Research group IDC estimates that Samsung sold 16.6 million tablets in 2012, lagging far behind Apple Inc. which sold 65.7 million iPads. But Samsung is on the rise, capturing 20 percent market share in the July-September quarterwhile Apple, which led the commercialization of tablet computing, fell to 30 percent. Apple previously had more than half of the global tablet market but its dominance has eroded as Samsung boosted sales with cheaper Galaxy Tab computers that offer many different screen sizes.