[ProDigit]

like mentioned,the pictures so far are JPEGS not yet inserted in a lrf.
It would not surprise me if their resolution has to lower in a LRF file.
but there are several reasons why I would not include jpegs in an LRF file.
You can do the test yourself, by opening the rar on the first post,include it in an LRF and look at the results.
I'd recommend so far to use separate jpegs in a folder per book, for anime or comic books,unless their page fits in an .lrf file.
You have to know that the LRF screensize is smaller than regular Jpegs.
The only other reason to put images to LRF is if you really want them to be in one package.
Remember that images in LRF will automatically be resized to fit the screen,unlike jpegs,which can be looked at in full size!

The sizedifference between an LRF or separate jpegs is negligable,since every jpeg loses a little space on the internal flash space (probably stores files in blocks of 4kB, any file smaller or smaller of amultiplication of 4kB will be rounded off to the nearest blocksize; eg: a 58kB file will take 60kB on a disk if the formatting has 4kB blocks).
In that the difference in size between LRF or separate jpegs is negligable.

I'd also want to recommend to open jpegs in MS Paint, and save them. Paint somewhat optimizes encoding, with perhaps 2-5% loss of quality, but often resulting in a photo 25% of the original size.

For reference: my Nikon D40 camera takes 6.6Mpix images.
The filesize is about 3MB/file. They take about 40 seconds to load on a PRS-505 reader.
Opening the picture in an editing software will save the file as a 625kB file, loading time about 5-10 seconds per file.
Opening in paint after cropping/resizing to the right resolution mentioned above, and saving results in a 165kB file, with loadtime of less than 2seconds per picture.
My wife uses Gimp, and lightroom, as well as photoshop; but there's something about MS Paint that makes files much smaller!
So,try out yourself!

Also, in the beginning I'd recommend to compress images to 256tints grayscale. Now I think it's better to convert images to 256-16bit color images (in light of possible future color ebook devices).