The 'flagship' image should be the best representation of a particular set of functionality.
This image will be used on an important page in the doc space which describes that functionality. The image will also be used in other spaces, such as the ATLAS space. This is a way to ensure that the images displayed in other spaces are kept up to date. The assumption is that the flagship image will be updated whenever necessary, as part of the normal documentation updates at each software release. (That's why the image should be used in a prominent place.)

To use an image from this page:

!MYSPACE:_Flagship Image^ImageName.png!

For example:

!TEMPLATE:_Flagship Image^EclipseBuildLog.png|border=1,bordercolor=gray!

(info) You can remove the EclipseBuildLog.png image from your own space — it's just an example.