Hi, Slava.
I appreciate very much that you spent a lot time to test those files and tell us the results so rapidly.
The photos you took are very beautiful. Are you a professional photographer?
I think the reason why JP1 and up_down_CN zoomed to "M" are quite readable is
because the two files have optimal layout and font size for the size of the display of Sony Reader.
(I originally edited them for my (6.4", 640*480 pixel) EBK reader.)
The regular letter/A4 PDFs are really problems to most of the ebook devices
since the mismatch of the layout size of PDFs and the display size of devices.
Can you rotate the JP2 into the 'half page' mode?
I think the basic problem is that
the algorithm of Sony Reader to deal with the small size text.
If the small size text can be dark rather than gray, it would be good.
Oh. Adding a zoom in/out and scroll function for the PDFs,
such as for the pictures, would be the best.
Finally, do the Sony Reader support the CJK filename well?
How many bookmarks can one book have?
Do TOC and internal hyperlinks of a PDF work well?
How fast is the time of loading and rate of paging the CJK PDFs (equal to an English one does)?
Thanks again.