Hi sureshy2015
One of the approach could be, creating of costume component for assets uploading/Downloading.
// Pre-requisite
Create a Data Structure listing all the custom permission for all users.
eg. User ID Mod_Edit
aaaa 1
bbbb 0
This component will check if user has particular permission or not, and behave accordingly.
Reference Link:- https://helpx.adobe.com/experience-manager/using/developing-aem-osgi-bundles-jackrabbit.html (User Manager API)
Reference Link:- https://helpx.adobe.com/experience-manager/using/uploading-files-aem1.html (Custom Component for uploading of images, you need to create a logic according to your needs).
This way of doing the work will not allow user to edit the assets using this components, but they may edit it using other components (So create a templates having this component only).
I hope this will help you. I hope i am not missing on something.
Thanks and Regards
Kautuk Sahni