Chromecast Backdrop

Spent some time yesterday trying to find out why Backdrop photos were so dark on my TV. Was it the HDMI position, my photos, but no, others photos were dull too.

At least I discovered that my photos were perfectly bright when Cast directly, as were others photos. This could be seen when in the Chromecast app on the Backdrop page where one can follow the slideshow, and View Photo whenever you want to do a compare.

So I wrote a brief query on the Chromecast Community and so far received a couple of ansers that were no help. The first guy claimed his were OK, though I still wonder.

Could Backdrop be using a different path to the Chromecast device vs Casting from a device, i.e. is the latter more direct and/or of higher resolution?

Will see if this receives more answers anon.