The idea behind document compression is to make a large file smaller, without losing the data, or document quality. You may want to compress your documents for many reasons, such as reducing storage space. In files used over networks, reducing size is also equivalent to saving on transfer time.
All of us want to make our documents/ presentations interesting and easy to follow, with graphics and interesting fonts. However these are the very elements that add bulk to the document files. This is more so in PDF files, which can be large in size, and become larger when pictures or uncommon fonts are added, or several edits are done.
The trick therefore is to reduce the size of the graphics and do away with non essential elements. However this has to be achieved without compromising on the quality of the document. Some programs embed images at resolutions that are higher than required for reasonable display needs. If size is reduced here and compressed, a lot of space can be saved.
Compression techniques can reduce the size of a document into a tenth or even hundredth part. If used carefully, compression can focus on noise (unwanted disturbances in the picture) and eliminate it, thereby even improving quality of the graphic while reducing size. This method of sorting out noise and signal while compressing is known as perceptually lossless compression.
Since compression of documents involves change of data bits, care has to be taken that it does not produce degraded data. There are different versions of the same compression standards available commercially. Therefore it is important to understand which works in what situation. A good way to do this is to test the fidelity of the original and compressed document using systems like optical character recognition (OCR).
There are many advantages to compressing documents. The obvious one is the saving on storage space. Document compression also allows files to be emailed, opened, transmitted, and accessed faster. Many companies today host and share their documents online and need to distribute their databases. Compression can save sometimes upto 90% of available storage space. This in turn brings down web hosting, archiving and storing costs significantly. Another factor that improves is time requirement for transfer of files over the Internet or the companys own network.