I want to edit a photo (photo name will be same and the image will change). But, my dev environment doesn't have Author. So, may I know how can I edit existing photo?
You can upload files via CRX Explorer on AEM Publish at /crx/explorer/index.jsp ..make sure you login as a user w/ permissions to create a node where you need it.
You could try /miscadmin and see if you can upload through that to /etc/designs - but that might not let you in AEM Publish (havent been there in years!)
you can login to the publisher with a local or admin account and make changes directly in the publisher using the UI.
How the dam content is pushed to your publish instances ? Did you check with your team ? Even though we can make changes via CRXDE ( given you should have permission to login ) I will say don't make any changes in the publish directly. That is not how AEM is designed to perform . If you think your AEM Dev has no Author ( which I am not sure why !?) please reach out to your team and understand from where the content is pushed to the publish. Go via the proper medium. Publish should be used only to check your final product whether image or page .