[JohnCrooks]

Originally Posted by Geoff D

Because it's a non-standard resolution compared to the 16:9 frame size that's the standard for home video. And if you put a 2048x858 (2.39) image into the 3840x2160 UHD frame it'd basically take up less than a quarter of the screen! If we take that up to 4K res, with a 4096x1716 image, then the horizontal resolution will not fit consumer UHD displays so it would need to be either bordered to fit (that's before you even get to to the 2.39 letterboxing), scaled to fit, or cropped to fit which chops off 256 pixels.

That is of course the reality that content providers face every day, that one does not fit into the other, and they have that exact same decision to make. Putting out 2048/4096 content isn't an option, so they scale or crop to 1920/3840 horizontal res. Scaling retains the proper dimensions and all of the available picture area, but (as Kirsty said) it's not a linear process and quality can sometimes be lost, resulting in stuff like aliasing. If they crop the image to fit you'd get the best quality every time, but not the full picture area.

Simply put, it's all a compromise in one way or another, and adding the "true size" of the image into the mix would cause too much consumer confusion, although I admit that it'd be nice to make that decision (scale or crop) for ourselves after seeing the piss poor job that some studios make of the scaling.

I do understand all of that. I suppose the answer to my question then is, because it would look small (relative to screen size), on an UHD display.