The Apple computer company introduced a new version of its popular iPad Wednesday, with a sharper screen (featuring the "retina display"), an improved (5 MP) camera, and the ability to use Verizon's 4G LTE wireless service, a faster method to access the Internet over cellular networks. 

The iPad is a mobile computer and the new version has a nearly 25 centimeter screen.  Apple's iPad is the best-selling of the so-called "tablet" computers, and the improvements are apparently designed to help it keep its market share.

The Bloomberg financial news service says Apple will probably account for about two-thirds of the more than 100 million tablet computers that will be sold this year.

Apple also unveiled an upgraded version of its Apple TV box that allows users to take high quality video and audio programs from the Internet and elsewhere and play them wirelessly on high definition televisions and other devices.

The device is more powerful than the previous version and is about the size of a paperback book.