I added the mimeTypes as " images/png, images/gif" etc.. in crdxe. But once i upload and edit, i cant view the preview in dialog box. So i analyse the render.jsp file coming under /libs/cq/gui/components/authoring/dialog/fileupload and what i understood is that the issue occurred from hasImageMimeType and hasVideoMimeType declaration.
I changed the array list from Arrays.asList(mimeTypes).contains("image"); to Arrays.asList(mimeTypes).toString().indexOf("image"); and its working. Could you please check is this relevant one or any property declaration issue.