iOS Why do we need two images for retina?

[jPuzzle]

I'm still confused about the whole @2x system having to include two sets of images
Why can't you just include 1 hi res image won't that automatically get scaled down on a non retina device?

Thanks Chris

 

[nuckinfutz]

Because the quality of scaling would deliver compromised quality.

 

[cMacSW]

You don't need to do this, but you will get better results across ipod, iphones and ipads at the various resolutions.

 

[Scott90]

Because the quality of scaling would deliver compromised quality.

This, more than anything. Resizing iPad retina quality down to standard quality is definitely noticeable on the 3GS or other non-retina devices.

 

[ppilone]

Depending on the size of the images you may also see a memory/performance impact on older devices scaling down large images.

So your options are provide one hi-res image but sacrifice quality and performance on old devices or provide standard and hi-res versions of the image and not sacrifice anything on any devices.

 

[robvas]

Also, different re-sampling algorithms have different results. One might make photos look good, but wreak havoc on line art or text

http://en.wikipedia.org/wiki/Image_scaling