Cisco Cisco IPICS Release 2.1 Licensing Information

 change.log        Version-to-version change highlights.

Programmer and internal documentation:

 libjpeg.doc       How to use the JPEG library in your own programs.

 example.c         Sample code for calling the JPEG library.

 structure.doc     Overview of the JPEG library's internal structure.

 filelist.doc      Road map of IJG files.

 coderules.doc     Coding style rules --- please read if you contribute code.

 

Please read at least the files install.doc and usage.doc.  Useful information

can also be found in the JPEG FAQ (Frequently Asked Questions) article.  See

ARCHIVE LOCATIONS below to find out where to obtain the FAQ article.

 

If you want to understand how the JPEG code works, we suggest reading one or

more of the REFERENCES, then looking at the documentation files (in roughly

the order listed) before diving into the code.

 

 

OVERVIEW

========

 

This package contains C software to implement JPEG image compression and

decompression.  JPEG (pronounced "jay-peg") is a standardized compression

method for full-color and gray-scale images.  JPEG is intended for compressing

"real-world" scenes; line drawings, cartoons and other non-realistic images

are not its strong suit.  JPEG is lossy, meaning that the output image is not

exactly identical to the input image.  Hence you must not use JPEG if you

have to have identical output bits.  However, on typical photographic images,

very good compression levels can be obtained with no visible change, and

remarkably high compression levels are possible if you can tolerate a

low-quality image.  For more details, see the references, or just experiment

with various compression settings.

 

This software implements JPEG baseline, extended-sequential, and progressive

compression processes.  Provision is made for supporting all variants of these

processes, although some uncommon parameter settings aren't implemented yet.

For legal reasons, we are not distributing code for the arithmetic-coding

variants of JPEG; see LEGAL ISSUES.  We have made no provision for supporting

the hierarchical or lossless processes defined in the standard.

 

We provide a set of library routines for reading and writing JPEG image files,

plus two sample applications "cjpeg" and "djpeg", which use the library to

perform conversion between JPEG and some other popular image file formats.

The library is intended to be reused in other applications.

 

In order to support file conversion and viewing software, we have included

considerable functionality beyond the bare JPEG coding/decoding capability;

for example, the color quantization modules are not strictly part of JPEG

decoding, but they are essential for output to colormapped file formats or