Enable kindle's auto-image upscaling in mobi?

badbob001 · 02-21-2015, 12:13 PM

I have epub books that are about 99.9% images (eg: Diary of a Wimpy Kid) and when viewed as mobi on my Kindle Voyage, the images don't fill the screen and thus are too small to comfortably view. I suspect the images would look fine on a lower-resolution kindle but not on the voyage. I could long-press the image, click the magnifier to expand the image to fill the screen, but I have to do this for every page.

When testing converting comics files using different apps (mangai or kcc), I've noticed that the kindle's mobi viewer will automatically crop out white margins and upscale images to fill the screen. I'm not sure if this only works for white margins in the actual image or if it would work with the white margins in the html page (which is the situation with the epubs), but this feature may help resolve my issue if there is a way to enable it. I think this is a feature of the mobi reader in the paperwhite as well.

I don't know what special setting needs to be set in the mobi to enable this feature. When this is happening, the menu has these options:
* Animation On/Off
* Fit to Screen On/Off
Note that I'm not aware of a way to DISABLE the automatic margin trimming/image upscaling for these documents.

Otherwise, are there any other options in the conversion process to upscale these images, either by actually upscaling the images or some sort of width=100% html setting? In calibre, when I edit the epub, I see the html simply has each image in a separate <p> tag:

Code:

<p class="image"><a id="page_124"/><img alt="Image" src="../images/f0124-01.jpg"/></p>
<p class="image"><a id="page_125"/><img alt="Image" src="../images/f0125-01.jpg"/></p>
<p class="image"><a id="page_126"/><img alt="Image" src="../images/f0126-01.jpg"/></p>
<p class="image"><a id="page_127"/><img alt="Image" src="../images/f0127-01.jpg"/></p>

badbob001 · 02-23-2015, 04:56 PM

I even tried switching from mobi to azw3 to see if perhaps something got lost in the conversion from epub due to the older mobi format.

I'm guessing I need to enable "Panel View" for each page, but sadly I don't see that option for mobi/azw3 settings. How is that "enabled" physically in the ebook anyway?

I spent some type looking at the css of the source epub, tried modifying the "image" class and was dumbfounded to why it didn't affect the image. Then I realized that the "image" class only affected the <p> tag.

Now I can either add a "height=100%" to all of the <img> tags, add a "img" class to the css (may affect more images than intended), or create myself a new class (eg: class="imagepage"). But don't think I'm some css genius as I just use google for help on that and I'm basically a html 1.0 guy.

It seems rather silly for ebooks to have a fixed-resolution mentality in their creation. I see options in Calibre to adjust text in the conversion, but really nothing for graphics. Maybe add some logic on when to modify a page to upscale image / enable Panel View? Like if the page no text but one large graphic?

badbob001 · 02-23-2015, 06:06 PM

I found a post about using this meta tag to set a book to comic-type:
<meta name="book-type" content="comic"/>

The post mentions putting this in the opf file, but also mentions that Calibre will ignore this. Could I put this tag on each page to enable panel view?

Update: doesn't work. I added it a html page in the epub, converted it to azw3, confirmed that the meta is in the azw3, and still the page is not fullscreen.

kovidgoyal · 02-23-2015, 10:39 PM

Panel View is not dependent on markup, it requires modifications to MOBI file internals. It is not something I am interested in supporting, but patches are welcome.

If I were you, I'd just convert to PDF sized for my device. There is no advantage to using an ebook format for a comic/fixed layout book.

badbob001 · 02-24-2015, 12:59 PM

Thanks for the suggestion of PDF. It certainly makes the workflow easier than having to edit the original source EPUB and then figure out what changed and didn't change in the AZW3. One annoyance with PDF is that it may look weird from the computer (images not centered, every-other page is blank, HUGE margins), but it looks fine on the actual device. I wish amazon made a kindle emulator (I've tried the kindle previewer and it's not very accurate).

02-21-2015, 12:13 PM	#1
badbob001 Fanatic Posts: 556 Karma: 1102020 Join Date: Sep 2009 Device: Kindle Keyboard (rip), Kindle Voyage, Fire Tablet 10 '17, iPad '19	Enable kindle's auto-image upscaling in mobi? I have epub books that are about 99.9% images (eg: Diary of a Wimpy Kid) and when viewed as mobi on my Kindle Voyage, the images don't fill the screen and thus are too small to comfortably view. I suspect the images would look fine on a lower-resolution kindle but not on the voyage. I could long-press the image, click the magnifier to expand the image to fill the screen, but I have to do this for every page. When testing converting comics files using different apps (mangai or kcc), I've noticed that the kindle's mobi viewer will automatically crop out white margins and upscale images to fill the screen. I'm not sure if this only works for white margins in the actual image or if it would work with the white margins in the html page (which is the situation with the epubs), but this feature may help resolve my issue if there is a way to enable it. I think this is a feature of the mobi reader in the paperwhite as well. I don't know what special setting needs to be set in the mobi to enable this feature. When this is happening, the menu has these options: * Animation On/Off * Fit to Screen On/Off Note that I'm not aware of a way to DISABLE the automatic margin trimming/image upscaling for these documents. Otherwise, are there any other options in the conversion process to upscale these images, either by actually upscaling the images or some sort of width=100% html setting? In calibre, when I edit the epub, I see the html simply has each image in a separate <p> tag: Code: <p class="image"><a id="page_124"/><img alt="Image" src="../images/f0124-01.jpg"/></p> <p class="image"><a id="page_125"/><img alt="Image" src="../images/f0125-01.jpg"/></p> <p class="image"><a id="page_126"/><img alt="Image" src="../images/f0126-01.jpg"/></p> <p class="image"><a id="page_127"/><img alt="Image" src="../images/f0127-01.jpg"/></p>

02-23-2015, 06:06 PM	#3
badbob001 Fanatic Posts: 556 Karma: 1102020 Join Date: Sep 2009 Device: Kindle Keyboard (rip), Kindle Voyage, Fire Tablet 10 '17, iPad '19	I found a post about using this meta tag to set a book to comic-type: <meta name="book-type" content="comic"/> The post mentions putting this in the opf file, but also mentions that Calibre will ignore this. Could I put this tag on each page to enable panel view? Update: doesn't work. I added it a html page in the epub, converted it to azw3, confirmed that the meta is in the azw3, and still the page is not fullscreen. Last edited by badbob001; 02-23-2015 at 09:44 PM.

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02-23-2015, 04:56 PM	#2
badbob001 Fanatic Posts: 556 Karma: 1102020 Join Date: Sep 2009 Device: Kindle Keyboard (rip), Kindle Voyage, Fire Tablet 10 '17, iPad '19	I even tried switching from mobi to azw3 to see if perhaps something got lost in the conversion from epub due to the older mobi format. I'm guessing I need to enable "Panel View" for each page, but sadly I don't see that option for mobi/azw3 settings. How is that "enabled" physically in the ebook anyway? I spent some type looking at the css of the source epub, tried modifying the "image" class and was dumbfounded to why it didn't affect the image. Then I realized that the "image" class only affected the <p> tag. Now I can either add a "height=100%" to all of the <img> tags, add a "img" class to the css (may affect more images than intended), or create myself a new class (eg: class="imagepage"). But don't think I'm some css genius as I just use google for help on that and I'm basically a html 1.0 guy. It seems rather silly for ebooks to have a fixed-resolution mentality in their creation. I see options in Calibre to adjust text in the conversion, but really nothing for graphics. Maybe add some logic on when to modify a page to upscale image / enable Panel View? Like if the page no text but one large graphic?

02-23-2015, 10:39 PM	#4
kovidgoyal creator of calibre Posts: 43,866 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Panel View is not dependent on markup, it requires modifications to MOBI file internals. It is not something I am interested in supporting, but patches are welcome. If I were you, I'd just convert to PDF sized for my device. There is no advantage to using an ebook format for a comic/fixed layout book.

02-24-2015, 12:59 PM	#5
badbob001 Fanatic Posts: 556 Karma: 1102020 Join Date: Sep 2009 Device: Kindle Keyboard (rip), Kindle Voyage, Fire Tablet 10 '17, iPad '19	Thanks for the suggestion of PDF. It certainly makes the workflow easier than having to edit the original source EPUB and then figure out what changed and didn't change in the AZW3. One annoyance with PDF is that it may look weird from the computer (images not centered, every-other page is blank, HUGE margins), but it looks fine on the actual device. I wish amazon made a kindle emulator (I've tried the kindle previewer and it's not very accurate).

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