Beginning App Asset Design - Part 11: Raster Basics | Ray Wenderlich

We'll answer questions like: What's a "raster"? What's the difference between points and pixels? What is resolution and how much do I need?

This is a companion discussion topic for the original entry at

Hi Catie,

how do you design an icon for e.g. a iPhone retina display? There are three sizes (pic.png, pic@2x.png, pic@3x.png).
Let’s say the ‘pic@3x.png’ has a size of 180px. Do you start with this size and then you go down to 120px for secont picture ‘pic@2x.png’ and then to the ‘pic.png’ with a size of 60px?

What I want to say is do you go from top to down (size) or do you prefer another technique to design the ‘right’ size?


@catie Can you please help with this when you get a chance? Thank you - much appreciated! :]