In previous versions of Inventor the Alpah Channel is available for image exportation through Inventor Studio. The following blog post showcases the need and the process of creating this option...
http://blogs.rand.com/manufacturing/2010/01/inventomizations-image-export-options.html
Essentially the Alpha channel allows the abilty to remove the background from an Inventor image export so that it can be better utilized in PowerPoint and other print media without the extra processing being performed in a seperte editing software that a lot of designers are not familar with.
In Inventor 2016 the only way to get Alpha Channel is now through the Render Image dialog box if you choose the save image option before rendering even begins. If you render first and then save the image the Alpha Channel option goes away. This is a regression in technology from 2015.
As an enhancement to the software the ability to choose a Visual Style like Technical Illustration or Visible Edges only with a white background has been a go to for a lot of users to create compelling quick imagery. If the Alpha Channel could be added to the standard Image Export options in Inventor that would solve a lot of these issues, but currently that option does not exist.
