Make the size from 200MB 400pp epub .. smaller? How?

hlk123 · 02-09-2018, 06:07 AM

Hello

I've an 400pp Epub ebook file .. 200 MB big.
Can I - with Calibre - make it smaller? How?
Thank you.

JSWolf · 02-09-2018, 06:18 AM

If you have embedded fonts, you can subset them and you can losslessly compress your graphics. That's about it.

Adoby · 02-09-2018, 07:03 AM

Another possibility is that the book contains a lot of very big images. Or is made up of just scanned images.

Before you start experimenting, make sure you have a backup of your book and library.

One way to handle this is to scale down the images. Easiest may be to change the output profile to something smaller than "tablet" (Preferences / Common Options / Page Setup) and convert the book from epub to epub.

The output profile "tablet" means that no scaling of images is done. Otherwise the images are scaled to suit the output profile selected. (Don't forget to change back to "tablet" or whatever you prefer when you are done.)

I have not tested this, perhaps you need to save the book to disk for the scaling to happen.

Another way is to simply open the epub and edit the contents. Scale images and remove fonts or videos and so on. And recompress as an epub. But this may be more complicated than the first method.

If the book is made up of a lot of scanned images then you should try to find another version where the images with text has been converted to actual text.

JSWolf · 02-09-2018, 07:06 AM

Do not lower the resolution of the images. You actually want hi-res images. Hi-Res eInk Readers need hi-res images. If you make them smaller, you could make less easy to see.

One other thing I just thought of is if you have any grayscale images, make sue that they are set to grayscale and not color. That might help.

Adoby · 02-09-2018, 07:20 AM

Sometimes the images are very important. And the book becomes unusable if they are scaled down. Then you may not want to scale them. Sometimes they are not very important at all. Then you can scale them. This was why I suggested you save a backup copy of the book...

In this case I suspect the book is scanned but not OCR:d.

I once had an 6MB epub with a huge cover image in PNG. The rest of the book was perhaps 150kB. I scaled down the cover to a more reasonable size, 1920x1080, and converted to jpeg and the whole book then was less than 300 kB.

dwig · 02-09-2018, 11:21 AM

Quote:

Originally Posted by Adoby

...
One way to handle this is to scale down the images. Easiest may be to change the output profile to something smaller than "tablet" (Preferences / Common Options / Page Setup) and convert the book from epub to epub.

The output profile "tablet" means that no scaling of images is done. Otherwise the images are scaled to suit the output profile selected. (Don't forget to change back to "tablet" or whatever you prefer when you are done.)
...

Good advice, but there's no need to make the change to Preferences.

There are two ways to make this change:

1. Make the change in the "Page Setup" section of the conversions dialog. This makes the change for this conversion and for future conversions of this one book until another change is made.

2. Make the change in Preferences to change the default setting for all future conversions of all new books.

You should make the change to Preferences if, and only if, this is a universal choice that you wish to make. If you are wanting to resolve an issue with one particular book then make the change in the Conversion dialog.

Adoby · 02-09-2018, 11:25 AM

Good point!

fidvo · 02-09-2018, 11:30 AM

200 MB suggests you have a lot more in the book than text. As others have mentioned, maybe the book is made up of pictures of text, in which case there might not be much you can do about it short of running it through an OCR program and fixing the errors by hand.

Personally the first thing I would do is unzip the file to look at what's stored inside. Epub books are actually zip files. You can then identify what's taking up the most room. If you're really lucky, it's something not actually important to the book, and you can fix the problem by deleting it in Calibre's editor or another tool.

If you can get more detail on the problem this way, we might be able to give you more specific advice.

hlk123 · 02-09-2018, 12:35 PM

Hello

I didn't know that xyz.EPUB = xyz.ZIP

The original ebook is a 200 MB mobi ebook .. searchable and with 400 images .. each 500 kB. big.
For my Android Nexus7 I need a PDF ebook with a TOC bookmarks.

At the end .. after converting and optimizing .. I get a 15 MB PDF ebook .. searchable & with pictures.

Converting .. with Calibre:
200 MB mobi -> 80 MB PDF

Optimizing .. with PDF-XChangeEditor:
80 MB -> 15 MB optimized PDF.
plus a handmade TOC bookmarks.

BTW .. the pictures size is "normal" & good.

Thank you ..

JSWolf · 02-09-2018, 04:40 PM

Quote:

Originally Posted by Adoby

I once had an 6MB epub with a huge cover image in PNG. The rest of the book was perhaps 150kB. I scaled down the cover to a more reasonable size, 1920x1080, and converted to jpeg and the whole book then was less than 300 kB.

Covers these days should be 1600 lines minimum.

02-09-2018, 06:07 AM	#1
hlk123 Enthusiast Posts: 44 Karma: 10 Join Date: Jan 2013 Device: Nexus7(2013), KindleFireHD7, PB622, PB623, AsusMemoTabHD7	Make the size from 200MB 400pp epub .. smaller? How? Hello I've an 400pp Epub ebook file .. 200 MB big. Can I - with Calibre - make it smaller? How? Thank you.

02-09-2018, 07:03 AM	#3
Adoby Handy Elephant Posts: 1,736 Karma: 26785668 Join Date: Dec 2009 Location: Southern Sweden, far out in the quiet woods Device: Thinkpad E595, Ubuntu Mate, Huawei Mediapad 5, Bouye Likebook Plus	Another possibility is that the book contains a lot of very big images. Or is made up of just scanned images. Before you start experimenting, make sure you have a backup of your book and library. One way to handle this is to scale down the images. Easiest may be to change the output profile to something smaller than "tablet" (Preferences / Common Options / Page Setup) and convert the book from epub to epub. The output profile "tablet" means that no scaling of images is done. Otherwise the images are scaled to suit the output profile selected. (Don't forget to change back to "tablet" or whatever you prefer when you are done.) I have not tested this, perhaps you need to save the book to disk for the scaling to happen. Another way is to simply open the epub and edit the contents. Scale images and remove fonts or videos and so on. And recompress as an epub. But this may be more complicated than the first method. If the book is made up of a lot of scanned images then you should try to find another version where the images with text has been converted to actual text. Last edited by Adoby; 02-09-2018 at 07:07 AM.

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02-09-2018, 06:18 AM	#2
JSWolf Resident Curmudgeon Posts: 73,975 Karma: 128903378 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	If you have embedded fonts, you can subset them and you can losslessly compress your graphics. That's about it.

02-09-2018, 07:06 AM	#4
JSWolf Resident Curmudgeon Posts: 73,975 Karma: 128903378 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	Do not lower the resolution of the images. You actually want hi-res images. Hi-Res eInk Readers need hi-res images. If you make them smaller, you could make less easy to see. One other thing I just thought of is if you have any grayscale images, make sue that they are set to grayscale and not color. That might help.

02-09-2018, 07:20 AM	#5
Adoby Handy Elephant Posts: 1,736 Karma: 26785668 Join Date: Dec 2009 Location: Southern Sweden, far out in the quiet woods Device: Thinkpad E595, Ubuntu Mate, Huawei Mediapad 5, Bouye Likebook Plus	Sometimes the images are very important. And the book becomes unusable if they are scaled down. Then you may not want to scale them. Sometimes they are not very important at all. Then you can scale them. This was why I suggested you save a backup copy of the book... In this case I suspect the book is scanned but not OCR:d. I once had an 6MB epub with a huge cover image in PNG. The rest of the book was perhaps 150kB. I scaled down the cover to a more reasonable size, 1920x1080, and converted to jpeg and the whole book then was less than 300 kB.

02-09-2018, 11:25 AM	#7
Adoby Handy Elephant Posts: 1,736 Karma: 26785668 Join Date: Dec 2009 Location: Southern Sweden, far out in the quiet woods Device: Thinkpad E595, Ubuntu Mate, Huawei Mediapad 5, Bouye Likebook Plus	Good point!

02-09-2018, 11:30 AM	#8
fidvo Addict Posts: 296 Karma: 1599870 Join Date: Jun 2012 Device: none	200 MB suggests you have a lot more in the book than text. As others have mentioned, maybe the book is made up of pictures of text, in which case there might not be much you can do about it short of running it through an OCR program and fixing the errors by hand. Personally the first thing I would do is unzip the file to look at what's stored inside. Epub books are actually zip files. You can then identify what's taking up the most room. If you're really lucky, it's something not actually important to the book, and you can fix the problem by deleting it in Calibre's editor or another tool. If you can get more detail on the problem this way, we might be able to give you more specific advice.

02-09-2018, 12:35 PM	#9
hlk123 Enthusiast Posts: 44 Karma: 10 Join Date: Jan 2013 Device: Nexus7(2013), KindleFireHD7, PB622, PB623, AsusMemoTabHD7	Hello I didn't know that xyz.EPUB = xyz.ZIP The original ebook is a 200 MB mobi ebook .. searchable and with 400 images .. each 500 kB. big. For my Android Nexus7 I need a PDF ebook with a TOC bookmarks. At the end .. after converting and optimizing .. I get a 15 MB PDF ebook .. searchable & with pictures. Converting .. with Calibre: 200 MB mobi -> 80 MB PDF Optimizing .. with PDF-XChangeEditor: 80 MB -> 15 MB optimized PDF. plus a handmade TOC bookmarks. BTW .. the pictures size is "normal" & good. Thank you ..