I downloaded some Chinese books in PDF format from the net. On my MBP, they displayed without any problem, but not in GoodReader or iBooks on my iPad. They showed up as blank pages! Per the Troubleshooting tips in GoodReader's Help file, it turns out that these PDF files are encoded with JPEG 2000 image compression. Since the current iOS does not support this compression method, and GoodReader and iBooks rely on iOS's processing of PDF's, neither app is able to display the PDF documents encoded with JPEG 2000 on the iPad! I followed GoodReader's suggestion to have saved a separate copy of the same PDF document on my Mac. While this copy correctly displayed on my iPad in both GoodReader and iBooks, the file size ballooned from 3.8MB of the original file to 138MB!!! That's over 30 fold increase in size!!! Acceptable??? So the question is: when is iOS going to support PDF documents that are encoded with JPEG 2000 compression method? And why isn't it now??? Please note: I am not someone who posts a lot. It's just that the problem is annoying. I read PDF books a lot, and some of them are encoded with the JPEG 2000 image compression method. Can you imagine carrying 100 plus MB per file on your iPad, whilst its original size is merely a few MB's?