Quote:
Originally Posted by Lemm
When I compare the output jpg files to the unpacked resources from the KFX (-u in the CLI), I notice more jpg compression artifacts and some distortion with images (like some lines looking more jagged and less vibrant when compared to the unpacked resources tiles or a full sized screenshot from the Kindle app). Is the output jpg quality compression something that could be adjusted higher or losslessly? Or is the quality being affected by the ePub 3 conversion happening in the middle? If so, would there be a way to lessen the compression that seems to be occurring on images in the epub conversion? It's just something that I've noticed when I zoom in on things while reading. Thank you!
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In most cases conversion to EPUB or CBZ by the plugin preserves the original image resources from KFX format. One situation where that is not possible is when KFX format contains a grid of tiles in place of a single image as sometimes occurs for high resolution images.
The current version of the plugin combines the tiles into a single JPEG image with approximately the same quality as the original tiles. That can lead to some slight degradation and artifacts. The next release of the plugin will instead produce a PNG image that will capture the content of the original tiles losslessly.
Another possible source of image changes is calibre itself. If you convert using the calibre conversion routine instead of the plugin CLI there can be rescaling of large images unless you set the Output Profile to Tablet.