Convert a pdf into cbz format

Cbz format is a standard format for comics & magazines. It is just a zip file with the files saved as jpg / png files inside. Cbr is the other format but that is rar format instead of zip. The images should be saved as 00.jpg, 01.jpg etc, so that the page ordering is preserved. The advantage of cbz format is that viewers are lightweight and load a lot quicker than pdf files, and they also can be viewed on laptops rotated by 90 degrees to use the full screen area.