Formatting images in books

[alhawke]

My next fantasy book has a map. I use Vellum. I've got two formatting questions for any of you who've done images in books before.

Do you do anything special to keep the memory use down? In other words, any magic formula to keeping the image crisp but not using too much memory for the epub file? As you know, image memory leads to $. And if too high, it can force your book at a higher price due to Amazon TOC.

Any problems any of you have had transferring images in Vellum? (I haven't done it yet, but I removed a bio image once after having difficulty with transfer for Apple). I'd prefer to anticipate and deal with problems now than right before book release.

[Matthew]

Do you do anything special to keep the memory use down? In other words, any magic formula to keeping the image crisp but not using too much memory for the epub file?

Use a JPG image and play with the quality settings. For image clarity, I would not go below 60%. Typically I start with 80 or 90% and see how it looks. The higher the image resolution, the more impact a quality reduction will have in file size. This can be done with a free tool called GIMP ( https://www.gimp.org/ ) or Photoshop, or many others.

Here's a set of images with a width of 1024px for you to do see how the quality changes. I can do higher resolutions if you really need.

Quality	File Size	URL
100%	614 kb	https://matthews.world/imagecomparison/bg_1024_max.jpg
90%	89 kb	https://matthews.world/imagecomparison/bg_1024_90.jpg
80%	49 kb	https://matthews.world/imagecomparison/bg_1024_80.jpg
70%	36 kb	https://matthews.world/imagecomparison/bg_1024_70.jpg
60%	29 kb	https://matthews.world/imagecomparison/bg_1024_60.jpg

Notice the details start to "blur" together in blocks, and you start to see artifacts around edges with lower qualities. That said, look how insignificant the difference between 100% and 90% quality is compared to the file size savings.

[alhawke]

Very interesting. My eyes really see the difference at 100 vs 60. Thanks!