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Old 07-10-2018, 11:15 AM   #1
un_pogaz
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Exclamation Calibre dont like 256 colors png cover

To reduce the size of my EPUB, I use Riot for optimize the picture of the book, especialy the cover.

I know that when integrating metadata Caliber my also updated the cover.
For JPG, okay.
But sometimes, a PNG cover, in 256 colors is more optimal without loss of quality (example with the attached image: Black and white, without or little gradation)
I optimize my image, put it manually in the book, then I update my metadata as well as the recorded size.
And I see that the size hasn't changed:
=> Caliber has reset the cover to TrueColors

(In the example image, the size increases from 226 KB to 95 KB)
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Old 07-10-2018, 12:18 PM   #2
kovidgoyal
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calibre stores covers in JPG format. JPG does not support indexed images. If you want to preserve the cover in your EPUB files you can either:

1) Turn off theEPUB metadata writer plugin in calibre, then EPUB metadata including covers will not be changed

2) Do not set a cover for the boo in calibre, then the in-book cover will be preserved
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Old 07-11-2018, 03:15 AM   #3
un_pogaz
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Quote:
Originally Posted by kovidgoyal View Post
calibre stores covers in JPG format. JPG does not support indexed images. If you want to preserve the cover in your EPUB files you can either:

1) Turn off theEPUB metadata writer plugin in calibre, then EPUB metadata including covers will not be changed

2) Do not set a cover for the boo in calibre, then the in-book cover will be preserved
1) I found something "Set EPUB metadata / Personalization : disable-add-missing-cover" but I don't think that's it.

2) What ???


Would it be possible to diversify the button "Integrated metadata" by adding 2 options ;
1) Integrated metadata without cover
2) Integrated the cover

For now, he does both at the same time and without distinction, which I find very foolish.
Added a separated function would resolve my problem easily, and would add finesse to Calibre.
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Old 07-11-2018, 03:33 AM   #4
kovidgoyal
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1) Disable the plugin entirely
or
2) Delete the cover from calibre, then calibre will not update the cover in the book

I'm afraid I'm not interested in adding a setting to only update non-cover metadata.
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Old 07-11-2018, 06:04 AM   #5
un_pogaz
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Delete the cover from calibre => Delete cover.jpg => No preview
...
I do not call that a solution.
The problem is avoided in an ugly and inelegant way.
Sure, with his methods: no need to solve a problem, there is not, since we all will do everything not to be confronted with it *whistle*.
*sigh*

By the way,
Thank for the answer and for taking the time to explain to me.
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Old 07-11-2018, 02:24 PM   #6
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Take a look to the plugin section. There you will find the PI ModifyEPUB.
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Old 07-12-2018, 02:43 AM   #7
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Quote:
Originally Posted by Divingduck View Post
Take a look to the plugin section. There you will find the PI ModifyEPUB.
Thank o/
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