Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

What is Compression Gain?

Posted on 2004-04-05
1
Medium Priority
?
299 Views
Last Modified: 2010-04-03
Can someone please tell me what is meant by compression gain.
I have compressed a text string with LZW, the efficiency before compression is 99.5% and after compression 92.3% using:
(Entropy / Av Codeword Length) * 100
It takes 50 bits to encode the data before compression and 60 bits after (so its not really worth compressing with this method).

So is the compression gain simply a bit value (ie 10 bits) or is it related to the efficiency (ie 99.5 - 92.3)

Thanks In Advance

Rick
0
Comment
Question by:jondow
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
1 Comment
 
LVL 1

Accepted Solution

by:
juliangkeller earned 100 total points
ID: 10760190
I don't know if this helps:

http://www.dogma.net/markn/articles/lzw/lzw.htm

It does refer to bits because it is compressing data. In some cases it is possibly to acheive 30% gain (i.e 100 bits to 70 bits) but is not for all data as you seen yourself that it can raise the bits and lower the percentage.  

You can see about that here:

http://64.233.167.104/search?q=cache:fd9kx-VFXPMJ:biron.usc.edu/~sagetong/Project_3.doc+LZW+compression+gain&hl=en&ie=UTF-8

http://66.102.7.104/search?q=cache:6UG4nkjb6ZUJ:www.cms.livjm.ac.uk/pgnet2003/submissions/Paper-13.Pdf+LZW+compression+gain&hl=en&ie=UTF-8

PAGE 4 ON THE RIGHT
most people don't use LZW because of this unless it is a large file and some in Unix because PKzip is not useful.

I hope this helps.
0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The business world is becoming increasingly integrated with tech. It’s not just for a select few anymore — but what about if you have a small business? It may be easier than you think to integrate technology into your small business, and it’s likely…
Compliance and data security require steps be taken to prevent unauthorized users from copying data.  Here's one method to prevent data theft via USB drives (and writable optical media).
This tutorial will walk an individual through the process of installing the necessary services and then configuring a Windows Server 2012 system as an iSCSI target. To install the necessary roles, go to Server Manager, and select Add Roles and Featu…
This Micro Tutorial will teach you how to reformat your flash drive. Sometimes your flash drive may have issues carrying files so this will completely restore it to manufacturing settings. Make sure to backup all files before reformatting. This w…
Suggested Courses

636 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question