Optimal image size, resolution and format

[John123]

Hi All,

I'm now getting quite a lot of interest in doing illustrated books. I've searched the forums and couldn't find any threads on this topic, please forgive me if there is, I simply didn't see it.

Trying to be all things to all persons (PC or what? ), or, in other words, all things to all flavours of ebook readers (hardware that is), is there an optimal size, resolution and format, I can make my illustrations using photoshop? The format would probably be PNG, but I'm open to other suggestions.

I guess on an iPad it would be better to get the highest possible resolution for, say, a technical illustration so it can be enlarged for the reader to study and keep it legible. But on a run-of-the-mill image of a portrait or a landscape, where the image is just to enhance the text where it doesn't need to be enlarged and the end-user screen is the limiting factor.

I'm trying to be as economical as possible with file sizes at reasonable proportions. The illustrations will be in colour.

Thanks in advance,

John.

[DiapDealer]

I'm usually one to encourage some pretty liberal stretching of the "related to Sigil" rules in these forums, but man... you didn't even use the word Sigil anywhere in this post. You gotta toss someone even the tiniest Sigil/ePub relevance bone, here.

[Ripplinger]

This thread might get you started. Do all ereaders handle png images ok now? I thought they mostly stuck to jpg, gif and maybe bmp?
https://www.mobileread.com/forums/sho...d.php?t=195778

[DSpider]

They should. It's part of the ePub spec. Kindles obviously do; they even recommend it for the cover.

[John123]

Originally Posted by DiapDealer

I'm usually one to encourage some pretty liberal stretching of the "related to Sigil" rules in these forums, but man... you didn't even use the word Sigil anywhere in this post. You gotta toss someone even the tiniest Sigil/ePub relevance bone, here.

Hi, I must apologise. I'm using Sigil and epub to produce all my ebooks and just didn't think of making any reference to it/them. Will try and remember next time.

[John123]

Originally Posted by Ripplinger

This thread might get you started. Do all ereaders handle png images ok now? I thought they mostly stuck to jpg, gif and maybe bmp?
https://www.mobileread.com/forums/sho...d.php?t=195778

OMG, what a can of worms. It would seem there are no definitive standards, then. With soooo many e-readers how could there be and where will it end? I just saw the first 8k telly on the news this morning!!!!

Cheers, job done.

[DaleDe]

Originally Posted by John123

OMG, what a can of worms. It would seem there are no definitive standards, then. With soooo many e-readers how could there be and where will it end? I just saw the first 8k telly on the news this morning!!!!

Cheers, job done.

There are standards however, some eReaders don't fully follow them and some eReaders extend them. For example the standard does not define BMP files as standard however, many Windows eReaders support them since they are based on Windows API stuff which automatically has BMP support.

It is a can of worms but it is a small can. 90% of the stuff is ok in almost all readers but there are a few Gotchas. The basis for ePub is HTML files and thus many eReaders use code from browsers as a starting point and end up with browser behaviors instead of ePub behaviors from time to time. The de facto standard reader is from Adobe, called Adobe Digital Editions, as they offer an API for sale to eBook Reader makers and have a DRM scheme that is also used by many customers including Public Libraries. Please check our wiki for terms you don't understand.

Dale