More info: I determined that this problem occurs when image is:

– JPEG

– an ODD number of pixels wide

This seems related to ID's resizing bug/feature related to 72 ppi images with EVEN number of pixels, discussed here:

https://forums.adobe.com/messag…..04#1291804

It does indeed seem related to ID's use of the ID-generated 72 ppi proxy image instead of the original 72 ppi JPEG.

Hi Anne-Marie. Did your test use these settings in the ePub export:

– 72 dpi

– Image > Preserve Appearance from Layout?