We just added a new type of validation you can enforce on your asset fields (both single/multiple).
It's called "Image transformable by Imgix", and you can use it every time you want to make sure that the asset uploaded is in a format that Imgix can properly understand and apply transformation parameters to — ie. resize/crop/etc.
As of today, the main difference with the regular "Image" validation is that SVG files are not allowed as a format, as Imgix does not apply transformations parameters on them, but the general idea is that as Imgix supports new input formats, the validator will be updated to be always kept in sync.