How to not compress jpeg

Arrandir · 04-11-2020, 04:41 PM

I'm writing a handbook in photography, of course it will have lots of pictures which need high quality.
A draft is now formated in Sigil with HTML and the pictures are in the book. Unfortunately, the pictures had bad quality when I for he first time looked in the book with an ebook reader app. I checked the size of the epub-file which was one fifth of all the pictures together.
Is there a setting to prevent Sigil from compressing the pictures? If not, are there any alternatives?

KevinH · 04-11-2020, 04:46 PM

Sigil does not compress or process (lossy or lossless) images in any way. Perhaps you used calibre to create your ebook?

JSWolf · 04-11-2020, 04:49 PM

If you are using Adobe Digital Editions to check your eBook, that could be your problem with the graphics. ADE does a poor job of displaying images. Try using the Calibre viewer or some other program to view your eBook.

KevinH · 04-11-2020, 04:51 PM

An epub is by definition a zip archive. But that compression is lossless and is used on all files but the mimetype file. Lossless epub compression can not and does not impact image quality and as I said earlier Sigil does not process any images files in any way.

Perhaps your e-reader has a limitation?

Tex2002ans · 04-11-2020, 06:18 PM

Did you use some other program (Word/InDesign) to create the HTML?

What usually happens is the defaults in those programs are set to export low quality JPGs ("96 DPI") instead of the original images.

Arrandir · 04-11-2020, 07:43 PM

Thanks for quick replies. The problem was the app I used to read the book. Fullreader was terrible for pictures, but Pocketbook was much better.

04-11-2020, 04:41 PM	#1
Arrandir Junior Member Posts: 2 Karma: 10 Join Date: Apr 2020 Device: None	How to not compress jpeg I'm writing a handbook in photography, of course it will have lots of pictures which need high quality. A draft is now formated in Sigil with HTML and the pictures are in the book. Unfortunately, the pictures had bad quality when I for he first time looked in the book with an ebook reader app. I checked the size of the epub-file which was one fifth of all the pictures together. Is there a setting to prevent Sigil from compressing the pictures? If not, are there any alternatives?

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04-11-2020, 04:46 PM	#2
KevinH Sigil Developer Posts: 8,160 Karma: 5450818 Join Date: Nov 2009 Device: many	Sigil does not compress or process (lossy or lossless) images in any way. Perhaps you used calibre to create your ebook?

04-11-2020, 04:49 PM	#3
JSWolf Resident Curmudgeon Posts: 76,413 Karma: 136564696 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	If you are using Adobe Digital Editions to check your eBook, that could be your problem with the graphics. ADE does a poor job of displaying images. Try using the Calibre viewer or some other program to view your eBook.

04-11-2020, 04:51 PM	#4
KevinH Sigil Developer Posts: 8,160 Karma: 5450818 Join Date: Nov 2009 Device: many	An epub is by definition a zip archive. But that compression is lossless and is used on all files but the mimetype file. Lossless epub compression can not and does not impact image quality and as I said earlier Sigil does not process any images files in any way. Perhaps your e-reader has a limitation?

04-11-2020, 06:18 PM	#5
Tex2002ans Wizard Posts: 2,304 Karma: 12587727 Join Date: Jul 2012 Device: Kobo Forma, Nook	Did you use some other program (Word/InDesign) to create the HTML? What usually happens is the defaults in those programs are set to export low quality JPGs ("96 DPI") instead of the original images.

04-11-2020, 07:43 PM	#6
Arrandir Junior Member Posts: 2 Karma: 10 Join Date: Apr 2020 Device: None	Thanks for quick replies. The problem was the app I used to read the book. Fullreader was terrible for pictures, but Pocketbook was much better.