Low cover resolution in ePub

MartinM · 03-20-2018, 04:16 PM

Hi - I'm using Calibre to convert my .docx into ePub format for distribution. When I add a high resolution 2500 x 1600 (600dpi) JPG cover image to the file and convert to ePub the corresponding cover looks terrible in any reader I view in it, and the converted "cover.jpg" is shrunk and down to 96dpi. How can I improve the quality of the cover in the final ePub file?
Any advice will be great - thanks.

deback · 03-20-2018, 05:05 PM

Add or change the following in the class for the cover image in the .css file. Don't use "auto" for the cover image in both height and width.

height: 100%;
width: 100%;

davidfor · 03-20-2018, 06:02 PM

Quote:

Originally Posted by MartinM

Hi - I'm using Calibre to convert my .docx into ePub format for distribution. When I add a high resolution 2500 x 1600 (600dpi) JPG cover image to the file and convert to ePub the corresponding cover looks terrible in any reader I view in it, and the converted "cover.jpg" is shrunk and down to 96dpi. How can I improve the quality of the cover in the final ePub file?
Any advice will be great - thanks.

What output profile have you selected in the conversion? This sets the maximum size of the images and anything larger will be downscaled. If you don't want the covers resized, you probably should use the "Tablet" profile.

DoctorOhh · 03-20-2018, 09:23 PM

Quote:

Originally Posted by MartinM

Hi - I'm using Calibre to convert my .docx into ePub format for distribution. When I add a high resolution 2500 x 1600 (600dpi) JPG cover image to the file and convert to ePub the corresponding cover looks terrible in any reader I view in it, and the converted "cover.jpg" is shrunk and down to 96dpi. How can I improve the quality of the cover in the final ePub file?

To stop it from shrinking in Calibre go to Preferences - Tweak - The maximum width and height for covers saved in the calibre library change this tweak so maximum cover size is larger than the cover you are attempting to use. I have mine set to maximum_cover_size = (3000, 4000)

MartinM · 03-25-2018, 07:38 AM

Quote:

Originally Posted by davidfor

What output profile have you selected in the conversion? This sets the maximum size of the images and anything larger will be downscaled. If you don't want the covers resized, you probably should use the "Tablet" profile.

I was using the standard OUTPUT FORMAT "EPUB" setting that listed "Kindle" as the Output Profile.
When I switched to generic "TABLET" the cover wasn't resized - THANKS

03-20-2018, 04:16 PM	#1
MartinM Junior Member Posts: 5 Karma: 10 Join Date: Mar 2018 Device: kindle previewer	Low cover resolution in ePub Hi - I'm using Calibre to convert my .docx into ePub format for distribution. When I add a high resolution 2500 x 1600 (600dpi) JPG cover image to the file and convert to ePub the corresponding cover looks terrible in any reader I view in it, and the converted "cover.jpg" is shrunk and down to 96dpi. How can I improve the quality of the cover in the final ePub file? Any advice will be great - thanks.

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03-20-2018, 05:05 PM	#2
deback Book E d i t o r Posts: 432 Karma: 288184 Join Date: May 2015 Device: Laptop	Add or change the following in the class for the cover image in the .css file. Don't use "auto" for the cover image in both height and width. height: 100%; width: 100%;