Notification Center is one of the highlights in Mountain Lion, and it is a direct adaptation of the same feature from iOS. The execution is spot on, but you will see a rather familiar background in Notification Center; the very same grey linen background that was previously used in Dashboard, and is still used in iOS. Not many users felt enthusiastic about the said background in Dashboard, which could easily be changed with tweaking tools or from within the system files. It might not have mattered much though since the Dashboard can be disabled and few people use it; however, the Notification Center is an entirely different story. It can’t be disabled, and it’s also incredibly useful, which means you will be using it even if bleeding kittens are in the background. This post describes how you can change the Notification Center background easily for one that appeals to you.
While the process is simple in itself, what’s slightly more complicated is getting the image right. We’ll go into that once we’ve discussed how you can change the background. Ideal dimension for an image are 256 x 256 and, for retina display, 512 x 512.
Go to your Mac HD and open Systems/Library/CoreServices. You will find an app called Notification Center here. Right click it and select Show Package Contents. A new folder called Contents should open, dig deeper into this folder and open the Resources one. This folder contains the background image and is named linen.tiff. Save this image to another location (in case you want to restore it), select a background image (it must be in TIFF format) and name it linen. Save it to this folder, authenticate it when asked and enter your password. Go to the Activity Monitor (Applications>Utilities) and quit the Notification Center app. When you open the panel now, your new background will appear.
Picking out the image is slightly tricky, and it is best to go with a pattern if you don’t have the patience to find the perfect image. The image should definitely be dark, since the text is white and will not be readable on a light background. The complexity of the pattern will also impact readability. For a more interesting background that makes use of the length of the notification panel, experiment with large images. Crop their width to 300 or 400 pixels and leave the length untouched. We used a 450 x 2160 sized image and were able to showcase the entire background effectively. It won’t work on all types of backgrounds where an object is too large to fit the 300 or 400 size so you will still need to pick carefully.
For users looking to change the Notification Center background in iOS, or make the Notification Center background transparent, visit the linked articles for the how-to.