PDF /MOBI max image size on Kindle 2

[jaypeecee]

Hello all -

I've searched around a bunch, and apologies if I've missed the answer, but I'm trying to figure out the maximum image size that the Kindle 2 will display inline in a PDF without having to resize or resample them. Here's a little background:

I have a few graphic novels that I'm trying to convert to read on the Kindle 2, but being a perfectionist I want to get the biggest and clearest images possible. I have them as numbered JPG's right now. So far I have:

1. Created a .CBZ; the images fill the screen and look great, but navigation stinks and after a while the Kindle chokes on the images and crashes.
2. Created a .MOBI from the files using Calibre; it looks fantastic and I can click to zoom (the zoomed images fill the screen completely and look great), but the inline images are small (~80% of reading area) and having to zoom on each image is a pain.
3. Created a .PDF using Acrobat Pro; navigation is great, images fill the screen, but the images look mushy and cruddy compared to the MOBI or CBZ.

So, given the above, for these graphic novels, PDF seems to be the best choice to balance image size and navigation ability (can skip to location/page), IF and only if I can get the images to not look like crud. So, while I know the screen resolution is 800 x 600, but with the status bars at the bottom and the top, the viewing area for images in PDFs must be smaller. I figure if I can resize the images to be the correct dimensions, the images will look nice and crisp and the PDF graphic novels will be readable.

This is assuming that the images in the PDF look awful because they're being resized on the fly, and the Kindle is making them all artifact-y as it resizes the JPG's.

Also, if there is some trick to getting inline images to look bigger when embedded in a MOBI file, please let me know. I've trimmed the borders from the images - the format or Kindle seems to make them smaller than the full viewing area (which is what pushed me towards converting to PDF, as the images seem to be able to take up more of the viewing area).

Any help would be appreciated!

[jaypeecee]

Perhaps this is part of the puzzle, but it's unclear if this would apply to a PDF that is just a collection of images with no text/formatting:

https://www.mobileread.com/forums/sho...438#post530438

[acidburn517]

Have you tried converting the images using Mangle? http://foosoft.net/mangle/

It optimizes the images for the resolution of the Kindle and let's you organize them in folders in your picture viewer.

There's a step by step tutorial on how to use the program here:

http://barngamerz.com/how-to-get-man...by-step-guide/

[jaypeecee]

I thought about something like that, however: I'm on OSX, and don't want to compile my own version of Mangle.

Also, browsing as pictures does not allow for the navigation that PDF or MOBI do (jump to page... add notes in MOBI, etc).

[lilman]

According to the article here: http://kindleformatting.com/blog/2009_06_01_archive.php, the usable K2 book space is 520px x 622px. I think they are talking about books though and not pdfs, but maybe try those specs and see how they look. I don't have a K2 but on my DX I don't think any of the width of the screen is wasted in pdf mode, only some of the height at the top and the bottom of the screen is reserved.

If you are looking for an image processor you can try my manga app: https://www.mobileread.com/forums/showthread.php?t=75628. You can specify width, height, dpi, color mode, zip output (.zip or .cbz), and pdf output. Right now it only works in batch mode, so if you want to process a single folder "X" you would have to place it as a subfolder in a parent folder "Y" and then run the program. In my next update to the program I will add single folder mode.

[jaypeecee]

Creating a folder of images doesn't allow the "jump to page" functionality that really makes reading these more book-like (which is what I'm trying to preserve). Particularly because some of these are in the hundreds of pages.

So far by resizing the images to 622 tall (they end up narrower than the allowed K2 screen area) and making a 500 DPI pdf, the images still end up looking kinda crummy. Or at least not as good as the full size images in a CBZ converted into a MOBI (though it only takes up a fraction of the usable screen area) and then zoomed in on using the 5-way selector (they look amazing in fullscreen that way).

Any idea how to either boost the size of the images displayed inline in MOBI files to the full 622 x 520, or how to get any size PDF images to look as good?

I can try and post screen shots if it would help to illuminate the difference.

[lilman]

Originally Posted by jaypeecee

Creating a folder of images doesn't allow the "jump to page" functionality that really makes reading these more book-like (which is what I'm trying to preserve). Particularly because some of these are in the hundreds of pages.

Yeah I know what you mean. That's one of the reasons I like pdf over image zips for manga.

Originally Posted by jaypeecee

So far by resizing the images to 622 tall (they end up narrower than the allowed K2 screen area) and making a 500 DPI pdf, the images still end up looking kinda crummy. Or at least not as good as the full size images in a CBZ converted into a MOBI (though it only takes up a fraction of the usable screen area) and then zoomed in on using the 5-way selector (they look amazing in fullscreen that way).

Well increasing the dpi above the K2 supported 167dpi shouldn't help the images look better (it will add to your file sizes though, and it may add some processing time too). So 622 is still not the right height in pdf mode... I haven't come across any documentation that says the usable space in pdf mode. I guess you could try to measure it yourself by displaying a solid black full screen image, measure the top and bottom margins using a ruler, and then use mathmagic to determine the number of pixels used in the margins: 800 - (167 pixels per inch x size of margin in inches). That should give you a better estimate.

Originally Posted by jaypeecee

Any idea how to either boost the size of the images displayed inline in MOBI files to the full 622 x 520, or how to get any size PDF images to look as good?

I can try and post screen shots if it would help to illuminate the difference.

I'm unfamiliar with the mobi format, but sure post pics and maybe someone here can help you.

[jaypeecee]

Thanks for the thoughts. I'm starting to think that the issue lies in the Kindle 2's software itself. If I convert a bunch of images to .MOBI with the "no image processing" option in Calibre from large, high-quality images and also create a PDF on the computer with zero image processing (just combining the JPG's into a single PDF), they both look fantastic on the computer screen.

BUT, when loaded onto the kindle the .MOBI images look just as great as on the Mac (though they're limited to 622 height as per specs until zoomed manually), however the PDF images, while full screen (which is nice), look like garbage.

This leads me to believe that the Kindle's "experimental" PDF support just handles images in a nasty way. Perhaps the 2.5 software update that offers PDF zooming will also have cleaner image rendering/support?

Does anyone else know of/have experiences where the images embedded in PDFs were uglier than the same images displayed in the Kindle 2's CBZ/image viewer?

[acidburn517]

I"m having similar issues. I tried to use calibre last night to do some conversions and the pages just don't fill the whole screen for me either no matter what settings I change it to. Browsing through the calibre thread here https://www.mobileread.com/forums/sho...t=27783&page=7 it looks like some people are having similar issues with the kindle 2 but not other readers. I would suggest maybe posting the questions there since kovidgoyal who made calibre seems to be answering questions there with regards to the program and modifying the program as needed based on the issues that come up. It might be a settings thing in terms of the output. People with sony readers don't seem to have similar problems.

[jaypeecee]

I've added my comments to the thread you mentioned, over here.

It does seem to be the Kindle's fault. If the PDF viewer didn't mutilate high-quality images as it displays them (it displays them just fine using the MOBI display engine), then we'd be home free. Sadly, until they improve PDF support, there's no elegant solution that combines full-screen, high quality page views and the ability to navigate/jump to page/bookmark, as the Kindle's CBZ or image viewing support is severely lacking for the reasons mentioned in the beginning of this thread.

[lilman]

Originally Posted by jaypeecee

as the Kindle's CBZ or image viewing support is severely lacking for the reasons mentioned in the beginning of this thread.

Agreed, the kindle image viewer is way too slow when changing images, and lacks other functionally such as page jumping, to make it useful at this point.

It's a shame the K2 pdf mode is mutilating the images. On the DX pdf images look just as good as in the image viewer.

[jaypeecee]

That's one of the reasons I started this thread - it does seem curious. I think the DX has better PDF support baked-in on purpose (textbooks), but to echo my original plea:

If anyone knows any tricks to get images in PDFs to display on the K2 without degradation, please chime in!

I've tried playing with image sizes, PDF settings, image DPI, etc etc etc to no avail thus far. Still far cruddier than in the Kindle image viewer.