Image resize doesn't accept numeric input, sometimes

I’m working on a book with lots of vector graphic images. I’m trying to make sure that the images are all at 300dpi for printing. So I’m generating large images and scaling them down to the points I want in the document.

So, for example, I’ve got a 1680 x 428 px graphic. Inline, or linked, I get the option to resize the image. It notes that the image is 1680 x 428 pts at 72 dpi. So I type in a desired pt value of 102 pt for the height, and when I click in the width box it calculates 400 for the width and everything works just fine. This is great, lets me enter exactly the output size I want.

But if I want to make it smaller, I can’t enter the value, nothing happens, so if I type in 50 pt for the height. Nothing happens, it just freezes, can’t click anywhere else. I can use the slider to get it close to that, and it works, but it’s difficult to get the same number I want each time for a lot of similar images. And even after I slide it to say 48, and then try to hand edit it to 50, it won’t let me. (Is there a problem with trying to make a 300dpi image half size sometimes? So that it’s 600dpi?)

I’m using Sketch to generate the images, laying them out at about the size I want and then exporting them 4.2x to get at least 300 dpi for the images. But sometimes I want smaller versions, which is why I shrink them, which is where I run into difficulty.

(I’m open to any suggestions on best practices for this type of image, they look great for ePub, but in my experience on a previous book when I put it up on KDP for print, it didn’t like images less than 300dpi. I’ve got lots of these images (it’s a book about chords for ukulele, so tons of pictures of chord fingering diagrams) and have been wrestling with getting them sized right for both ePub and print.


Here’s one of the images with which I’m working.

This is down to a quirk of how the sliders have to have the same minimum and max values, which has a knock on effect to the values allowed in the text fields that are not quite the same. I’ll try to improve this for the next update. Thanks for the sample image, as that allows me to see the issue.

All the best,