Can't Remove Blur from Pre-Login Wallpaper

[#1]

Hi,

I'm using a script that creates the pre-login wallpaper and saves it as com.apple.desktop.admin.png in /Library/Caches

The script:
1. Takes a source image (installed to each Mac via PKG)
2. Grabs the Mac Screen resolution via the system_profiler command
3. Using sips, resizes the image and saves this into /Library/Caches with the appropriate name
4. Resets ownership and permissions on the file

(Full script is available if necessary, or if you'd like to use it for your own purposes)

This process works, however at the login screen the wallpaper is shown as blurry. I've discovered that if I open this generated image using 'preview' and then just click save the blur is removed when I next log in.

Does anyone have any ideas what I might be missing with sips that mustn't be generating the image in a format macOS expects. The base template image was created in Photoshop and saved as a png.

Thanks
Ryan

[__Uss · Accepted solution]

you have done everything correctly, however, the image needs to be saved as a Transparent PNG. It can be done via photoshop or preview on the mac.

[#3]

Thanks @__Uss , I'll give that a try and let you know how it goes.

[#4]

Hi @__Uss

Your suggestion has resolved my issue.

Thanks for your help!

[sdmike]

Hi @rypowell88 ...

Would you mind posting the script?

[#6]

Hi @sdmike

I have a Github where I save copies of my scripts. The wallpaper one is here: https://github.com/rypowell1988/mac-management/blob/master/SetDefaultWallpaper.sh

Thanks
Ryan