Thread: Stretch the cover to fit the screen?
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Old 06-29-2018, 10:44 PM   #21
davidfor
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Posts: 24,905
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Join Date: Jul 2011
Location: Sydney, Australia
Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos
Quote:
Originally Posted by jackie_w View Post
I seem to remember we had a short PM chat about this at the time I was experimenting.
It rings a bell now that you mention it.
Quote:
My observation is that whatever changes Kobo have made to image processing in the last 18 months, it has not cured the 'banding' on a GloHD screensaver.

I've attached a test epub you can play with if you want. It contains a cover full of smooth colour graduations.

The screensaver (sent as B&W, keep aspect ratio by calibre) on a GloHD is full of banding. The same book has a very smooth screensaver on a KA1. On an H2O it's not quite as smooth as the KA1 but it's still very good. The ClaraHD is very slightly better than the GloHD but still full of banding.

I transferred them all as kepub. When viewing the cover as page 1 of the kepub, rather than as a screensaver, the GloHD is much smoother, but still not as good as the KA1. The ClaraHD is smoother than the GloHD but not as good as the KA1.
I've done some experimenting, and I have to say the Glo HD is really bad. But, letting the device generate the cover image is fine. The device generated images are a lot larger than the calibre images. I'm sure this was OK at one point, but I don't usually send the covers. I'll have to experiment some more.
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