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.

To find out what exactly is making your PDF file big we recommend using the online PDF file analyzer from WeCompress that shows you a breakdown of the content in your PDF file. It also shows you the PDF page size, which can be a common factor in large PDF file sizes.

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.

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.

How it works

Resize images

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. The software can scale these images down to target a particular resolution for display or print.

Convert images to more efficient formats

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. The NXPowerLite software also converts many other image types to JPEG where appropriate.

Adjust the JPEG quality of images

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.

Remove private application data

Software that create PDF files, such as Adobe Photoshop or Acrobat, can store information within a PDF for use when editing the file, sometimes called Piece Information and sometimes Private Application Data. 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. Read details of how this application data is saved into PDF files.

Subset or remove embedded fonts

Most applications will embed fonts in PDF files they create. Some of these fonts can end up being quite large, so being able to remove or subset the fonts can make a big difference. NXPowerLite subsets fonts in PDF files automatically.

PDF Content Streams

NXPowerLite isn’t able to compress content streams in PDF files currently. However, we have instructions here on how to reduce the size of PDF content streams manually.

To find out what specifically is making your PDF file too big check out our online PDF size analyzer.