Example of the default bicubic scaling applied to images in Safari and Chrome on retina displays. Note the blurriness of the envelope and both the small alien head and the large olympic alien. Also because the default scaling uses antialiasing, images with tight croppings appear be cut off near the edges. For example the bottom edge of the "reddit" text in the main logo, or the ears on the small alien head.

Same view with nearest neighbor scaling applied. Assets remain crisp with no antialias bleed around the edges, at a normal viewing distance these images look no better or worse then a lower dpi screen.