How to reduce size of image files?

[BetterRed]

Originally Posted by PeterT

You mean like this request?

Yes, something like that - I don't have much use for it, so I wont be doing anything to progress it.

A few months ago a friend showed me an ebook (mobi or AZW I think) which had about 20 colour 'plates', he said it was too big to read on his iPhone. I had a look at it via a convert to EPUB, the 20 odd plates were 8-12MB 35MP jpeg monsters that would gave looked great on a Sony 108" 4K screen. He declined my offered to 'fix'

BR

[HC9]

Hi all,
Here is an update of my case.

Fotosizer tests failed (both version)!

Now I am trying to really unzip epub files
- Unzip them all is ok
- In these conditions, resize images should not be a problem
- Repack epub data, as mentioned, should be done very carefully. If I zip all the files in one step, epub file is not correct. You have to do it in 2 steps.
So Easy to do it (2 steps) manually but I do not know how to do it in batch mode.

@BetterRed are you sure your epub file is correct?

Thanks in advance.

[PatNY]

Originally Posted by HC9

Fotosizer tests failed (both version)!

Failed at what? I'd be surprised if Fotosizer failed to do what it was designed to do -- easily and conveniently decrease the size of jpegs in batches at multiple compression levels.

Maybe it failed to do something you wanted it to do but it wasn't intended to do? That's a different matter.

Your needs are really exact and what you're looking for doesn't appear to be possible at this time with any available software.

--Pat

[BetterRed]

Originally Posted by HC9

Hi all,
Here is an update of my case.

Fotosizer tests failed (both version)!

Now I am trying to really unzip epub files
- Unzip them all is ok
- In these conditions, resize images should not be a problem
- Repack epub data, as mentioned, should be done very carefully. If I zip all the files in one step, epub file is not correct. You have to do it in 2 steps.

So Easy to do it (2 steps) manually but I do not know how to do it in batch mode.

I don't know how to do a two-step zip in WinRar - I selected folder in file manager, tapped 'w', selected Add to archive..., changed archive type to ZIP (my default is RAR), hit enter. renamed blah - blah.zip to blah_NEW - blah.epub, added that to library via Calibre Add Books.

Originally Posted by HC9

@BetterRed are you sure your epub file is correct?

I can read resultant EPUB with calibres' ebook-reader, and convert it to RTF and MOBI and read with Word 2007 and Kindle for PC

What I see in each case is what I see in the original EPUB and RTF & MOBI conversions from the original - my visual checks were limited - i.e. I did not do a forensic comparison. Also the images weren't embedded in wrap around text or anything fancy like that. So there maybe circumstances where unzipping & rezipping EPUBs causes problems.

There are some tools to verify the validity of an ePub, there's also the EPUB Quality Check plug in - I don't have any use for them, so I don't have them.

Of interest is that the EPUB with no images compressed a bit larger with WinRAR than the original

I agree with PatNY, Fotosizer works as advertised - it does not claim to do images resizes within a zip - nor does Photoshop or ACD or IrfanView or... The only consumer software I know of that does anything useful with images in a zip is MaxView e.g. browse, slideshow etc, i.e. its viewing features - but not its editing features.

Irfanview's Bulk processing facility will resize & recompress images in subdirectories, but I don't think it will save in situ if you use that feature. However it has an option to create a mirror directory tree in the designated "Results directory" - but it will only write the new images there - you would then have to copy those images into the unzipped epub folders (overwriting the originals).

BR

[HC9]

@PatNY
I tried to resize image with fotosizer inside a zip file seen as a folder by Windows.

@BetterRed
I tryed to directly zip the folder but the epub created was not correct (cover page was ko). I understood I have to create first a zip file with the mime element and after to add items of the ebook.


I contacted Govid Goyal !!
Here is our short talk

This is not worth the effort for me personally. If some one else wants
to implement it, I will be happy to supply any needed guidance. If so,
re-open the ticket and we can discuss it.

status wontfix

** Changed in: calibre
Status: New => Won't Fix

--
You received this bug notification because you are subscribed to the bug
report.
https://bugs.launchpad.net/bugs/1195271

Title:
[Enhancement] - Lower size of image files

Status in calibre: e-book management:
Won't Fix

Bug description:
Want to produce small ebook files
Best way is to create ebook files with optimized image files
To do so, we need to manage jpeg quality compression inside Calibre.
Can you do that ?
Best regards,

[BetterRed]

Originally Posted by HC9

@PatNY
I tried to resize image with fotosizer inside a zip file seen as a folder by Windows.

@BetterRed
I tryed to directly zip the folder but the epub created was not correct (cover page was ko). I understood I have to create first a zip file with the mime element and after to add items of the ebook.
[/I]

Aaaah, I think I know where you may have gone wrong. When you unzip the epub make sure that you extract it to a folder of the same name so that everything stays in its rightful place.

Lets say your epub file is MyBook.epub
Copy MyBook.epub to MyBook.zip
Rename MyBook.epub to MyBook_Original.epub
Unzip MyBook.zip to a folder named MyBook

The MyBook folder will have a file called mimetype that should contain the string application/epub+zip, otherwise I don't think its started out as an epub file.

Within the MyBook folder you must not

• delete any files,
• add any files,
• change any file or subfolder names
• move files around,
• change any text files (html, css, opf, ncx etc)

You should only resize the big image files and save them with exactly the same names in exactly the same places as you find them in the unzipped folder.

Watch out for things like .jpg files being saved as .jpeg or vice versa, also watch out for case changes - eg image.jpg becoming IMAGE.JPG, not sure case matters in this context - but its prudent to assume that it does.

Then zip the MyBook folder and rename it to epub - the original mimetype file will still be there.

You should end up with

file MyBook_Original.epub
file MyBook.zip
folder MyBook
file MyBook.epub

BR

PS : Re your communications with Kovid - If a "Shrink Images" feature was to be implemented I think its more likely to be done as an optional plugin, rather than within the core Calbre product - like Modify, Generate cover etc.

There's a sticky topic for Plugin Suggestions in the Plugins Subforum, you could pop something in there.

BR

[HC9]

Thanks for the answer and suggestion.
I just ask the question to the guy who created plug In [Size Cover].

[HC9]

Just a return from the guy who produced [size cover], no way to do it free.
It seems to be dead, now.