What is PDF Compression?
PDF compression enables you to compress a PDF file so that you can decrease its file size and store more data in fewer bytes. The methods used for compressing the text and the images in a PDF document are different. For example, PDF compression software may use ZIP compression for compress a PDF file that contains text and JPEG to compress a PDF file that contains images. The size of the PDF file after compression depends on your choice of the compression method, how well the compression method describes the data, and how complex the original PDF document is in terms of images, multimedia, and fonts.
Which Algorithms are Commonly Used to Compress a PDF File?
Commonly used algorithms to compress a PDF file are JPEG, JPEG2000, LZW (Lempel-Ziv-Welch), Flate, JBIG2, CCIT, and RLE. Of these algorithms, JPEG is a lossy algorithm and the others are lossless algorithms. Lossy algorithms provide better compression ratios because they selectively delete some information in the file. These algorithms are used for sound and image files. Lossless algorithms, on the other hand, leave the content of a file unaltered. If you compress a PDF file using a lossless algorithm and then decompress it, you will find that the file is unchanged. Lossless algorithms are used to compress a PDF file that contains text.
Which Algorithm Should You Use to Compress a PDF File?
You can follow certain guidelines when you compress a PDF file. If your PDF file contains images with large areas of the same color or patterns that are repeating, use Flate compression. You can also use Flate for images created with paint programs and black-and-white images. If your file contains photographs with continuous tone, use JPEG. Alternatively, you can use JPEG2000, which is the industry standard for compressing image data. If your PDF file contains monochrome images, you can use either CCITT G4 or Flate.