Adjust transparency of pictures on slides

The Make Transparent turns the selected image or shape slightly transparent. This can be used to fade an image for use in the background of a slide, as shown above.
To apply the feature, select the image and click  Make Transparent from the Effects Lab dropdown.

 This feature can be useful in 'toning down' any picture so that it does not attract unnecessary attention, for example, making a logo less conspicuous:

The 'Make transparent' feature comes with the free PowerPointLabs add-in and works for both PowerPoint 2010 and 2013 on Windows.