PDF or Portable document files are not only the most popular but also the most preferred format for the World Wide Web. These PDF files occupy far less space than any other document files. Having said this we sometimes have a PDF document that has a very large size and is not desirable because of the time it takes to upload or download. The only option left with us is to reduce the size of these PDF files.
If the PDF file is created using a scanned file, then while scanning the file one should use what is called an adaptive compressor option that reduces the size of the output image. After having created an output image the image mode should be changed to RGB if the documents contain both text and images. An image in RGB mode occupies far less space than an image in CMYK mode. The user can also use the grayscale image mode to reduce the file size of the PDF document.
In a PDF document, images, forms, comments, bookmarks and fonts occupy a lot of space. To reduce the file size one can clean up the document to reduce its file size by not including comments and bookmarks. It is desirable that the user includes images that are vector based which occupies far less space than the GIF or JPEG images. One must also ensure that if the PDF is a text file, minimal fonts are used to create the text file and also non-embedded certain fonts that you know are likely to be available in the end users computer because fonts do tend to occupy more bytes in a PDF document.
Two other things that can reduce the file size of a PDF document are compression and down sampling. While compression of the PDF document will eliminate all the pixel data that are not necessary down sampling helps lower the image resolution. A judicious combination of all the above can help one vastly reduce the size of a PDF file.