Auto Aspect Ratio for Anamorphic Widescreen

Tech Tip – Auto Aspect Ratio for Anamorphic Widescreen

Introduction to the Radiance Pro

The following tech tip refers to the potential for Lumagen’s new video processor family Radiance Pro™ to support auto aspect ratio for anamorphic viewing. Anamorphic format such as those used for IMAX has an aspect ratio of 2.39:1, meaning the (projected) picture’s width is 2.39 times its height, (this is sometimes approximated to 2.4:1). This is in contrast to the current most commonly used aspect ratio of 16:9.

Tech tip for anamorphic widescreen

“There are some machinations on the forums about changing aspect ratios during the movie for “iMAX” cuts on an anamorphic screen. This shows a lack of understanding by the posters.

For the past 20 years our motto at Lumagen has been “See what the director intended.™”

For whatever reason there are now “iMAX” versions for a few movies that are intended to be watched on a 16:9 iMAX screen. These movies have anamorphic portions and 16:9 portions. The 16:9 portions are typically shot on higher quality film than the anamorphic portions. So, the 16:9 portion is a much larger image and is a higher quality image in an iMAX theatre. I personally hate these aspect ratio transitions within a movie since they pull me right out of the movie. However, for an iMAX theater I yield to the director’s intent.

For anamorphic-screen based commercial theaters, and anamorphic-screen based home cinemas, the landscape (no pun intended) changes. We considered having a fast mode to change aspects immediately when the content changed aspect in a movie. We very quickly concluded that it would be dumb to do so, and would show a complete lack of understanding of the director’s intent.

If you have 16:9 TV then the iMAX version works like they would in an iMAX theater, except the 16:9 portion does not have better image quality. However, for an anamorphic screen, we need to follow the director’s intent to have the best viewing experience. If you went to a anamorphic-screen commercial theater and watched Interstellar, you saw the entire movie in anamorphic mode. Had the director wanted to show the 16:9 portion as smaller 16:9 images on the anamorphic screen, that is what would have been shown in the theater. It was not, and this is a clear indication of the director’s intent.

Changing aspect ratios mid-movie

iMAX movies that change aspect ratio have two “director’s intent” cases:

– iMAX on a 16:9 screen, with aspect changes from anamorphic it 16:9. The 16:9 portions are intended to be larger than the anamorphic portions, and they are. No auto-aspect change is needed for this case. You may want to disable auto-aspect, especially if you have masking. In other words, if you want to see the iMAX cut you should watch on a fixed 16:9 screen.

– For commercial, and home, cinemas with an anamorphic screen, the entire movie is intended to be viewed in anamorphic mode. The iMAX 16:9 portions are shot “protected for anamorphic viewing” and shown as anamorphic as intended. If you went to a normal commercial theater with an anamorphic screen and saw Interstellar, all content was shown as a single anamorphic aspect ratio. So, for the case of an anamorphic screen no auto-aspect is needed, and you should disable auto-aspect at the beginning of the movie (enable “sticky override” in the Auto Aspect menu).

There is a video recently posted that completely misrepresents the Radiance Pro, and ignores that Lumagen’s recommended practice is to disable auto aspect for these iMAX movies. Further, the video ignores the director’s intent. If the video had shown the Radiance Pro with auto-aspect disabled as instructed by Lumagen, the Radiance Pro version would certainly have been the preferred version. This is because it would not have any of the jarring aspect ratio changes and would be shown as an anamorphic movie as the director intended for an anamorphic screen.

What adds insult to injury is the video’s producer suggests Non-Linear-Stretch (NLS) can then be used on the 16:9 portions to fill an anamorphic screen. If there is something that would likely be considered sacrilege by movie directors, it would be using NLS on their 16:9 movie content to stretch it to 2.35 or 2.40. I personally do not like NLS in any case, but even those who do should refrain from using it to view 16:9 movie content on a 2.40 screen, saving it for TV shows and news programs. Leaving the entire movie as anamorphic for an anamorphic screen is the rational decision.

One final note:

We do have looking at changing aspects faster for auto-aspect on our list (again the start and end of the movie, the only places it should happen). The Radiance Pro intentionally adds a “hysteresis” delay to insure against false aspect change detections. It is certainly possible for us to have a variable to allow the viewer to change this time delay. We have been considering this for a future release since auto-aspect was introduced. It is just that it has not been a priority. After the pipeline enhancements are complete, if enough people want us to speed up the auto-aspect for the beginning and end of content, we might raise it higher on the priority list.”

Tip from Jim Peterson, President of Lumagen, Inc.