Revert "* changed image format validation to extension validation (was failing for non-image formats)"
Revert "* changed image format validation to extension validation (was failing for non-image formats)"

This reverts commit d64df9f2979c00122ef67c442475935a4a491d10.

sinfin/folio,sinfin/folio,sinfin/folio,sinfin/folio