RE: EME impact on accessibility

I’m not responding to EME concerns, but perhaps providing a low vision AT fact or two for the day… Enjoy.

I knew that ZoomText allowed for user-specified color palettes in the browser, and so I again went to Netflix, launched a video, and then "applied" a customized color palette via ZoomText. Sure enough, it "worked" (were worked = the visual interface was modified by the software to provide the 'required' or specified color modifications). These changes were applied to both the "chrome" (user controls) as well as the content rendered in the view-port of the video player - even when I went "full screen". (I am unsure of *how* ZoomText achieves this, but it appeared that an overlay filter of sorts was invoked, as when I attempted to do a screen capture, the capture "lost" the colorization - I had to take a photo of the screen with the colorization
as "proof")
[Steve] ZoomText and other similar software achieve this using a mirror driver<https://en.wikipedia.org/wiki/Mirror_driver> – a kind of virtual filter on the actual hardware display adapter.  The upside to this is that the effects are applied no matter what content or software you are using, including virtual machine displays, multimedia, etc.  An upside to the screen capture effect would be that when I am presenting via WebEx, there is no interference with the display rendered to the participants since WebEx takes the unfiltered version.  The biggest downside to the mirror driver approach in my experience has been compatibility issues with graphics cards, drivers, and a few other very low level things.