Data Compression


Criteria

Survey Formats

Basics

Compression Methods

Data Formats

Files

Audio Data

Image Data

GIF

Colours

Data Compression

Characteristics

GIF87a

GIF89a

Patents

Optimizations

Colour Tables

Optimized Tables

Standard Tables

Raster

Anti-Aliasing

Examples

Drawings

JPEG

Video Data


Glossary

Index


Download


www.BinaryEssence.com

GIF - Optimized Colour Tables


GIF offers the opportunity to use individual colour tables, so the question arises how this may be utilised. Most applications for picture processing provide functions to generate those tables. Afterwards they may be optimized manually or automatically.


Such routines try to determine which combination of colours is approximately the best. The most simple option is the selection of those colours appearing most frequently. However rarely used colours may disappear thereby, which are of great importance for the picture's contents like labels, legends or marks.


In such a case it is the best to reduce gradually the number of colours and to see, when unacceptable changes appear. If this border is exceeded, one needs to reactivate the last file. Additionally one has the possibility to adapt the colour allocation manually e.g. after unwanted changes.


 <   ^   > 

GIF - Optimizations GIF - Colour Tables GIF - Standard Colour Tables