Is it possible to include a scale function to resize the captured images when they are very large.
Don't be alarmed, the Greenshot ticket system moved: http://getgreenshot.org/2014/06/22/greenshot-switches-to-jira-for-bug-reports-and-feature-requests/
With Greenshot 1.2 we have added scaling to the editor, we didn't release it yet but if you want to have a look at it you can download "unstable" builds here:
http://sourceforge.net/projects/greenshot/files/Greenshot/Greenshot%201.2/
We will look at other scaling options, e.g. when saving without editor, for Greenshot 2.x