Movies on the new iPad - why 1080p isn't the full picture

Last week's announcement of the new iPad, complete with a so-called Retina Display, generated quite a buzz amongst movie fans. The revamped tablet boasts 1080p video support for the first time, stealing the lead from forthcoming Tegra 3-based Android tablets as well as leaving current 720p models in the dust.

"Over one million pixels more than a Full HD television", they declared. However, digging past the sensationalist headlines reveals a slightly different reality.

Despite the monster 2,048 x 1,536 pixel resolution, the fact that the 9.7-inch iPad retains the 4:3 aspect ratio means that widescreen video will be displayed in letterbox format. Full HD 1080p video (1,920 x 1080 pixels) will render those extra million pixels pitch black, adding nothing to the movie-watching experience.

In response to customers wanting a full-screen experience, Apple introduced a double-tap "zoom to full screen" feature with the iPad 2, but crunching the numbers, this risks delivering a substantially worse result.

The video is upscaled 42 per cent to 1,536 lines from the 1,080 lines of the source file, which risks introducing softness to the image. Of much greater concern is the fact that the video is now 25 per cent wider than the screen, resulting in almost 700 horizontal pixels thrown away. In extreme cases, entire characters are cropped out of the frame entirely.

The impact can be limited using a technique known as Pan & Scan, where the viewable area moves around to keep the subjects in frame; even introducing artificial cuts between close-ups if necessary. This is time consuming work and requires a re-edit of the film. A simple centre-weighted digital zoom is ignorant of a scene's make-up and results in the undesirable cropping.

Unfortunately, there isn't much that can be done given Apple's choice of 4:3 aspect ratio from the onset; the iPhone's 3:2 aspect suffers far less with widescreen video. The majority of Android tablets are widescreen, with several 2012 models with Ice Cream Sandwich announced with Full HD displays

There is no doubt that the high pixel density of the new iPad is a boon for web browsing and other text-based work like eBooks, producing pin-sharp fonts. Gaming will also look very sharp indeed. But for movie lovers, the jury is definitely out.