Mobileread
[Tool] Multi-column PDF files on 6 inch display.
#11  zelda_pinwheel 11-16-2008, 05:01 PM
Quote =X=
Moderators can you please make this tread a sticky?
stuck.
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#12  Taesoo Kwon 11-16-2008, 06:27 PM
Quote ProDigit
Isn't it better to convert to something like 790x600 pix?
just a question.
I don't know exactly what is the best resolution for Sony reader.
Cybook and nuutbook (a netronix variant which I use) displays images at full screen, so 600*800 was the best for those devices.
The resoultion can be changed by editing config.lua.
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#13  soilwork 11-17-2008, 01:53 AM
Hello, I found some bugs in version 0.24

- Every time I try 'process all pages', at the end, I got a dialog box saying
"Do you want to overwrite file \...\00000_000.jpg?"
If I answer yes, the last image overwrites the first file (00000_000.jpg).

- In some cases, the original PDF uses one font throughout the page, but the conversion results look different.
Please refer to the pictures attached. In the original PDF, all of them have the same font.
This bug does not affect usability but it is a bit strange.

- The program crashes with some files. If you would like, I will email PDF files causing the problem.

Thanks again for the great program.
original.png converted.jpg 
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#14  ProDigit 11-17-2008, 12:20 PM
Quote Taesoo Kwon
I don't know exactly what is the best resolution for Sony reader.
Cybook and nuutbook (a netronix variant which I use) displays images at full screen, so 600*800 was the best for those devices.
The resoultion can be changed by editing config.lua.
Yes I understand that, since the readers use a 800x600 screen.
However there is a small bar on the bottom on the reader,about 5mm in size (0,2"). I could imagine every reader has this bar with either some battery life info, page info, or whatever...
Is this bar hovering over the picture, or taking some space off the picture?
I say this because having a book (manga for instance) with 200 pages of jpeg compressed, at a resolution of 800x600 or say 790x600 could save up some hundreds of kB, to a few of MB's in size.
If you don't notice the difference anyway, plus, then the reader can literally input-output the image on the screen without internal resizing and rendering.

Yesterday I thought my reader froze when I plugged in an SD card with a photo my wife took from her Nikon D40 camera. 6MPix, 4,6MB in size. It took about 5 to 7 minutes to first render the picture.
After editing (resizing to 800x600,& saving as B&W) the image only took up 96kB of size (=below 100kBytes).
You couldn't see the difference in full screen view between the two, I saved about +4MB in size, and the reader rendered my 96kB image within 2 seconds.
For books that need no zooming in,or tiling to landscape it is much better to save them this way.
To bring it further I wanted to know if someone knows something about the bar displayed.
If it hovered over, or took space off the screen.
I believe if the reader does not need to render nor resizing the image, some more battery and loading time could be saved.
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#15  nrapallo 11-17-2008, 12:46 PM
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.
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#16  ProDigit 11-17-2008, 01:32 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.
Those could be the recommended screensize for readable text, with a small border of 2x8 pix horizontal and a 2x23pix vertical border.

Though I prefer text without border, since it takes up screen space, and you already have a border around the screen. (I mean it's not like we can make annotations on these devices or so).

when I load a pdf,with this info, and zoom on text width, I notice that the left,top and right border are the same size.
So let's assume you have a border of 8pix left,up and right of the text.
This leaves a border of 38 on the bottom.
take 13 pix of the bottom border since it seems a little larger than the others, and you'll have a bar on the bottom of about 25 pix.

in other words it could be that images with a size of 775x600 are displayed exactly the same as 800x600.
In order to figure that out I can try to see if I see any difference between the quality of 800x600 and 775x600.
Obviously 775x600 will be more stretched looking.

However I had preferred if someone knew by playing around with the internal software what the exact resolutions are.
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#17  soilwork 11-17-2008, 01:37 PM
As TaeSoo and nrapallo mentioned, you can change the output resolution by modifying two lines of 'config.lua'. You can change the first two lines to these.
Code
device_width=584
device_height=754
Better yet, you can convert set of image files into LRF using comic2lrf of Calibre. First, make one zip file from the pictures then use a simple script such as
Code
comic2lrf -c 8 -r 'file.name.here.zip'
I think it will be easier to manage one LRF file instead of hundreds of images.
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#18  nrapallo 11-17-2008, 01:47 PM
Quote ProDigit
In order to figure that out I can try to see if I see any difference between the quality of 800x600 and 775x600.
Obviously 775x600 will be more stretched looking.
It shouldn't look stretched if the original image's aspect ratio is maintained, just a bit more white margin space in lieu.

Now if PaperCrop does in fact stretch it to fit, then you would have to override this behaviour to get non-stretch/squished resulting images.

In the end, there is no right/wrong way to do this; it's a matter of personal taste/preference i.e what you like to use!

Quote
However I had preferred if someone knew by playing around with the internal software what the exact resolutions are.
Trial and error and a bit of sweat equity is always needed when charting unknown territory...
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#19  ProDigit 11-17-2008, 01:48 PM
Quote soilwork
As TaeSoo and nrapallo mentioned, you can change the output resolution by modifying two lines of 'config.lua'. You can change the first two lines to these.
Code
device_width=584
device_height=754
Better yet, you can convert set of image files into LRF using comic2lrf of Calibre. First, make one zip file from the pictures then use a simple script such as
Code
comic2lrf -c 8 -r 'file.name.here.zip'
I think it will be easier to manage one LRF file instead of hundreds of images.
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...
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#20  nrapallo 11-17-2008, 01:53 PM
Oh, another bug after editing the config.lua, the resulting .png images are of size of 473 x 595 even though I set 472 x 595 as the max. dimensions my reader expects. This is probably a rounding-off problem...
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