We have company-wide visual labels that correspond with our data classificaitons. In the Azure Information Protection portal, can you upload an image to be applied as the label or footer?
Seems no. You can apply a header, footer and/or a watermark, but there doesnt seem to be a way to use a picture with any of these. For now at least :)
You can leave feedback on the documentation page: https://docs.microsoft.com/en-us/information-protection/deploy-use/configure-policy-markings