Mobileread
[Tool] Multi-column PDF files on 6 inch display.
#21  JSWolf 11-17-2008, 02:16 PM
Quote nrapallo
I thought the max dimensions on the Sony ebook readers were 584 width x 754 height.

I got this from page 4 of the Sony recommended pdf size.
Actually, i think the dimensions are 600x775.
Reply 

#22  soilwork 11-17-2008, 02:34 PM
Quote ProDigit
I think the problem is that we don't know what the best size is.
548x754 will be the best format for text margins in pdf.
jpg's need to use the full screen.
Making them smaller than the viewable area will result in loss of quality.
Making them larger results in loss of battery life, and display time.
Some pages I could format perfectly in 320x240 and they still will be viewable, but the quality of the page will suffer...

That is why I suggested the second option of converting into LRF. First, you can make the images with arbitrarily large resolution and then use PDFLRF or Comic2lrf. Then we don't need to worry about the correct resolution at all.

Of course, if you would like to read PDF using 1000's of splitted jpg/png/gifs, then you have to figure out the correct resolution. However, since LRF is much faster and easier to manage, I cannot think of any good reason to use image files instead of LRF.
Reply 

#23  soilwork 11-17-2008, 03:01 PM
Quote ProDigit
Those could be the recommended screensize for readable text, with a small border of 2x8 pix horizontal and a 2x23pix vertical border.
PDFLRF makes LRF based on images and it also uses 584 width x 754 height as the final output. So I don't think the resolution is only for text file. Of course, I am assuming that image based LRFs are displayed in the same resolution as image files.
Reply 

#24  ProDigit 11-17-2008, 04:05 PM
So far I did the test of the picture Sony provided on the PRS-505 of the baby.
Resizing it would give you either 800x625 or 768x600pix.
On the baby picture I could not see any difference between the two.

I will test it out with a high quality picture (with lots of detail, and probably a resolution of higher than 1MPix, of eg: grass trees and leafs) to compare each picture's size to the quality displayed.
Reply 

#25  ProDigit 11-17-2008, 05:52 PM
here are a few pictures resized all with the same settings.
I hope they work, as I'll be testing them as soon as I post this post.

Try out for yourself to see where on the reader quality decreases.
The picture is a regular picture found on google images.

Nature2 is the original.
The other formats are 8bit greyscale (256 color) versions that have lower than the original resolution.
nature2.jpg nature2 1067x800.jpg nature2 800x600.jpg nature2 779x584.jpg nature2 768x576.jpg nature2 754x566.jpg nature2 640x480.jpg nature2 512x384.jpg nature2 320x240.jpg 
Reply 

#26  ProDigit 11-17-2008, 06:17 PM
OK,I'm back with some results.
To see the pictures full screen without zoom it is hard to distinguish between files having a resolution of 754x566 pixels or greater.
When you zoom in to the max of the zoom factor, you can see that certain artifacts (pixels) are not visible on the lower qualities, but they are at 800x600 resolution.

Upon review I'll have to recode the images,seeing that the 779x548 pix. image is way blurrier than the 800x600 image.
This can have to do with the encoding being set to retain 84% of the original quality.
Tomorrow I'll re-post everything on 100% quality.
Reply 

#27  nrapallo 11-17-2008, 06:21 PM
Quote ProDigit
Nature2 is the original.
Just for comparison, this is what that image looks like using 584 x 754 as the max dimensions using PDFRead (default settings) and outputing to .lrf format in portrait and landscape modes.

BTW, this .lrf was prepared using the Sony bug-fixed pdfread.exe command line program (v1.8.2.1).
[lrf] nature2-portrait.lrf (102.3 KB, 660 views)
[lrf] nature2-landscape.lrf (136.2 KB, 657 views)
Reply 

#28  Ulysses 11-18-2008, 04:40 PM
Very good idea but it crashes all the time, maybe an option to start from a certain page would be good "work around" so we can continue where we stopped..
Reply 

#29  ProDigit 11-19-2008, 09:43 AM
Quote nrapallo
Just for comparison, this is what that image looks like using 584 x 754 as the max dimensions using PDFRead (default settings) and outputing to .lrf format in portrait and landscape modes.

BTW, this .lrf was prepared using the Sony bug-fixed pdfread.exe command line program (v1.8.2.1).
I apologise for not earlier replying, but I'm a bit busy lately.
I'll give those documents a look, and will let you know.
Obviously reducing the resolution will reduce the quality.
But perhaps in the document you post the quality loss is unnoticable.

So far on full screen (non-zoomed out) I could not detect any difference between jpegs with a greater than 754x566 pixels .
But probably it also has to do with filesize. A 754x566 pixels 128kB jpeg fil might look exactly the same as a 800x600pix 128kB file...

I'm a newbie here, and know very little of all of this, but perhaps I can help to figure out the 'best' pixel width and length for comic books.
For pure B&W (non graytint) comic books,gif is the best format. But the Sony reader does not support that format.

I'll do further testing later on.
Reply 

#30  Taesoo Kwon 11-19-2008, 11:57 PM
Quote Ulysses
Very good idea but it crashes all the time, maybe an option to start from a certain page would be good "work around" so we can continue where we stopped..
I hope the problem will disappear after downloading the version 0.3.
If it continues to crash, please send me the PDF file to me by e-mail.
Reply 

 « First  « Prev Next »  Last »  (3/10)
Today's Posts | Search this Thread | Login | Register