min-device-pixel-ratio

Devices with -webkit-min-device-pixel-ratio: 2.0

All Macs with Retina displays
Apple iPhone 4
Apple iPhone 4S
Apple iPhone 5
Apple iPhone 5c
Apple iPhone 5s
Apple iPhone 6
Apple iPad (3rd generation)
Apple iPad 4
Apple iPad Air
Apple iPad mini (2rd generation)
HTC One X
Google Galaxy Nexus
Google Nexus 4
Google Nexus 7 (2013 model)
Google Nexus 10
Motorola Moto X
Samsung Galaxy S III
Samsung Galaxy Note II
Sony Xperia S
Sony Xperia T

Devices with -webkit-min-device-pixel-ratio: 2.6

Nokia Lumia 930

Devices with -webkit-min-device-pixel-ratio: 3.0

HTC One (M7)
HTC Butterfly
Huawei Honor 6
Apple iPhone 6 Plus
LG G2
Nexus 5
OnePlus One
Oppo Find 7 (X9076)
Samsung Galaxy S4
Samsung Galaxy Note 3
Samsung Galaxy Note 4
Sony Xperia Z
Xiaomi Mi 3

@media only screen and (-webkit-min-device-pixel-ratio:2) {
img{ background-image: url(images/@2.png);}
}

@media only screen and (-webkit-min-device-pixel-ratio:3) {
img{ background-image: url(images/@3.png);}
}

这些是针对图片做处理！