PDF file format is a document file format created by Adobe System, which is very versatile and platform independent. PDF acts like a container holding several data objects such as text, images, font data, etc.

Default uncompressed PDF files can sometime take up a lot of disk space. This is due to un-optimized images and vector text objects inside it. This can be a major problem as transfer of the documents becomes almost impossible over low bandwidth networks. Since upgrading the network infrastructure is a costly solution, stress is laid on optimization of the PDF files. Several techniques have been developed to shrink PDF size. Several third party software such as PDF compress, PDF Shrink, etc. are available which compresses the PDF files automatically. There are few freeware available to do the same too.

In case the user uses MAC OS, he/she can shrink PDF size by optimizing the color table of the image. This can be done by using the color sync>quartz filter. This results in a smaller PDF file because the size of the PDF is directly affected by the images contained in it.

Several algorithms to shrink PDF size are available. They are generalized algorithms (Lossy and Lossless) which can be applied to both image and text. They work by reducing the repeated or redundant patterns in the data, and replacing them with a single pattern with some pointers associated with it. They can achieve a fairly good amount of compression and can shrink PDF size by more than 40% easily.

If the image contained is in a high quality format, its quality can be reduced and be re-imported as JPEG images. Images can also be down sampled to reduce its size. A user can also optimize the print quality of the PDF files. The print quality of 300 DPI is recommended for normal printing and 1200 DPI for commercial printing. Higher the print quality of the PDF file, higher will be its size. Hence properly optimizing it will also help shrink PDF size.

Optimizing to shrink PDF size is the most cost effective solution for the problem of large PDF files over low bandwidth networks and it helps in saving up a lot of disk space in computers with large number of documents.