How to update your Google+ cover photo
The width of the image needs to be 2120 pixels. If you go any higher, the upload just sits there. I watched it for twenty minutes. If you go lower, the image will be fuzzy and pixelated.
Another consideration is that when it displays, it will remove the top 1/3 of the image. Yes, even if you have cropped it exactly the way you want it. No, I don't know why they do these things. The solution is to find an image with a BIG sky where the cropping won't matter. Not very scientific, I know, but it works.
Also, there will be text reversed out along the bottom of the image. That is, the lettering will be white. Google+ adds some hazy darkness down towards the bottom, but if you don't like that, just choose an image that is naturally dark along the bottom. I found a photo I took of a sunrise with LOTs of sky and a very dark bottom part.
In addition, your face now displays in a circle. Of course, it still displays in a square for the posts, so you have to make sure that it works in both formats. Chances are good that if your face looks good in a square, it will look good in a circle, but it's good to check.
Also note that where you work, where you went to school, and the city where you live are prominently displayed. I like that, but if you don't, go edit your profile and change it, or delete it.
Again, I don't know why they do this stuff, I'm sure they mean well!
Posted by Brad Hall