[Conversion Plugin] KFX Input

[jhowell]

Originally Posted by tomsem

I am noticing that PDF's generated from comic book format with From KFX (converted from KPF) have inflated page dimensions.

For example, given 1238 x 1800 images in original artwork, the page dimensions in the PDF wind up as 17.19 x 25 inches, as if the images had 72 PPI property. In this case 300 PPI would derive 4.13 x 6 inches, which is the physical page size of the printed comic.

The plugin does not currently set the DPI when creating PDF pages. It appears that the default value is 72 for the PDF creation software it uses.

Amazon comic format does not specify actual page sizes since that is not generally relavant for an e-reader. However the underlying image files may sometimes have DPI metadata. I will change plugin to use that when available and otherwise default to 300 dpi.

How that works out will depend on whether or not the underlying images contain reasonable DPI values. I will do some testing before releasing the change.

[tomsem]

Originally Posted by jhowell

The plugin does not currently set the DPI when creating PDF pages. It appears that the default value is 72 for the PDF creation software it uses.

Amazon comic format does not specify actual page sizes since that is not generally relavant for an e-reader. However the underlying image files may sometimes have DPI metadata. I will change plugin to use that when available and otherwise default to 300 dpi.

How that works out will depend on whether or not the underlying images contain reasonable DPI values. I will do some testing before releasing the change.

In my spot checking, the image DPI does not seem to matter (when I import folder of image files to Kindle Create).

When importing PDF to KC, image objects therein do not have DPI property, and I assume KC is assigning one when it imports these.

Before importing PDF to KC, I take care that the page sizes are accurate so that KC doesn't scale the images up (as recounted earlier in this thread).

[jhowell]

Originally Posted by jhowell

Amazon comic format does not specify actual page sizes since that is not generally relavant for an e-reader. However the underlying image files may sometimes have DPI metadata. I will change plugin to use that when available and otherwise default to 300 dpi.

How that works out will depend on whether or not the underlying images contain reasonable DPI values. I will do some testing before releasing the change.

I have done some testing and the DPI values found in the images in Kindle books are all over the place and not useful. Also, using a fixed value of 300 DPI is good for many books but works poorly for others.

I am now planning on having the code choose from a small set of common DPI the value that results in page sizes in the range of a typical textbook or comic.

[tomsem]

That seems like a good approach.

On lower bound, 4.12 x 6 inches is smallest I've seen (for manga that are supposed to fit in a pocket).

On upper bound, 7.5 x 10.5 inches is larger than any I've checked.

However, some of the HB PDFs had double size pages (double width) mixed in. So perhaps only vertical dimension should be considered when determining what is in range.

[Bluejinx]

Bug Report: "page_template has extra data" error (Japanese Fixed-layout KFX)

I have encountered a conversion error with certain Japanese fixed-layout KFX books (comics). The conversion fails due to unexpected data in the page_template section.

The behavior differs between the CLI and the GUI:

• CLI (calibre-debug -r "KFX Input"): It reports the error but continues and successfully creates a functional EPUB file.
  
  Calibre GUI (Standard Conversion): It raises an Exception and the conversion fails entirely.
  

Environment:

• Calibre: 8.16.2
  
  KFX Input Plugin: 2.28.0
  
  OS: Windows 11
  
  BOOK ASIN: B0D8SPYCRH , B0D3TCKTRY
  

Error Message:

ERROR: Section [ID] page_template has extra data: {$434: $441}

Logs:

(Note: Personal paths and user names have been masked with <USER> and <PATH>.)

1. CLI Execution (Succeeded with error)

PS <PATH>> calibre-debug -r "KFX Input" -- -e "C:<PATH>\high.kfx" "C:<PATH>\output.epub"

...

Software versions: KFX Input 2.28.0, calibre 8.16.2, Windows-10-10.0.22631-SP0

...

Metadata: ASIN=B0D8SPYCRH, asset_id=CR!9JBQ9ZFWKX47XFZSSR1VZPMPSD8A, ..., yj_fixed_layout=1

Converting C:<PATH>\high.kfx to EPUB

Converting book to EPUB 3

ERROR: Section c7T page_template has extra data: {$434: $441}

Format is fixed layout comic

Conflicting viewport aspect ratios: 34 @ 0.715052 (2000w x 2797h), 1 @ 1.163467 (2000w x 1719h), 1 @ 0.935454 (2000w x 2138h)

Converted book saved to C:<PATH>\output.epub

2. Calibre GUI/Normal Conversion (Failed with Exception)

InputFormatPlugin: KFX Input running

on C:\Users<USER>\AppData\Local\Temp\calibre-utr6a_ff\dtzrva4c.kfx

...

Metadata: ASIN=B0D3TCKTRY, asset_id=CR!VZCSJ935852C9510AKHYPPWVQHKX, ..., yj_fixed_layout=1

WARNING: This book has a layout that is incompatible with calibre conversion.

Converting book to EPUB 3

ERROR: Section c9E page_template has extra data: {$434: $441}

Format is fixed layout comic

Traceback (most recent call last):

File "calibre_plugins.kfx_input.init", line 113, in convert

Exception: Section c9E page_template has extra data: {$434: $441}

During handling of the above exception, another exception occurred:

...

calibre.ebooks.conversion.ConversionUserFeedBack: {"msg": "Cannot convert...", "level": "error"}

Thank you for developing and maintaining this indispensable plugin. I would appreciate it if you could look into this when you have time.

Since I can successfully convert these books using the CLI, this is not an urgent issue for me. Please feel free to prioritize this at your convenience. Thank you again for your hard work!

[jhowell]

Originally Posted by tomsem

On lower bound, 4.12 x 6 inches is smallest I've seen (for manga that are supposed to fit in a pocket).

On upper bound, 7.5 x 10.5 inches is larger than any I've checked.

However, some of the HB PDFs had double size pages (double width) mixed in. So perhaps only vertical dimension should be considered when determining what is in range.

Thanks for the info.

I plan to select a DPI from a limited set that yields a height closest to 9.5 inches.

[jhowell]

Originally Posted by Bluejinx

Thank you for developing and maintaining this indispensable plugin. I would appreciate it if you could look into this when you have time.

That book has a formatting variation that I have not yet seen. I will try to duplicate the problem using manga that are available to me at Amazon US. I may need further information from you if I am unable to do so.

[jhowell]

Originally Posted by Bluejinx

Thank you for developing and maintaining this indispensable plugin. I would appreciate it if you could look into this when you have time.

Originally Posted by jhowell

That book has a formatting variation that I have not yet seen. I will try to duplicate the problem using manga that are available to me at Amazon US. I may need further information from you if I am unable to do so.

Unfortunately I was unable to find a manga that exhibits this problem. There is something you could do to help.

Since you are already familiar with the CLI of this plugin, you can use it again with the "--unpack" option. That will generate a .zip file. Inside that .zip there will be a file named book.ion. For a comic/manga that file contains only the formatting information for the book without the copyrighted images.

If you could post it to this forum that would be very useful in diagnosing the problem. (You may need to create a new .zip file containing only book.ion in order to post it here.) Thanks.

[Bluejinx]

Originally Posted by jhowell

If you could post it to this forum that would be very useful in diagnosing the problem. (You may need to create a new .zip file containing only book.ion in order to post it here.) Thanks.

Thanks for looking into this.

Following your advice, I have extracted the formatting information using the unpack option. I have attached a zip file that includes the book.ion files for two separate books.

Please let me know if you need anything else.

[jhowell]

Originally Posted by Bluejinx

Following your advice, I have extracted the formatting information using the unpack option. I have attached a zip file that includes the book.ion files for two separate books.

Thank you for doing that. I was able to see the formatting being used for a page spread in each of those books that I had not encountered before.

I will release an updated version of the plugin once I do more testing to see whether the fix causes any new problems.

[jhowell]

Version 2.29.0 - 30 Jan 2026

Handle books with the vertical-align property present in a table colgroup. (Fixes error "Unexpected style definition: $478: True")

Handle formatting of page spreads seen in some Japanese manga. (Fixes error "Section xxx page_template has extra data: {$434: $441}")

Generate more reasonable page sizes when producing PDFs from high resolution images.