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Old 05-30-2020, 02:43 PM   #8
Tex2002ans
Wizard
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Posts: 2,306
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Join Date: Jul 2012
Device: Kobo Forma, Nook
Quote:
Originally Posted by Land_Outcast View Post
And for some reason I can't replicate the issue now, but it was showing weird behaviour (stretching the images vertically, turning the alpha into a zebra pattern or into a sort of grey transparency).
"Zebra pattern"? Like this?

https://www.mobileread.com/forums/at...7&d=1381013845
https://www.mobileread.com/forums/at...8&d=1381013878

That's my images from a topic in 2013:

"Sony Reader for PC -- not rendering 16-color png"

Are you saving your PNGs in a strange way?

Are you saving as Indexed? (Or the very obscure: "Indexed with Alpha"?)

What image editor are you using?

Quote:
Originally Posted by Land_Outcast View Post
Yes, I know, but an axe is an axe, gets the job done. Might be ugly and prehistoric, but it works.
GIF images are 256 colors max.

"Indexed PNGs" cover that entire use-case (256 colors).

Normal PNGs (Color + Color/Alpha) then take on the entire RGB color range.

On top of that, PNGs compress so much better, because it uses more modern algorithms.

Quote:
Originally Posted by Land_Outcast View Post
Of course I'd rather use the PNG, but I was (am) worried about file support (I'll try to replicate the weird behaviour and share it here).
There's no compatibility issues I know of besides the PNG->JPG conversion that sometimes happens through KindleGen.

Only has potential to get strange when you start going into the edge cases (like 4-bit Indexed PNG).

Note: Another thing you have to look out for is that lots of image editors sometimes embed tons of crap/metadata inside PNGs too. But that can easily be stripped.

Quote:
Originally Posted by Land_Outcast View Post
I'm attaching some samples of where I need to use transparencies.
If all else fails, just PNGs with white background (no Alpha).

Not ideal, yes. Potentially hideous on color backgrounds? Yes. Fully compatible? Yes! :P

And then you just save the transparent source for some future date (or a MobileRead-specific version where you don't have to care about sales).

Last edited by Tex2002ans; 05-30-2020 at 02:48 PM.
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