Retina sprite generation using sass

mixins.sass

@mixin sprite-background($name)
	background-repeat: no-repeat
	background-image: $standardImg
	background-position: sprite-position($sprites, $name)
	height: image-height(sprite-file($sprites, $name))
	width: image-width(sprite-file($sprites, $name))
	@media (-webkit-min-device-pixel-ratio: 1.5), (-o-min-device-pixel-ratio: 3/2), (min-device-pixel-ratio: 1.5)
		background-image: $retinaImg
		background-position: 0 round(nth(sprite-position($sprites2x, $name), 2) / 2)
		height: round(image-height(sprite-file($sprites2x, $name)) / 2)
		width: round(image-width(sprite-file($sprites2x, $name)) /2 )
		/** width of largest image in non retina folder **/
		+background-size(290px auto)

style.sass

/** image directory **/
$imgdir : "/static/1/images"

/** wildcarded import function for retina and non retina **/
@import "non_retina/*.png"
@import "retina/*.png"

/** create sprite in sass memmory **/
$sprites: sprite-map("non_retina/*.png")
$sprites2x: sprite-map("retina/*.png")

/** url of generated sprites **/
$standardImg: url(#{$imgdir}/non_retina-sfe26373e53.png)
$retinaImg: url(#{$imgdir}/retina-s9b09948543.png)

/** compass sheets required **/
@import compass/utilities

@import mixins

.img
    +sprite-background(image_name_without_extension)