Mobileread
Smaller Epub is BIGGER in size than my longer one?
#1  Siegfried 02-23-2021, 02:48 AM
Hi,

I've looked for help on this online and can't seem to find something that works.

I've been making comics, and am trying to convert them into fixed-layout Epub formats. I made one a few months ago that's 84 comic pages, and managed to get the Epub to 21mb.

I now just made another one, using my old file as a template, but it's only 64 comic pages. However, for some reason, the Epub file size ends up at 29mb, which is far too large for my liking. I'd like to at least get it around the 20 mark (I feel it really should be smaller than my previous book, as it's shorter).

I've looked at the image sizes; they're approximately the same for both of my books. I've used online compressors, and even tried to "remove details and personal information" in the properties tab, but that made no difference (I assume the compressors did this already).

I looked at both books opened in Sigil, but can't seem to see much difference between them in either the sidebar or the html.

As a result, I really have no idea why the file size for this book is so much bigger than one I made before which is 20 pages longer.

I've attached a screenshot of what this Epub looks like when opened in Sigil. I already tried erasing the (one) style and font it had, which were unused, but the file size didn't change.

My earlier epub's folder containing its pages (in my file browser) is 100 mb, and this new epub's is 59 mb, so I'm having doubts it's because of the image sizes.

Is there some kind of "history" that's created when the ebook is made, as I keep using my earlier ones as templates for newer ones? I use Indesign to make my ebooks.

Thanks for any help in advance. Please let me know if any more details are required. I don't really know how to use Sigil, but have it installed for situations like this.
SigilScreenshot_Arc2.jpg 
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#2  exaltedwombat 02-23-2021, 08:15 AM
It's hard to imagine that the size of a graphical eBook isn't overwhelmingly about the total size of the image files. Go through the contents of the Images folder carefully.
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#3  KevinH 02-23-2021, 12:06 PM
In Tools you should see a Reports tool which should give you file sizes. Try the Files and/Or Images reports. Compare those sizes against the same for your longer epub.
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#4  fbrzvnrnd 02-23-2021, 01:56 PM
I need to see the two ePubs to tell you a fast answer. If you want sent a wetransfer with the 2 epubs (fabrizio(at)venerandi(dot)com)
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#5  Siegfried 02-24-2021, 12:28 AM
Thanks for the responses.

I got the reports for each Epub (had to zip them to upload it here, so do tell me whether or not they unzip ok). The file with the Number 1 in the filename is the book from months ago (84 pages, 21 mb), and the one with the Number 2 is the newer one (64 pages, 29 mb). If these don't provide enough information, I will just send the entire files across.

If it really is because of the image file sizes, as far as compressing goes, I don't quite see why the file sizes would be this much larger even after I'd compressed them. No compressors I've used can shrink these images down any more than they already have been.
[zip] WotN1_EpubReport.zip (1.4 KB, 25 views)
[zip] WotN2_EpubReport.zip (1.3 KB, 23 views)
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#6  Siegfried 02-24-2021, 12:58 AM
I just had a careful look at those reports myself, and compared them to the original image files. It seems some of them are converted to .png for some reason, despite ALL images originally being .jpg. These png files are the ones taking up most of the space.

Even in the earlier 21mb Epub, some images were converted to png, but not as many as in the newer one. I suspect this is what's making the file size so large. Is there a way to change them back to jpg through Sigil?

PS: Is it not possible to edit posts here? I couldn't find an Edit button anywhere. And I do apologise if this post appears twice, as I'd submitted it once and it didn't appear in the forum for some reason, so I'm posting it again.
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#7  DNSB 02-24-2021, 01:15 AM
Quote Siegfried
Thanks for the responses.

I got the reports for each Epub (had to zip them to upload it here, so do tell me whether or not they unzip ok). The file with the Number 1 in the filename is the book from months ago (84 pages, 21 mb), and the one with the Number 2 is the newer one (64 pages, 29 mb). If these don't provide enough information, I will just send the entire files across.

If it really is because of the image file sizes, as far as compressing goes, I don't quite see why the file sizes would be this much larger even after I'd compressed them. No compressors I've used can shrink these images down any more than they already have been.
Basically, looking at your reports, one file (N2) has 14 files over 1MB while the other (N1) has 7 files over 1MB. The total file size for over 1MB files in N1 is 9365.05KB while in N2, they total 18826.16KB. So there is pretty much the file size difference. Since most image formats are already compressed fairly well, it's hard to reduce the file size without losing quality.
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#8  Siegfried 02-24-2021, 01:24 AM
Yeah, I had a careful look at the reports myself in the last hour. It seems some of my images were converted to png for some reason (despite ALL sources being jpg). The png files seem to be the larger ones. No idea why they were changed like this.

Even in N1, some images were changed to png, but N2 seems to have suffered it worse, hence the larger file size.

Is there an easy way for me to change them back into jpg through Sigil?

On another note, both Ebooks are a similar total size when I made them PDFs.
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#9  fbrzvnrnd 02-24-2021, 02:15 AM
Quote Siegfried
Yeah, I had a careful look at the reports myself in the last hour. It seems some of my images were converted to png for some reason (despite ALL sources being jpg). The png files seem to be the larger ones. No idea why they were changed like this.

Even in N1, some images were changed to png, but N2 seems to have suffered it worse, hence the larger file size.

Is there an easy way for me to change them back into jpg through Sigil?

On another note, both Ebooks are a similar total size when I made them PDFs.
Are they color or BW comics? If BW you can open the PNGs and save those with a lower palette.
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#10  JSWolf 02-24-2021, 08:39 AM
One thing you can do for both eBooks is to load them into the Calibre editor and use the lossless compression to get rid of any excess data in the images. That won't change the compression level/quality. But it will make the file size smaller.
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