Logitech C-920 High def stills

Feb 14 at 7:55 PM
I am using the WPF Media Kit for a Photo Booth I am building.
I am capturing the video at 1920 X 1080 and displaying it in a preview window in my WPF app without issue.
I am also able to render the preview image and save it to a file.
If I set the desired pixel size to 1920 x 1080 the file created is at that resolution and looks pretty good, but if I set the desired resolution higher the image is created at that higher resolution but the quality is no better (or worse)
That camera supposedly will do up to 15 MP.
1920 x 1080 is 3 MP and apparently that is the highest supported resolution for video mode.
But the camera can create stills up to 15 MP.
But I don't know how to capture the HD stills using WPF media Kit or something else.
Please help.