eReaders, such as the Amazon Kindle, suffered a seasonal dip in the second quarter of 2011, down 9 percent sequentially to 5.4 million units, while year-over-year growth was 167 percent, according to the IDC Worldwide Quarterly Media Tablet and eReader Tracker.

Amazon led the market with a 51.7 percent share for its Kindle eReader, followed by Barnes & Noble with 21.2 percent for the Nook.

With product refreshes and following strong 2Q11 sales, IDC expects eReader shipments to grow significantly through the holiday season, reaching a total of 27 million units for the year, up from a previous projection of 16.2 million units.

"We expect major vendors to offer their current-generation black-and-white eReaders for less than $100 by the holidays," said Tom Mainelli, research director, Mobile Connected Devices.

"We're also expecting Amazon's much-rumoured, colour LCD-based tablet to ship later this year.

“Because we expect it to run a customized version of Android that ties its use to Amazon's content services, we expect the device to more closely resemble Barnes & Noble's Color Nook than Apple's iPad 2.

“As a result, our current plan is to count it as an eReader, and that will also help drive shipment numbers."

"eReaders are also gaining traction with a combination of increasing function and affordability, as well as greater device and content availability," added Jennifer Song, research analyst, Worldwide Trackers.

"The strong first half performance and an improved view of eReader positioning helped boost our outlook for shipment volume."