06/30/2007 Utilities

Compression is the reduction in size of data in order to save space or transmission time. For data transmission, compression can be performed on just the data content or on the entire transmission unit depending on a number of factors.

Content compression can be as simple as removing all extra space characters, inserting a single repeat character to indicate a string of repeated characters, and substituting smaller bit strings for frequently occurring characters. This kind of compression can reduce a text file to 50% of its original size. Compression is performed by a program that uses a formula or algorithm to determine how to compress or decompress data. The algorithm is one of the critical factors to determine the compression quality.

To PDF files, compression refers to image compressing. PDF formats are usually designed to compress information as much as possible (since these can tend to become very large files). Compression can be either lossy (some information is permanently lost) or lossless (all information can be restored).

PDF is a page description language, like PostScript but simplified with restricted functionality to be more lightweight, which dues to not only a better data structure but also very efficient compression algorithms to reduce the file size to about half the size of an equivalent PostScript file. PDFs use the following compression algorithms:

* LZW (Lempel-Ziv-Welch)
* FLATE (ZIP, in PDF 1.2)
* JPEG and JPEG2000 (PDF version 1.5
* CCITT (the facsimile standard, Group 3 or 4)
* JBIG2 compression (PDF version 1.4)
* RLE (Run Length Encoding)

How to compress your PDF files with Advanced PDF Tools?

you can select the Compression, Quality, Image size options for Color, Grayscale and Monochrome images.

Image compression is where you actually reduce the data in the image by lossless compression or by lossy compression, there are different algorithms for performing this operation and we offer you the choice of all those supported by Adobe Acrobat and PDF file, include Flate, JPEG, JPEG2000, CCITT G4 etc. types.

* For Grayscale or Color, choose Flate to apply compression that works well on images with large areas of single colors or repeating patterns, such as screen shots, simple images created with paint programs, and black-and-white images that contain repeating patterns.

* Choose JPEG, quality minimum to maximum, to apply compression that is suitable for grayscale or color images, such as continuous-tone photographs that contain more detail than can be reproduced on-screen or in print.

* Choose JPEG2000, quality Lossless, to apply lossless compression with additional advantages, such as progressive display. (JPEG2000 is the international standard for the compression and packaging of image data.

* For Monochrome, choose CCITT G4 or Flate to apply a general-purpose method that produces good compression for most types of monochrome images.

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Advanced PDF Tools

Advanced PDF Tools (Upgrade from PDF Information Editor software) is a fast and easy to use utility to maintain your PDF files, it allows you to edit or add data into the document information fields of single or multiple PDF files, it also allows you to set open action, page layout, page size, page margin, page orientation, metadata, optimize for the web (linearize), compression and others into your existing PDF files. Free to try it.