# PDF cleaer

First, if you have some text_based pdf, for a book that has more than 500 pages, it would only take 1 or 2 MB. That kind of PDF do not require clean.

But, if you have some image_based pdf, you should. For black and white text information, those images has too many colors. If we could lower the color number to 2 types, black and white, the image size will get down dramatically.