In a direct challenge to Apple Inc.’sdominance of the tablet computer market, the online retailer Amazon.com Inc. unveiled more powerful versions of its Kindle Fire tablet Thursday, including one nearly as large as the iPad but priced hundreds of dollars less and a version of of its e-reader that feature a next-generation screen from E Ink Corp. of Cambridge.
“I think it’s very smart,” said Sarah Rotman Epps, a senior analyst at Forrester Research in Cambridge. “It’s a compelling lineup of devices that will be very competitive with the iPad.”
The new Kindle Fire HD will be available with either a 7-inch screen for $199 or an 8.9-inch screen, at prices ranging from $299 to $599. By contrast, Apple’s iPad has a 9.7-inch screen and is priced from $499 to $829.
Amazon also appeared to address widespread criticism of the screen quality on the original 7-inch Kindle Fire, saying both sizes of the Fire HD will include higher-resolution screens. The new tablets will also have at least twice as much memory, front-facing cameras for videoconferencing, and stereo speakers with audio-processing software developed by Dolby Labs.
Top-of-the-line units will include the ability to access 4G LTE wireless Internet services at $49 a year; previous versions were offered with Wi-Fi and 3G cellular connectivity.
Amazon is taking orders for the new tablets immediately. The 7-inch version will begin to ship on Sept. 14, and the 8.9-inch Fire will be available Nov. 20.
Amazon will also offer an improved version of the original Kindle Fire at $159, but with a larger battery, more memory, and a faster processor than in the previous edition.
Amazon also unveiled a new Kindle e-book reader that features an illuminated screen developed by E Ink for reading in darkened rooms.
“The higher resolution makes the images a lot nicer,” said E Ink’s chief marketing officer, Sri Peruvemba, who said his company modified the layers of material in the screens to make images appear more paper-like.
The Kindle Paperwhite’s screen will have 62 percent more pixels than the black-and-white screen of the current Kindle, so text will be appear clearer and easier to read.
“Paperwhite is the Kindle we’ve always wanted to build,” s Amazon’s chief executive, Jeff Bezos, said in a press release. “The technology didn’t exist to build a display with this level of contrast, resolution, brightness and battery life, so our engineers invented it.”
The Kindle Paperwhite will sell for $119 for a basic version that connects to Wi-Fi wireless Internet services, or $179 for a version that can download electronic books over 3G cellphone networks. Amazon is taking orders for the device and will begin shipping it on Oct. 1.
Amazon will also offer a non-illuminated basic version of the Kindle for $69.
No company has managed to effectively compete against Apple in full-size tablets; only smaller devices like the Kindle Fire and Google Inc.’s Nexus 7 have done well. One reason is that all other full-size tablets have cost as much as or more than the iPad.
Roger Kay, president of Endpoint Technologies Associates Inc., a Wayland research firm, said Amazon can put such a low price on the Fire HD because buyers will probably increase their purchases of other Amazon products.
Kay also said the new Fire tablets and the Kindle Paperwhite mean big trouble for bookseller Barnes & Noble Inc., which has had some success with its Nook line of e-books and tablets.
“There’s not much room in the market for also-ran competitors,” Kay said. Between the iPad and the Kindle, he predicted that Barnes & Noble will fall far behind its two giant rivals.
Apple did not respond to a request for comment. Barnes & Noble declined to comment.
“I feel like the Nook is collateral damage with this,” Kay said. “Amazon has its eye on Apple and doesn’t care so much what Barnes & Noble does.”