Good day! OMV forumers. 1st off, I know there is already a guide on this topic here, but after I fiddle around with it today for hours, I found out how to properly change the wallpaper without any script.
I won't cover how to replace file within linux/debian environment as it is not my intention to do so here, but I believe there are plenty ways to do it and there are plenty guides in the internet for your to explore, be it using CLI or SSH like a pro or setup file browser and mount the root directory with root privilege or using SFTP software such as FileZilla using root account too are fine, just pick your poison...
To begin with this topic, I would like to thank npaezduin for the initial guide and info on the location of the wallpaper which is at /var/www/openmediavault/assets/images/, particularly we are looking for the 3 picture files which are login.jpg, standby.jpg and shutdown.jpg.
The difference between these 3 files are pretty much self explanatory by its name, login.jpg is the background picture used on your login page, standby is the background picture used when you issue command on OMV to standby using webgui as well as for shutdown.jpg correspond to shutdown command.
To replace the background picture you would only replace the corresponding picture file (login/standby/shutdown) with another picture file of your choice but the new picture must be in jpg format and keeping the same file name (login.jpg/standby.jpg/shutdown.jpg) with user:group is root:root and permission rw-r--r--. I had tested this quite some time, any picture in jpg format will work fine regardless of picture dimension or aspect ratio, for optimal please do keep the image ratio around 17~18:9 for optimum view with your browser maximized on your screen with 16:9 ratio. There is no harm if you use a 16:9 ratio wallpaper as browser will automatically crop out some region of the wallpaper.
FYI: renaming file extension of another format to jpg does not mean the picture is now converted to jpg format, don't be silly. The proper way of converting a picture of another format to jpg format is open the picture with your picture viewer/editor and perform save as into another file with jpg format, or use TRUSTED online free picture converter, some may have watermark in the converted picture though and beware some fishy website provide this service to embed malware into the converted picture to infect any PC opening the picture file, use them on your own risk.
Now, after replaced the picture file, as explained by forumer npaezduin, no matter how you refresh the browser or restart the NAS your login/standby/shutdown background will not change on your browser. Yes, I found this too abit weird, but not until I perform "Delete Browsing Data" and remove only the "cache images and files" as well as selecting the time range to "All Time", after done clearing cache image then refresh the login page again and voila~, it is done.
for Android phones (particularly google chrome apps), you need to close the app (swipe out from recent app too or just perform force stop in the app info if you will) and then clear cache in app info and reopen the OMV webgui again, the background should be refresh with the new background that you use.
*please do your own finding with other Android/iOS web browser how to clear app cache
hope the above guide would be of help and I wish you to have a nice day with your OMV login page with new background
