Originally Posted by Vitus4K
I have follow-up questions, of course...
Why does not the JVC zoom the picture all the way out to 4096, filling the width as per the description found in the manual?
Page 26 (Zoom)
By following your calculations, it only seems to zoom the very same 6,66% as from 3840 to 4096.
I was hoping to achieve a horizontal stretch, but I guess that's impossible.
Maybe Oppo CIH 1/2x zoom and Auto from JVC?
That should horizontally stretch a 16:9 title, if I read the description correctly.
It's because the Oppo still outputs a 3840x2160 image, the 2880x1620 16:9 downscaled content is centered within that larger image and letterboxed and pillarboxed. From the projectors perspective it is receiving a 3840x2160 image which it then upscales to 4096x2160 (cropping off a bit of the letterbox bars on the top and bottom). When this is done on a 2.35:1 screen the resulting 16:9 image will be the correct height to fit the screen vertically and have black bars (pillarboxed) on the left and right.
Again, normal 16:9 content coming out of the Oppo is 3840x2160. This will use 93.8% of the projectors available pixels (assuming a 4096x2160 panel). However if the projector is zoomed to the width of a 2.35:1 screen the top and bottom of this image will fall off the edges.
Normal letterboxed 2.35:1 content is still 3840x2160 but the actual image area is 3840x1634 = 70.9% (or 3840x1620 for a 2.37:1 aspect ratio, 70.3% of the projector) of available pixels on the projector. The projector can then upscale this image to 4096x2160 (again cropping the top and bottom), the resulting image area is then 4096x1734, or 80.7% of available pixels. This is the best use of pixels when projecting 2.35:1 content onto a 2.35:1 screen with a projector that has a 4096x2160 panel.
When the Oppo is zoomed to 16:9 and the display is 21:9 Cropped it will downscale the original content by 0.75 (resulting in a 2880x1620 image) then center that image in a 3840x2160 output. When the projector receives this image it is receiving a 3840x2160 signal which it then upscales to 4096x2160. This results in the original image that was downscaled by the Oppo to become 3072x1728, or 60% of the available pixels on the projectors panel. When the projector being used doesn't have lens memory to quickly zoom between 16:9 and 21:9 this is a reasonable alternative that sacrifices resolution for convenience.