Originally Posted by Owen
Bluray video is encoded constant image width, its 1920 pixels wide for both scope and 16:9 while the number of active vertical pixels varies depending on aspect ratio. For constant image quality and maximum immersion the display should also be CIW and there is the added advantage of not needing to zoom or use an A-lens, just set and forget.
For most of us (and in what would amount to standard use) "image quality" is how the image looks, and not the number of pixels that happen to make up the image per se. You can have plenty of pixels and awful image quality and visa versa, and you can have constant number of pixels and varying image quality, which is in fact what we have on Blu-Ray or DVD. So given image quality actually varies in our source, pointing to a constant in the pixel count doesn't address the problem of picture quality. You don't get "constant image quality" by using the same amount of pixels or having a CIW system. Plenty of CinemaScope movie transfers can look even better at a CIH width (wider than 1:85:1) than some 1:85:1 AR movies shown at a narrower size. Depends on the transfer and movie, etc.
Further, if you see a Scope movie on a CIH system, and switch back and forth to that movie being much smaller w. black bars at a CIW size, there's no way you can say the CIW size produces "maximum immersion." The greater immersion for scope movies is one of the prime motivations for CIH.
Of course you could just make your 1:85:1 image much larger - as wide as you would have gone with your CIH system. But then in terms of image quality you compromise the image quality of some of your 1:85:1 images (the poorer sources) by making that large - the problem of the fact there is no "constant image quality" to begin with, whichever way you go. Further, due to the "contrast effect" size-wise, your scope image on your 1:85:1 screen will feel perceptually less immersive, given it's size will shrink relative to your 1:85:1 content.
Which is all to say: the issues in home theater, given the variables and varying goals, is far too complex to say one ought to go CIW for the reasons you had given.