A question about comic2ltr/epub

[moggie]

Two questions really:

1. Should I be converting files to epub or ltr, which is the better format.
2. I don't actually have the sony reader yet, I bought it today but it's a Christmas present ( My wife is buying for me ), however I did take a SD card to the shop to make sure I would be happy with it. I discovered the landscape option but I noticed that comic2ltr didn't seem to be putting enough pixels in and the reader was interpolating. Would it be possible to put enough pixels in the image so that it had to reduce the image for portrait viewing but there was enough pixels so that in landscape I could see them all ?

Ps I told the people at the Sony shop about caliber so they could mention it to other customers who had mac's or Linux systems.

[JSWolf]

I find the 505 does a pretty good job dithering more than 8 shades.It may depend on how many colors the conversion is using. if you convert to LRF, use lrf2lrs to get at the images and see what happened to them. See if the resizing and/or dithering might be what the problem is.

[kovidgoyal]

comic2lrf has a --landscape option

[moggie]

I am using the following code:

#!/bin/bash
IN=$1
OUT=`echo $IN| sed -e 's/\.cb.$/\.lrf/' `
if [  -f "$OUT" ];
then
        echo skipping $OUT
        exit 0
fi

comic2lrf -w  -l -r  "$IN" -o "$OUT"

What I mean is that the screen is nominally 584x754 pixels, if comic2lrf generated images that where 754x1168 would ( well 754x973 ) would the reader display them correctly in portrait mode but also show them better in landscape as it has enough information to show the picture better ?

[kovidgoyal]

Ah you want images that work in both portrait and landscape mode. It's a trade-off. comic2lrf performs rescaling and dithering that (typically) result in an image that has more legible text than the rescaling routines on the reader. It could generate images larger than the screen size and have the reader rescale, but you would lose quality.

[moggie]

Originally Posted by kovidgoyal

Ah you want images that work in both portrait and landscape mode. It's a trade-off. comic2lrf performs rescaling and dithering that (typically) result in an image that has more legible text than the rescaling routines on the reader. It could generate images larger than the screen size and have the reader rescale, but you would lose quality.

I understand that a large computer can do a better job than a little one . What I want to know is is it possible to generate a lrf which looks okay in portrait mode but looks best in landscape ( where the reader show half a page at one time, I don't know if this is what you call landscape, but I saw the option under settings/advance/orientation ).

[kovidgoyal]

I'm not sure why you want that? In any case, it isn't possible with comic2lrf

[moggie]

Originally Posted by kovidgoyal

I'm not sure why you want that? In any case, it isn't possible with comic2lrf

I had a quick thought overnight, why couldn't you use a different profile effectively to optimise for the screen the other way round ?

[kovidgoyal]

Doesn't the -w option do that already?

[moggie]

Originally Posted by kovidgoyal

Doesn't the -w option do that already?

I don't believe so, run a file though the filter twice. Once with and once with out the -w flag and compare the files sizes. The one for landscape should be significantly bigger as I would expect it to have more pixels in it.

comic2lrf -w  -l -r  foo.cbz -o foo-w.lrf
comic2lrf  -l -r  foo.cbz -o foo.lrf
-rw-r--r--  1 jb23  jb23  1760754  1 Dec 09:46 foo-w.lrf
-rw-r--r--  1 jb23  jb23  4775249  1 Dec 09:45 foo.cbz
-rw-r--r--  1 jb23  jb23  1760753  1 Dec 09:47 foo.lrf

[kovidgoyal]

What the -w option does is "Keep aspect ratio and scale image using screen height as image width for viewing in landscape mode."

[moggie]

Maybe I am not being clear, and remember this is from observations for about 10 minutes.

I want the file to be optimised for landscape, that is to have enough pixels so that in landscape mode then the image will not be resized. I realise that the image will be resized if viewed in portrait mode.

I am sorry if I am not being clear does the above make sense as a request ?

[kovidgoyal]

Ah I think I understand now. You want a profile that sets the image width <= screen height and image height <= 2*screen width

Is that right?

[moggie]

Originally Posted by kovidgoyal

Ah I think I understand now. You want a profile that sets the image width <= screen height and image height <= 2*screen width

Is that right?

Yes, although I have a suspicion that it will not be exactly that because of the bits of the screen used for the user interface are slightly different in the two modes.

[moggie]

Ticket http://calibre.kovidgoyal.net/ticket/1331 created