Japanese companies have developed a 12.1-inch ultra-high-definition display module designed for high-end notebook computers and tablets. Japan Display Inc, a consortium that includes Sony, Toshiba and Hitachi, developed the prototype, which was presented at the FPD International convention in Japan. So what does this mean for the resolution of handheld displays and what are the implications for Ultra-HD screens?

With a 365 pixels per inch, the 3840×2160 display measures 273mm x 164mm, or just over 12 inches or 300mm across the diagonal. It has four times the resolution of a high-definition television screen.

Japan Display Inc prototype of a 12.1 inch Ultra-HD screen

For comparison, the 7.9-inch iPad mini ‘Retina’ display has a pixel density of 326 pixels per inch and a resolution of 2048×1536 pixels. The iPad Air has the same resolution but with a 9.7-inch screen has a resolution of 264 pixels per inch.

As informitv has previously observed, the benefits of ultra-high-definition displays may be more apparent on smaller screens that are viewed at close range.

After all, 3840×2160 pixels is only just over 8 megapixels, while a full ‘high-definition’ television frame is only 2 megapixels. Most consumer still cameras record over 10 megapixels, while professional models shoot images of over 20 megapixels.

It is a common misconception that around 300 pixels per inch approaches the limits of human visual acuity. Photographic images are often originated at this resolution for printing. However, conventional printing typically involves much higher resolutions of 1200 pixels per inch. Text output at 300 pixels per inch appears grainy by comparison.

So there may well be benefits in ultra-high-definition displays for smaller screens, particularly for text, graphics and photographic images.

Japan Display has also announced mass production of 5-inch full-HD 1920×1080 pixel screens, using its WhiteMagic technology to combine red, green, blue and white subpixels to improve brightness for outdoor viewing while reducing power consumption.

Again, for comparison, an iPhone with a 4-inch ‘Retina’ display has a resolution of 1136×640 pixels, which is significantly less than even a 720p high-definition picture.

So it seems we can soon expect to see smartphones and tablets with screens capable of natively displaying at least full high-definition video images. That means high-definition video will become increasingly standard across all screens.

Viewing video on a tablet may not involve an inherent compromise, and may be a more personal, intimate and involving experience, like listening to music on headphones rather than what used to be called a “hi-fi” or “stereo” system.

This begs the question, if we want that sort of resolution on a smartphone or tablet, is high-definition really good enough for the living room display?

A 32-inch high-definition television has a display density of less than 70 pixels per inch, while on a 50-inch screen that falls to 44 pixels per inch.

Even without Ultra-HD programming, viewers will see the benefits of higher definition screens in higher quality graphics and vastly improved reproduction of digital photographs. Meanwhile, high-definition material can be scaled up to take advantage of the extra pixels.

No surprise then, that the latest speculation that Apple may come out with an Ultra-HD display. After all, it already sells screens 2560×1440 pixel 27-inch screens that considerably exceed the resolution of high-definition television.

In which case, informitv has long-expressed doubts that the illusive Apple TV screen will be a television. It would be more characteristic for Apple to reinvent television as a smart screen, without a tuner, that will create a new category of display and redefine our conception of television.