If you want to share the violations to the users not onboarded on Imagium, you can easily export the images in PDF format from home page.
Yes, PDF files can be easily compared as images.
Very minimal coding skills are required to use Imagium.
Imagium will always mark failure for images with different resolutions.
Imagium accepts images only in base64 format, so any format can be transformed to base64 first and then fed using API payloads. Refer here for more details.