An explanation of single image sizes in the Google+ stream.
View the Google Plus Image Sizes presentation on Scribd.
Slide 1 – Image Container
The image container is 402px width x 301px height.
Slide 2 – Horizontal Images
Horizontal images display at 402px width, variable height and align top.
Slide 3 – Portrait Images
Portrait images display a variable width, 301px height and align left.
Slide 4 – Square Images
Square images display at 301px width x 301px height and align left.