Calibre 9.11 hashing cover in epub output?

[dpharshman]

I originally sent this to Calibre and they sent me over to Mobileread.


Hi,
I am publishing epubs, mostly for Barnes & Noble currently, running everything on the latest Win 10 Pro software.

As B&N’s epub conversion process has issues, I am trying a different method. Starting with an MS Word 2021 docx, using a B&N template,which contains the body of the book, I add a 300 dpi – 1865x2828 sized image for the front cover, then run the entire file through Calibre 9.11 to generate the epub file. Calibre's View function displays the epub, and the front cover still looks fine. Then after saving the book, I test the entire file using Adobe Digital Edition 4.5.12.112.

The problem is with the cover images (the title text is in large Castellar fonts). The covers are great with Paint Shop Pro and they appear perfect in Calibre. But, they uniformly come out hashed when the epub is tested with ADE 4.5. I have tried fiddling with various settings in Calibre but no joy (I believe all settings within Calibre were back to defaults before these files were generated). What am I missing? (Much smaller .jpg images in the body of the books come out fine, the cover, a key selling point for the books, is the main and constant issue.)

Per request attached are the following:

1. a fair copy of the front cover before conversion: front-cover-input.image.jpeg (from the debug/input folder)
2. the output version from Calibre, which also looks good, can be found by viewing: front_cover_processed_image.jpeg (from debug/processed folder)
3. but, when I open the epub using Adobe Digital it is hashed, see the screenshot entitled: Adobe-Digital-Editions-Screenshoot-2026-07-25_14-53-00.jpg
4. Or you can see the image by running the Lightning Strikes More Than Once - Volume 5 - eBook Test Sample - DP Harshman.epub with ADE V 4.5.12.112
5. Calibre's Conversion Log is also included

I need clean covers!!! HELP!
DP Harshman

[dpharshman]

The title has a typo, of course, should be Hashed.
And one of the upload files is missing: Adobe-Digital-Editions-Screenshot-2026-07-25_14-53-00 so you can see the results via the epub.

[dpharshman]

Updated. I made sure the ADE screenshot of the front cover attached properly so you can see the hashed results.

[DNSB]

What size do you have the maximum cover size set to? The cover in your sample epub is set to 1145x2200 while the original image is 1865x2838. I've attached an image from calibre ( Preferences => tweaks => maximum_cover_size) which you might want to set to something like my choice of 2500 x 3750 to keep your covers from being shrunk. I think the default is 1650x2200 which matches with your image resize.