Constant Image Height home theater viewers take note: VUDU now offers (for free) the ‘Transformers: Dark of the Moon’ teaser trailer in high definition with 21:9 anamorphic enhancement. It’s not much, but it’s something.
I expect that the majority of people reading this blog post will probably have no idea what I’m babbling on about. First things first, let me direct you to my 2.35:1 Constant Image Height Tutorial. The CIH movement is admittedly a niche within the home theater community, but those of us who do it are passionate about it.
One limitation of 2.35:1 CIH projection is that “scope” movies available in high definition (including Blu-ray) are encoded in letterbox format with black bars eating up a chunk of the available resolution. Since a Blu-ray frame is 1920×1080 pixels, only approximately 1920×815 of those pixels are being used for the active picture content on a 2.35:1 movie. The rest are wasted on the black bars.
To project this onto a 2.35:1 screen, viewers have two options. With the Zoom Method, the letterbox bars are simply allowed to spill off the top and bottom of the screen while the active movie content is zoomed to fill the screen. Alternately (and more expensively), the anamorphic lens method requires that the picture be scaled to vertically stretch the image. This cuts off the letterbox bars, but leaves you with a geometrically distorted picture.
An anamorphic lens will then stretch the image horizontally to restore proper geometry.
The anamorphic lens method has the advantage of using the entire 1920×1080 resolution of the display. However, the extra pixels are interpolated, not real picture content. Unfortunately, the Blu-ray format was not designed with anamorphic enhancement in mind (as you’ll see on DVD with 16:9 enhancement). The creators of the Blu-ray format did not take the needs of Constant Image Height into consideration. Blu-ray pixels are square, and the letterbox bars are baked into the image.
Technically, there’s nothing to prevent a content owner from transferring a movie (or, in this case, a movie trailer) with a 21:9 stretch. When played back on a standard 16:9 HD screen, the image would appear distorted. But when played back with proper CIH gear, the proper picture geometry would be restored. The main reason this hasn’t been done is that Blu-ray players do not have the ability to downconvert a 21:9 anamorphic picture to standard 16:9 letterbox (like DVD players can downconvert anamorphic 16:9 DVDs for playback on older 4:3 TVs).
For whatever reason, a copy of the ‘Transformers: Dark of the Moon’ teaser trailer was transferred in 21:9 format, and can be viewed in the Trailers section of VUDU. There is no downconversion option. Either you can watch this on a 16:9 screen where it will look stretched, or you can watch it on a 2.35:1 screen with anamorphic lens, where it will look correct.
There’s not much to this. It’s just the movie’s two-minute teaser trailer, the one where the astronauts investigate the spaceship on the moon. Honestly, it’s not all that exciting. In fact, the trailer appears to be 720p resolution and has some severe color banding artifacts (and the audio is only Dolby Digital stereo). This isn’t going to be a flawless home theater demo. But it’s an interesting development all the same.