PDF Compression

PDF files are most often scanned physical documents or documents that have been created entirely digitally often referred to as 'native' or 'born digital' PDFs. NXPowerLite is able to reduce the size of both types of PDF by resizing images, adjusting image formats and quality levels while removing background or hidden data that isn't needed for normal use of the file.


Scanned PDF files

Scanners often capture document pages as high resolution images without compression. So even documents that appear to be just text can often be entirely images. By reducing the resolution of these images and choosing an efficient image encoding these files can be dramatically reduced.

Original file  Page resolution: 2481 x 3507 Image encoding: Uncompressed File size: 9 MB

Original file
Page resolution: 2481 x 3507
Image encoding: Uncompressed
File size: 9 MB

Optimized file  Page resolution: 1654 x 2338 Image encoding: JPEG File size: 2 MB

Optimized file
Page resolution: 1654 x 2338
Image encoding: JPEG
File size: 2 MB


Native PDF files

PDF files generated from an electronic source - such as a Word document, a computer generated report, or spreadsheet data - will usually be formed of a combination of text and images. For this type of file NXPowerLite ignores the text and focuses on resizing and choosing the best format for the embedded images. 

Original file  File size: 8.3 MB

Original file
File size: 8.3 MB

Optimized file  File Size: 1.9 MB

Optimized file
File Size: 1.9 MB



Description File size Reduction File link
Original scanned PDF 9 MB 0%
Optimized scanned PDF 2 MB 78%
Original native PDF 8.3 MB 0%
Optimized native PDF 1.9 MB 77%

How it works


Images are often inserted into PDF files at much larger sizes than necessary. For example, a photograph taken by a digital camera might contain five million or more pixels, but most of this detail will not be visible unless 'zoom' controls are used. NXPowerLite can scale these images down to target a particular resolution for display or print.



PDF files allow a wide range of inefficient image formats to be stored inside them natively. NXPowerLite converts bi-level (black and white) images to lossless JBIG2 encoding, which typically generates files one third to one fifth the size of CCITT Group 4 encoding. NXPowerLite also converts many other image types to JPEG where appropriate.



NXPowerLite can also apply additional compression to images that are already in the JPEG format. This can squeeze out impressive additional savings without noticeable loss of quality, even at 100% zoom.



Applications that create PDF files, such as Adobe Photoshop or Acrobat, can store information within a PDF for use when editing the file. This information can only be used by the application which created the file and is not needed to display the PDF. For most cases we recommend deleting this data, as it will have no effect on the use of the PDF file.

Official Adobe® PDF Technology

We use the official Adobe® PDF Library to ensure our PDF compression software is robust and reliable, it is the same technology that Adobe® uses to build Acrobat®. 

“A unique file optimization solution that eliminates unessential data, converts graphics to the most efficient format and resolution, dramatically reduces the size of content-rich files, and increases efficiency and bottom line cost savings, all while keeping the file basically intact.”
— Terri McClure, Senior Analyst, Enterprise Strategy Group