A CSS media query that captures almost all high DPI aware devices.

high-dpi-media.css

/* ---------------------------------------------------------- */
/*                                                            */
/* A media query that captures:                               */
/*                                                            */
/* - Retina iOS devices                                       */
/* - Retina Macs running Safari                               */
/* - High DPI Windows PCs running IE 8 and above              */
/* - Low DPI Windows PCs with IE zoomed in                    */
/* - Low DPI Windows PCs & Macs with Firefox zoomed in        */
/* - Android hdpi devices and above                           */
/* - Android tvdpi devices, including Google Nexus 7          */
/* - Chrome running on high DPI Macs and PCs                  */
/* - Opera running on high DPI Macs, PCs and mobile devices   */
/*                                                            */
/* Please note that that this code assumes you'll swap a      */
/* 2× version of your images. If you'd like to supply         */
/* finer increments, other thresholds might be appropriate.   */
/*                                                            */
/*                                  @marcedwards from @bjango */
/*                                                            */
/* ---------------------------------------------------------- */

@media	only screen and (-webkit-min-device-pixel-ratio: 1.2),
	only screen and (-o-min-device-pixel-ratio: 5/4),
	only screen and (min-resolution: 120dpi)
	{
		/* Your code to swap higher DPI images */
	}