Images on an external server

[pepperop]

Hi,

My project is to 'convert' a physical book into an e-book by making use of Sigil
The book contains 380 pages (A4) and approx. 475 (color)pictures.

The booktext is now about 6 Mb. The images are consuming 70 Mb.

The idea is to store the images on a cloud location like Google Drive.

My knowledge of the HTML/CSS syntax is to little to write it in a codepage. Can you give me a suggestion or a solution how to manage this issue.

Looking forward your reply!

Pepperop

[Turtle91]

First off, welcome to MR!

Let’s break down your question a little bit.
- 375 pages of text shouldn’t be anywhere close to 6MB of data. I think you may have a huge amount of code bloat (unneeded html/css). I would expect a book that size to be about .5MB. For comparison, I am combining all 3 of the Lord of the Rings into a single file and the text only is about 1.5MB.

- the whole point of an ePub is that it is a self contained file… it has everything it needs (text, images, font, styling, etc.) in one location so it can be read anywhere. Think about the individual that is reading the book while on a boat/airplane, or in the mountains, or after a weather induced power outage, and they don’t have Wi-Fi. Trying to read a book like that would cause them to report your book as 'broken'… not to mention just giving them a bad experience.
I would recommend processing the images so that they are the smallest file size you can get while still maintaining clarity. Different file types do much better than others depending on the type of image (.png, .svg, .jpg) are commonly supported.
If you still have a file size that is too large you can consider breaking the file down into smaller sections/divisions/volumes.

- if you really must go down the path of external resources then, assuming the server is maintained forever (domain name/address is maintained) and the data isn’t archived, you can reference an external source with the proper html link. This question has been asked a few times so just try a search of the forum.
The short answer is just to give the proper location of the image in the <a> tag. Here is a quick tutorial on hyperlinks.
Example:
<a alt="mountain scene of lake in valley" src="yourserverdomainname/yourfolder/yourimage.jpg"/>

[Quoth]

Shorter answer.
Never have anything external.

Some ereaders don't have internet/wifi/mobi and some users keep the device in airplane mode.
Also no such thing as always available internet everywhere.

The idea is to store the images on a cloud location like Google Drive.

Only works for web sites. A totally broken idea for anything else.

[Turtle91]

I’ve also seen people use images for a particular font (re the LotR runes). If that applies to you then I would see about finding, or creating, your own font to replace those images. As with any solution, there are drawbacks to this idea… eg. some devices don’t honor embedded fonts… so check your target device/market to see if that is an option.

Cheers!

[KevinH]

The epub3 spec does allow external resources with the proper opf manifest properties set but I think that only applies to audio and video resources.

So pre-processing the images to reduce the file sizes without losing clarity should be your first step.

[pepperop]

@Turtle91 & @KevinH
Thank you for your comment. For me it is clear to invest more time/effort to 'clean-up' the epub itself.
The ebook-text is consuming only 5,7 Mb., the images 65 Mb. So a serious clean-up is essential. First I will check -again- the option to minimize the images instead to look for external partners or methods.

[JSWolf]

Originally Posted by pepperop

@Turtle91 & @KevinH
Thank you for your comment. For me it is clear to invest more time/effort to 'clean-up' the epub itself.
The ebook-text is consuming only 5,7 Mb., the images 65 Mb. So a serious clean-up is essential. First I will check -again- the option to minimize the images instead to look for external partners or methods.

One thing to know. The images should be hi-res. eInk Readers are 300DPI and hi-res. SO if the images are too small, they could be hard to see details. The Kobo Libra 2 is 1264 x 1680 and the Kindle PW5 is 1236 x 1648. Those are two of the more common Readers.

[Turtle91]

What JSWolf mentions is true about the screen size/resolution...Just a little clarification, you are not required to fill the whole screen. Just make sure your images still look good/acceptable with the higher resolution screens. A small (300x500 pixels) image at "72DPI" (although DPI is a printer resolution, not truly a screen resolution) shown on an 8cm wide screen at 300DPI would look incredibly small.

Also, make sure you are testing it on your target devices/readers. If you are not selling on the Kobo or Kindle market then there is no need to cater to their peculiarities. Having said that, you'd be cutting yourself out of a HUGE market share if you didn't sell there!

Cheers,

[pepperop]

So the art of 'tuning' is to have hi-res Images. That means that I have to resize most of the pictures (e.g. max. 3x5 cm each). A new challenge! What can be a good and opensource tool to do this job for creating a good result for my book? Is there a 'standard' in the world of ebook creators?

[Turtle91]

That’s a rather personal question!!! lol

Seriously though, it pretty much boils down to what you like and are comfortable using. I stay away from ‘online’ programs for security reasons. You lose control of your image the second you upload it… not good if there are any copyright issues.

There are some good open source programs such as GIMP and Inkscape. There are definitely other programs that are more specialized for those limited uses. Others here might have more recommendations. In general though, it boils down to what you have and what you know how to use.

I personally use Photoshop for 95% of the work, and Inkscape for .svg files. Adobe’s prescription model for their entire package of software is useful and not too unreasonably priced.

Edit: I forgot to mention Affinity. It is a VERY reasonably priced software that you can buy without locking yourself into a prescription. Their suite of software is fully featured and very professional.

[KevinH]

One other good tool useful for command line batch image processing is the open source package ImageMajik which runs on all platforms. I often resort to it to batch process tens to hundreds of images in a similar manner. Another useful tool in your arsenal.

And if you are good with python, the PIL package (new fork) can be easily programmed to batch process images as well.

[pepperop]

Thank you all for this college tour. The lesson I learned is to invest more time to 'reorganize' the elements of the book myself instead to search for external tools without knowing if the continuity will be stable in the (near) future.
Hopefully my bookproject can be realized soon ... with your advices!