume
  • Generally data with a large number of colours
  • Pictures with homogenous colour changes
  • Open source or freeware projects (licenses are required; it is not well-known, when patents expire in ALL countries)

Apart from the characteristics resulting from representable contents, GIF is characterised by a relatively simple implementation. The necessary resources are derived from the technical conditions of the 80's and require only minimum storage capacity, computer and graphics performance.


In order to get a visible result in spite of very low transfer rates, an interlaced mode is available starting with every eighth line. The remaining lines are added in later phases according to a certain scheme. Instead the common progressive mode processes the contents line by line.


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GIF - Graphic Interchange Format GIF - Data Compression GIF87a