[davidfor]

I'm embarrassed to say that I did not read the thread title properly. I assumed this was in the KoboTouchExtended driver thread. The points I originally mad mostly valid, and I'll leave them. I'll add the only other thing I can think of after them.

Originally Posted by koboyedi

Just one issue on kobo forma: graphics (e.g. cover pages) seem more compressed/distorted when using the plugin, expecially fonts that appear as graphics (e.g. title page right after the cover page). Is there a way to modify the compression level?

When do they look bad? In the book or when displayed as the cover image?

if it is the latter, you might want to try the options to send the cover. The driver generates the cover images directly from the covers in calibre and puts them on the device. Someone who cares about these images did some work last year to improve the quality.

If it is when reading, you need to check the actual code that is wrapping the image. Calibre will update the cover image in the book when sending it to the device. But, it needs to be able to find it, and it doesn't update the code that displays the cover. This means that if you had a low resolution cover in the book, and found a high resolution cover, it might not have been updated or the display options won't be optimal. Both of these can be fixed with the Polish books tool, the Modify ePub plugin, a conversion or using the editor.

Also, it could be the renderer. Epubs and kepubs use different renderers. They give different results when you see the image. The KoboTouchExtended driver doesn't actually touch the covers in the book. The only change it makes is to make sure the device can find the cover when it tries to generate the cover image.


Edit: This is where the output plugin stuff starts.


What output profile do you have? This is on the "Page setup" page of the conversion. The output profile sets the maximum size for images in the converted book. Anything larger will be scaled down. Anything smaller will not be changed. Don't use the Kobo profiles. I recommend using the "Tablet" option. That won't resize the images and will let the device handle them when you are reading. These are the only options that I can think of that affect the quality of the cover. You can change this each time you do a conversion, or via the preferences. That sets the defaults for new conversions.

As you are doing a conversion, the page should be setup correctly for the image size. Personally, for the cover options on the "KEPUB Output" page, I make sure the "No SVG cover" is unselected and select the "Preserve cover aspect ratio". To me those options will work best on my different readers.