Change login screen in Sierra

so how did you finally change the login wallpaper?

When I go to /Library/CoreData I have nothing in it but an ExternalRecords folder.

Also in my /Library folder I have no DesktopPictures folder.

I can find the alias in /System/Library/CoreServices/DefaultDesktop.jpg but it is just an alias as you said.

any other ideas?

For Sierra:

The alias points to /Library/Desktop Pictures/Sierra.jpg. Overwriting that file will change your login screen to a blurred version of the image you put there. Higher the res the better as it will use the version best for the screen.

If you rename that file to a backup or something like that (sierra.jpg), the alias will follow that file. Overwriting is key.

For El Capitan:

The com.apple.desktop.admin.png under /Library/Caches/ works for El Capitan and if you replace that file, the picture will be un-blurred.

***Have not tested making the change in El Capitan and then upgrading to Sierra to see if the Login Image is still the same***

PS - its /Library on the root of the drive, not /Library under the Users folder

Yep Works perfectly. Fixed all issues stated above .. I just wish it was Blurry. Any Input to achieve Blurry will be appreciated.

THANKS!!!!!! I was wondering why it stopped working. I did my edits In Photoshop and resaved as a PNG and It worked. I need to add that you will need to make sure not to compress the Image on the 2nd window when saving it as a PNG file.

Found the DesktopDefault.jpg in system>library>CoreServices but what are the steps to overwrite it?

My hope is to replace the blurred image of the orange mountains at login with a clear counterpart (Sierra.jpg)

The original file, Sierra.jpg that the DesktopDefault (alias file) points to is the clear version of the mountains image and the one I want to display under the login. But it seems like there is some script involved that blurs the image underneath at login/screenlock as to not compete with the login window? Because when cached, the orig sierra.jpg converts to the blurred png.

How does one fix this?

Apologies -- want to clarify previous post above; my question is in reference to how to replace the blurry Sierra mountain scene after awakening from 'sleep mode'. When you awaken the computer and it asks you for login password. The question was not in reference to the regular background desktop picture after you login or the image that comes up after a computer boot or restart. Many thanks for anyone that can help.

I have to hold the SHIFT (LH or RH, doesn't matter) key to view "Library" in the menu.

If I click the OPTION key, the ⌥ symbol appears beside the "Enclosing Folder" keyboard shortcut.

Sierra v. 10.12.2

I dont understand how your image is not blurred. I have been able to change the background image but I cant seem to take away the blur.

Sierra.jpg worked for me. 9,2 with 10.12.3.