Among this fall's numerous portable-device updates are two that feature greatly improved displays – Apple's iPod Touch and the latest generation of the Amazon Kindle.

The new iPod Touch incorporates Apple's "Retina Display," introduced last summer in the iPhone 4. The 3.5-in. 960 x 640 capacitive-touch display has a high-enough pixel density that, according to Apple's literature, "… your eye is unable to distinguish individual pixels." RGB pixels are arranged on a horizontal grid spacing of 78 μm, resulting in 326 pixels/in. The display uses LED backlighting and has an ambient-light sensor that automatically adjusts the luminance of the screen for optimal viewing and battery life. While at least two major display manufacturers have been cited by journalists as makers of the display, Apple did not respond to inquiries on this subject. The iPod Touch has two cameras, front and back, which enable the FaceTime calling feature that debuted with the iPhone 4. It also comes with HD 720p video recording and a faster processor, Apple's A4 chip.

Writing about the Retina Display as used in the iPhone 4, Charles Annis, Vice-President of Manufacturing Research for DisplaySearch, said that the new display is so compelling that it has upped the ante for many similar products. As he wrote in a recent article, "The release of the June 2010 iPhone 4 with its 327-ppi Retina IPS-LCD has sparked great interest in super-high-density displays for smartphones."

Less colorful but just as compelling is the display used in the latest Kindle from Amazon. Admittedly, the product's most arresting feature may be its $139 price tag, but the Kindle also features the stunning, latest-generation, super-high-contrast, electronic-ink technology from E Ink. The device is 21% smaller than its predecessor, but a thinner bezel allows the 6-in.-sized reading area to remain the same. The new 8.5-oz. Kindle is also 15% lighter, offers 20% faster page turns, and features built-in WiFi, as well as up to 1 month of battery life with the wireless off. The new Kindle has double the storage of the last version, to a total of 3500 books. Amazon is also offering the Kindle 3G, which adds free 3G wireless for $189.

– Jenny Donelan