Thumbnail Size

  1. 7 years ago


    When I click on analyze project it says that the thumbnails are 270MB which is more than the images and audio files combined. In the general settings area I clicked off "pages thumbnails with page number" but it didn't make a difference. I never created any thumbnails myself. Is there a location I can find these thumbnail files?

    Thank You!

  2. Pubcoder creates them for ease of reference. You can not modify them or eliminate them. They have nothing to do with page thumbnails.
    The new pubcoder 3 has a new compression algorithm. Hopefully this will compress the file size even greater.

  3. 6 years ago

    Thanks for responding. I understand. When I check my version of pubcoder it says version 2.5 and when I check for updates it says pubcoder is up to date. Is there another way to update to version 3?

  4. Angelo S

    21 Jul 2017 Administrator

    @Ignacio O Thanks for responding. I understand. When I check my version of pubcoder it says version 2.5 and when I check for updates it says pubcoder is up to date. Is there another way to update to version 3?

    Hello Ignacio, PubCoder 3 is available as a Beta version for Mac at the moment. This means that your 2.5 won't autoupdate until the final 3.0 is released. If you are using a Mac, you can grab PubCoder 3 Beta for Mac manually here

  5. 3 years ago

    Hi Angelo, I'm using Pubcoder 3.11 and still have this issue; the thumbnails in one project are 83MB. Kobo only allows upload of max file size 100MB, and these thumbnails put me way over the limit. Things I have tried:
    Analysed project; no orphaned thumbnails
    JPEG quality set to medium
    PNG compression enabled

    When I enabled PNG compression (the majority of my image files are png, and mostly transparent images, so I am not able to convert all to jpg), it only reduced the image total size by 1MB, but the thumbnail total file size didn't change at all. So I'm still well over 100MB for my total file size.

    Most of these png images are embedded in animation sequences. I have replaced some of these with video files as per your previous advice, and I could do this with the remaining pages. This would create other issues I would have to resolve for this project, but it would reduce the total file size of image assets. However, the thumbnails would still put the project over 100MB. So for now, there's no point me creating additional issues to resolve by using videos on every page instead of animations.

    Can you suggest anything else?

  6. Angelo S

    9 Nov 2020 Administrator

    Hello Kathryn,
    I believe you are speaking about stats in the "Analyze Project" window. Those stats refer to the project file itself, not the exports. When you export the project in EPUB, no page thumbnails are actually included.

    If you are curious about what is taking space inside your EPUB file, remember that an EPUB file is actually a ZIP file structured in a certain way, so you can change the extension of your EPUB file to .zip and expand it with your favorite unarchive utility, to see what's actually inside and what's taking up space.

    Best Regards,

  7. Thanks Angelo, I appreciate you checking in on this old thread! I tried changing the extension to .zip, but got this error message in Archive utility when trying to open. I'm using a Mac and this is the default unarchive utility.
    Unable to expand "My_New_Friend_(English_US)". It is an unsupported format.
    I'm curious, because the file size of the epub is 166.1MB. But in the Analyse Project Screen, the total of all files minus the thumbnails is only 107.7MB. So I'd like to see how that becomes 166.1MB when the project is rendered.

  8. Angelo S

    10 Nov 2020 Administrator

    On the mac, better to use "The Unarchiver" free utility.
    Again, the "Analyze Project" feature analyzes the project file, it has nothing to do with the exports. In the export, images are recompressed and sometimes rendered multiple times, e.g. when using the same image with different sizes. Usually the export is smaller than the project file but, again, you have to expand the EPUB to see what's actually taking up space.

  9. A dedicated epub unzip/zip utility is eCanCrusher. Works on both mac and windows. Just drop an epub on the program icon, and it will create a folder of files to inspect and edit. Dragging that folder on the program icon once more creates an epub.

    I am a new user of PubCoder, and I noticed that the compression of PNG files in PubCoder is not that great, so I use an external tool to recompress the files, and replace the old ones.

  10. thanks Angelo and Rayek, I've downloaded The Unarchiver and it worked no problem :-)
    Now to solve my issue of file sizes - it's the images. I will either have to follow Angelo's advice (best solution) and use videos instead of animations, or optimise the image files which sit in the animations before uploading them to my Pubcoder projects (probably still resulting in an exported book file which is over 100MB).
    Lesson for the day: listen to Angelo!

  11. Edited 3 years ago by Rayek E

    Hi Kathryn,

    I found PubCoder's PNG compression rather lacking and not very effective (but the same can be said of just about any other design software). I always use ColorQuantizer to optimize transparent assets (PNGs) which does a brilliant job.

    It is free, and in my opinion the best PNG optimizer out there. But unfortunately not available for Macs. Mac users have access to a reasonable effective optimizer in the shape of ImageOptim:

    You have two optional workflows:
    1) optimize the image assets before importing these into PubCoder (or replacing the existing ones with new optimized versions). Then ensure that for each image in the Selection tab --> Image Options the "Use Original Image" option is checked.

    This will instruct PubCoder to export the project with the original optimized assets intact.

    Alternatively 2) export your current project as-is, use the unarchiver tool to unzip all the epub files, and replace the images with optimized versions. Drag and drop all the images into ImageOptim, and have at it! Possible that the files sizes will be reduced quite a bit.

    As for the animations: one option is to replace your animations with APNG files. While PubCoder will not play these in the preview, as long as the Use Original Image option is used, these APNG files will play in Thorium reader (Windows/Mac/Linux) and the Apple reader.

    Here is a simple example. I took a small animation of a fox running consisting of 12 frames, and each frame is around 7~8kb at 153 by 139 px. The background is transparent, with some edge anti-aliasing. Thus, PNG is the only option here.

    Importing these in PubCoder and using the animation object to re-create the animation results in PubCoder saving new version at ~25kb per frame! That means Pubcoder increased the overall size of the originals from ~83kb to a whopping ~290kb!

    So I turned on the Zopfli PNG compression in the Project settings and exported once more (this is much slower, and only suggested for final testing and release versions). No difference, though.

    To tell PubCoder to use the original images, all assets used for the animations must be attached in the Assets panel. Then PubCoder will use the optimized versions.

    The full animation with separate frames then resulted in ~83kb. Not bad.

    Next, I converted the animation to an Animated PNG file. On a Mac you can use APNGb:
    On WIndows, APNG Assembler:

    The result: ~63kb. To import these APNG files in PubCoder, remamber to activate the Use Original Image option.

    Now, you must also understand that an APNG does not require any code to be run or added, which means you will save a bit on epub xhtml and css code as well. It means in overall probably around 20~25% smaller files. Also, don't forget that if elements are animated across the screen without seeing a static version, then the resolution of said asset can be reduced as well. Readers cannot focus well on moving objects, and we can get away with lower resolution assets, providing another opportunity to reduce file sizes.

    Movies are effective IF and WHEN no transpareny is required. Great for animated backgrounds, for example. But useless for transparent animated elements. (It is also possible to render the entire animation to a movie file, of course - but that would exclude any interactions. If your page is merely a static animation, converting the entire thing to a movie file is probably a good option depending on how much of the screen is animated.)

    My basic workflow consists of optimizing static PNG files with Color Quantizer, and importing those with the "Using original image" option activated for each. I do not rely on Pubcoder (or other design software) to prep my PNG images (or my JPG images, for that matter).

    For animations: it depends. While APNG is a good option, because these are non-lossy compressed frames, the resulting animation file size is quite heavy compared to movie files (which have lossy compression). So for full-screen background animations a movie file is the way to go.

    But for animated characters/foreground elements there are other options.

    1. APNG
    2. html5 driven animations

    Ideally (2) is used for larger characters, for example. Animate CC or Spine (two animation apps) can export to html. The approach here is to segment a character's limbs into parts that can be separately animated in an animation app. Then export an html5 version with a transparent background. The character parts are then compressed in a "texture atlas" (one image that contains all character parts).

    The animation files are then imported in PubCoder, and the html file placed in a smart object with an iframe tag.

    The main advantage here is that very complex animation sequences can be introduced, at little extra overhead, because only one or two texture atlasses will be used. This technique is often used in games as well, because the results speak for themselves, and the file sizes remain manageable.

    This option, however, is somewhat more complex to deal with, of course ;-)

    Sorry for the long write-up.


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