More precise estimates for the Jensen operator inequality obtained via the Lah-Ribarič inequality

In this article we establish several converses of the Jensen operator inequality. The obtained inequalities are related with the usual convexity instead of operator convexity, and are derived by virtue of the improved version of the Lah-Ribarič inequality. First we give our general results, some of which improve some recent results known from the literature. The general results are then applied to quasi-arithmetic and power operator means.