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#1 |
Custom User Title
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Karma: 75337983
Join Date: Oct 2018
Location: Canada
Device: Kobo Libra H2O, formerly Aura HD
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Why does my Aura HD mess up the colours on my cover images?
While trying to troubleshoot what I thought was a Calibre issue, I found that using Kobo Utilities to delete all the covers and re-generating them on the device itself resulted in all the colours getting the RGB values swapped. (It took me a while to figure out because the Aura HD is eInk and thus in greyscale).
It doesn't happen when I upload the covers...guess I'll be doing that. But is this normal behaviour? ![]() |
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#2 |
Grand Sorcerer
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Karma: 47303824
Join Date: Jul 2011
Location: Sydney, Australia
Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos
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Did they look wrong on the device? Or did you only notice them because you looked at them using calibre?
I have seen this in the past. From memory, the covers displayed correctly, so I assumed the image handling was being done properly. |
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#3 |
BLAM!
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Karma: 26047202
Join Date: Jun 2010
Location: Paris, France
Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E
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The Kobo fb is indeed setup in BGR order, not RGB.
Code:
red: bitfield offset: 16, bitfield length: 8, MSB is right: no green: bitfield offset: 8, bitfield length: 8, MSB is right: no blue: bitfield offset: 0, bitfield length: 8, MSB is right: no alpha: bitfield offset: 24, bitfield length: 8, MSB is right: no Pixel format details: B: 0 / G: 1 / R: 2 / A: 3 (i.e., BGRA) Should alpha be honored? Yes. The point is entirely moot (outside of in-book content) once you've setup Calibre to handle the grayscaling on its own for covers thumbnails ![]() |
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#4 |
BLAM!
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Karma: 26047202
Join Date: Jun 2010
Location: Paris, France
Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E
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Which leads me to my next question: I'm actually pretty sure Kobo "fixed" it to actually make it consistent with what the framebuffer expects, so, *what* did you check, exactly?
(The generated files in .kobo_images? A Nickel screenshot? An fbgrab?). |
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#5 |
BLAM!
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Karma: 26047202
Join Date: Jun 2010
Location: Paris, France
Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E
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Okay, curiosity got the better of me.
ePubs: The covers are generated grayscale, with a crappy dithering pattern. KePubs: The covers are generated BGRA (which is good). And, what actually matters: Nickel itself grayscales everything now, so the point is doubly moot. |
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#6 | |
Custom User Title
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Karma: 75337983
Join Date: Oct 2018
Location: Canada
Device: Kobo Libra H2O, formerly Aura HD
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Quote:
I was looking at the cover in the device view of Calibre. |
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#7 |
BLAM!
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Karma: 26047202
Join Date: Jun 2010
Location: Paris, France
Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E
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Then everything's peachy, that's the way they ought to look for a Kobo
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