Compared to most other document formats, PDFs support a very wide range of compression. Normally when you save your PDF documents you will be provided with options as to how you want to compress the document. It is up to you to then decide the type of compression you want to use.
Some of the types of compression that you can choose to use in your PDF documents include:
Overall JPEG is a popular type of compression that is used to compress photos and other images. Normally the quality of the images can be selected (or conversely the level of compression) to determine how compressed the image becomes and how much data is discarded.
- JPEG 2000
Although JPEG 2000 is a newer and more efficient type of compression for color photos and images. It should reduce the file size more while preserving the image quality better than JPEG. In short, unless other considerations come into play – JPEG 2000 is preferable to JPEG.
As a lossless compression, CCITT will not affect the quality of images, but can only compress monochrome images. It comes in two variants, Group 3 and Group 4 – with the latter being the more efficient.
Another lossless compression for monochrome images, JBIG2 is more efficient than CCITT and has become more popular in recent years. It only gained support from PDF 1.5 onwards, however, so compatibility issues may have to be considered.
Although recognizable due to the popularity of ZIP files, the ZIP compression in PDF is very different. It uses the underlying algorithm in ZIP to compress color or monochrome images to images that have a limited bit-range of colors. Because of that, this compression is best used for diagrams, illustrations, or graphics that have large flat areas of solid colors.
Unlike the other compressions so far, Flate is used to compress text and is very efficient compared to the other option in PDF, LZW. It does encode more slowly but will result in smaller file sizes overall – particularly in text-intensive PDF documents.
While there are other types of compression supported by PDF documents such as LZW and RLE, the list above should give you what you need to know to compress your PDF document in the most effective manner. It should be noted that aside from compressing a PDF, you can reduce its file size in other ways by optimizing the embedded font, discarding unnecessary objects, or flattening transparencies.
In some cases however you may just want to use a more basic PDF editor to extract specific pages and create spin-off documents. Later you could learn how to merge PDF files Mac to join them together again if need be. For example, you could use Movavi PDF Editor for Mac to do that.
At the end of the day with the right compression you could dramatically reduce the file size of a PDF document. The options listed above will provide you with all that you need to do just that.