send to kindle resolution

[darodi]

Hello @celogeek

For your information, some people have reported that send to kindle is limited in resolution.
Down scaling to 1440x1920 might give the same result, but with more pages possible with the same size limit constraint -limitmb

@darodi I have sent recently several epubs to my Scribe using Send to Kindle via web. They are converted to AZW3, and to the best of my recent experience the image resolution is still downscaled (down to 1440x1920).
Originally posted by @nicoladicicco in ciromattia/kcc#460 (comment)

[celogeek]

Interesting. So amazon downgrade the image to a lower resolution.
The 1920x1440 as an aspect ration of 1:1.33 like the resolution of the kindle.

Amazon advice to use a ratio of 1:1.6, so image of 1920x1200 should be good enough.
But they also say if you are using zooming to send an image of twice this size: 3840x2400 ...

I create some HR profile, specially when you are using tablette or something else.
I will create a standard profile with the 1920x1200 resolution. It could be great then to upload HR & standard, and then compare what the kindle received.

If you are using kindlegen or kindlepreviewer -convert, do we have this limit ? like sideloading directly ?

[celogeek]

Here: https://kdp.amazon.com/en_US/help/topic/G9GSTY4LTRT39D4Z

[celogeek]

I've extract the AWZ3 I receive from the device. I used calibre to convert this into a zip.
The height is 1920 all the time, but the ratio is the one I've set.
I've got: 1226x1920, 1:1.56 for example.

It looks to be the maximum height allow. If it's lower, it keep the size.

I will see if I can create an AZW3 with higher resolution. I only know calibre that can do this. I wonder if they are library or tools that allow to create this format directly.
May be this format is a kind of simple zip with some html ... I need to study this.

[celogeek]

I try kindlepreview epub -convert of my HR files.
It generate a mobi.
My epub size = 245M
The images size are 1814x3031 (3031 max)

The mobi size = 384M !
The images size is 1920x... or ...x1920 (max 1920 for width and height)

I can copy the file to the kindle, it works. So epub -> kindlepreviewer epub -covert, allow to copy the content to the kindle without the 200mb limit, but still, the image resolution stay limited like the website.

I see they is a GoLang module to create AWZ3 files directly !
It would be very interesting to be able to generate this format instead of the epub (or both may be).
And good point, is that I won't need external tools to do it.

I will do some test.
In the mean times, I will add a profile for the 1920 resolution, it will be far better for the size of the epub with the current limitation.

[celogeek]

When I try with a standard resolution, the mobi size = 246M instead of 384M.
But when I ask calibre to transform to zip or epub, it's very fast, and the size of the file is 126M.

So Mobi from HR = 384M, Epub from it = 126M
Mobi from SD = 246M, Epub from it = 126M
Both image in the epub has 1920x max.

So the mobi is bigger from the bigger image. I wonder if the extract from calibre is not the one that truncate the image after all.

[darodi]

with kindlegen you should use -dont_append_source to get a correct size.

kindlegen -dont_append_source -locale en inputfile.epub

it is present in \AppData\Local\Amazon\Kindle Previewer 3\lib\fc\bin\

[celogeek]

Trying.
The 1920 image size convert in few sec.
The bigger file take times, so I guess it's resizing (not in parallel).

SD = 124M
HR = 129M

Right, so it's clearly downsize here.
This "dont_append_source" seems to be an hidden parameters.
Why do they add the original source in the mobi ? is that for higher resolution screen ? or just to have a copy of the source there ? But it will be useless when we want to read this on device right ?

[darodi]

Why do they add the original source in the mobi ?

I guess, since Kindle Previewer 3 is used mainly for books and later, for sending to amazon and publishing to kindle store.

[celogeek]

Any chance the high resolution device use this source image instead of the compacted version ?
The sendtokindle website strip the source too ?

[celogeek]

I create the profile SR: Standard Resolution: 1200x1920 (aspect 1:1.6)
It max out what amazon support.
The size of the file is close to the mobi now.
The speed of conversion is awesome.
I've just send 110 comics, with 100M each, it take less than an half an hour.
I can see email incoming while I was sending batch of 20.

So I wonder if that really necessary to have all of those profiles finally.
And HR and SR is enough I guess.
HR if you don't use Kindle, and the reader support large image.
SR for kindle conversion and/or reasonable good size/quality.

Every other kindle may have smaller size result as I guess it won't display it better with larger image.

The advantage of the SR is that you can put the comics in the cloud, then read it on any kindle device you've got.

[darodi]

Out of curiosity, do you get the same result with a pdf input and send to kindle?

[celogeek]

I've read that PDF put directly on device vs PDF sent in the cloud have different feature on the device.
I haven't check, the size and quality, but when I use the cloud, I have Advanced TypeSettings activated.

So I can change the contrast on device (I like this feature, but it's only for PDF sent in the cloud), and I think orientation.
But I don't have like ePub spreading 2 pages on the screen, or manga mode.

So PDF is more a static version of what you want in normal mode.

Also on GoLang I've found some module to create Mobi (PalmDoc).

I also find a module that is an helper for created KF8-style formatted MOBI and AZW3:
https://github.com/leotaku/mobi.

And the same author create a tools to convert manga directly to AZW3 that can be sideloaded on device.
https://github.com/leotaku/kojirou.

The generated file should have less feature as the one from amazon, but I note to try with bigger image in this.
I know mobi has limitation, so I will see if that is one.

[celogeek]

I've done a test with kijirou tools and my local png.
So I've got full resolution scan with 1920x3031 size, color, in PNG format.

The tools will convert it to JPG but that's it, same resolution, same color, and default quality.
The image size vary from 300kb to 1.7mb. most are around 800kb.

I copy it to my kindle, I've got the thumbnail and the book that is working.

So definitively that's an interesting option I can add to my tools.
Like export-format: epub, awz3

[celogeek]

It seems PDF support improved lately. I will check again. Stuff like 2 pages on landscape ...

[celogeek]

PDF is not so good (no way to deal with double page properly, and landscape/portrait) and image are resized.

So the best for now is the SR profile I create with resolution of 1200x1920
This one won't need resizing from amazon and will have super fast processing speed.

It works on all devices, so best think I can do right now.

Creating AWZ3 in a custom format is also a solution, as it seems we can set a higher resolution.
I'm not sure it has a better rendering at the end.

May be we should wait that amazon increase the resolution they support with their conversion tools.

[romancin]

So I've got full resolution scan with 1920x3031 size, color, in PNG format.

Thank you for this test! I have tried it, I I really notice the difference between mobi using go-comic-converter and azw3 file generated from images in disk using kojirou. AZW3 It is MUCH sharper on Kindle Scribe.

It would be awesome if you can integrate awz3 generation the same way kojirou does :D

[celogeek]

@romancin Good to know ! I was wondering. I will see what I can do.
I don't know if I can do everything I do with the ePub, I will need to try.
holidays soon, best time to do this kind of stuff ;)

[romancin]

@romancin Good to know ! I was wondering. I will see what I can do.
I don't know if I can do everything I do with the ePub, I will need to try.
holidays soon, best time to do this kind of stuff ;)

Awesome! Thank you very much! I can test everything you need in my scribe :)

[celogeek]

Got a scribe too and use it to test, and an Oasis for smaller device ;)

[romancin]

Hi again @celogeek ! Any news on this? It is still not possible to use native Scribe resolution?

[celogeek]

Sorry, not yet. I've got plenty of update to do, I need to find time for working on it.

The primary goal of the project was to allow creation of ePub that can be uploaded to the AWS cloud and then the ability to read it on any device.

I need to create a todo list