Ask HN: Why are ePub images so tiny?
6 comments
Talking out of my ass, but since epubs often target mobile devices (kindle, kobo, etc - with limited storage) - publishers probably find that their books do better if they tend to be smaller in size. And images take up far more diskspace than text does in a digital copy.
Then when a user needs to delete books from a device they will start with the largest files. The longer the book is on the device the more likely they are to engage with it, etc.
Then when a user needs to delete books from a device they will start with the largest files. The longer the book is on the device the more likely they are to engage with it, etc.
Sorry, but this is nonsense. I'm not talking about photos, but about graphs, line art, tables. Using PNG you can create real small (in filesize) images, like 10-30 kilobytes. The size of the image (dimension) often doesn't matter that much. You can create the same image (black on white or line art with three or four colors) and resizing (less pixels) it won't make much of a difference in file size, nothing significant.
I cannot believe that publishers create small pictures because bigger pictures means that their book will be deleted later on. That argument seems far fetched.
I cannot believe that publishers create small pictures because bigger pictures means that their book will be deleted later on. That argument seems far fetched.
I did provide a warning of my nonsense. As you say though 10-30kb per image, in a 350+ page text book is already likely 7mb+ (assuming 1+ images pp). And that is absolute best case if the original images and optimization are working together. I would guess without any optimization for digital publication you could be starting from 100-200mb easily.
I imagine the images are scaled automatically based on the expected display resolution of the device and the size the image will be displayed at. If the encoder is set to assume a small kindle device, then this expected display resolution will be very small.
Epub is a wrapped HTML
The image sizes can be anything the creator wants.
If you look on some of the big free libraries, you will see that there are many different versions of popular books, all with different sizes.
The image sizes can be anything the creator wants.
If you look on some of the big free libraries, you will see that there are many different versions of popular books, all with different sizes.
I'm talking about books I have boought. I paid money for these books and expect some quality.
I wonder if anybody who creates these ebooks and the images ever reads them? Are these the same images as used in the paper books? My bet is that the images used for paper books are much higher quality, but I can't compare because in general I don't buy both the paper and epub version.
I've seen this in books from different publishers, different languages. Apparently it's a universal thing. Why? Can anybody explain?