When exporting a .indd document as an epub the resulting file contains huge png files in size. These are colour boxes I have created - not images. Some up to 9000 x 4000. This is despite the document being 2300x1600.

You cannot upload the file for Apple iBooks because they have a limit on file dimensions of 4mb (ie: 2000x2000).

Please can you provide a way of reducing the file size of these .png colour blocks before export.

I am using In Design CC 2021 latest version (dated 29 July 2021).