A journal cover has to be an image file under 15 MB. There is no dedicated crop tool, so UNI recommends 2000 x 1500 pixels (a 4:3 ratio) as a size that will sit well in the space, but nothing on the page enforces that dimension. And there is no Remove button anywhere in the editor: the only way to take a cover off a journal is to upload a different image over it.
The file has to be an image, and under 15 MB
Two checks run the moment you pick a file, before anything is sent to UNI:
- File type. If what you selected is not an image, the upload stops with "Please select an image file."
- File size. Anything at or over 15 MB stops with "File size must be less than 15 MB."
Both are dead simple pass or fail checks. There is no compression step and no retry with a smaller version offered automatically. If your file trips either one, fix the file (convert it, or export it smaller) and pick it again.
2000 x 1500 is a recommendation, not a rule
The uploader shows "Recommended: 2000 x 1500 px (4:3 ratio)" as a hint, but nothing in the upload path measures the width or height of what you send. A 400 x 300 image and a 6000 x 2000 image both pass the same two checks above and both get accepted. The recommendation exists because the cover space is built around that ratio, so images shot to a different proportion will get cropped by the layout rather than by anything you control at upload time.
Uploading needs a saved draft, not just an open editor
If you try to add a cover before your journal has a title, the upload is refused with "Please add a title to create your journal before uploading a cover image." A journal only gets the internal record a cover image attaches to once you have given it a title, so on a brand new journal, title first, cover second. Once the title exists and the draft is saved, the same uploader accepts a file normally.
There is no Remove, because there is nothing on the backend to remove it with
Once a cover is on a journal, the editor gives you no control to take it off again. That is not a missing button so much as a missing endpoint: the service that receives a cover upload only accepts new images, and does not accept a request to clear the field. The editor's own upload settings reflect this directly, deletion is switched off rather than merely hidden.
In practice this means a journal cannot go back to having no cover once one has been set. If you want a different image, upload it and it replaces the current one. If you want no cover at all, that state is only available before the first upload.
This is a separate issue from what happens the moment a replacement lands on a published journal, which is covered in The journal cover updates the live page immediately.