32×32 is slowly becoming the new 16×16.

16×16 was born

First of all, let’s go down the memory lane.

“Icons” were one of the most important part of GUIs (Graphical User Interface), and surely one that sets it apart from CLI (Command Line Interface). In the very beginning, there was only 32×32. The earliest graphical operating systems, e.g. Mac System 1.0, spotted only 32×32 icons.

Why 32×32, not 30×30, or even better, 1cm by 1cm? The size of the icon, using my educated guess, is due to the need to pack the files tightly inside a cluster in the file system. The first icons are monochrome, which consist of just 0s or 1s. 32×32 would mean 1024 bits = 128 bytes, which can be packed snuggly into clusters. The size was the compromise between system limitations and ergonomics. 32×32 would be about 24mm by 24mm in a normal 13” monitor back then.

While icons smaller than 32×32 were sometimes used in toolbars or file managers, it did not come to the front stage until Mac System 4, where smaller 16×16 icons are used in its Application Menu. Windows 95 later took this step forward to create a complete and colored Start Menu.

During the 1990s, we slowly transcended from 72dpi CRTs to the first 96dpi LCDs. By the first years of 2000s, we all had around 96dpi for our monitors. At this point, a 16×16 icon measures about 5mm x 5mm. (Try that on your monitor.)

16×16 is odd

We had the leisure of translating our system icons from jagged 2D to fully anti-aliased 3D, as system capabilities advanced.

However, it is not easy for the human eye to recognize a 3D icon clearly when the icon is so small. All the perspective illusion begins to fail, the pixels are squished together to become one blurry image, due to the limit of these 256 pixels, and that our eyes just cannot see that well (would be nice if someone can give me more citation on that).

As icons are pictograms of the software they are representing, they are pragmatic by nature. While aesthetics is helpful for daily usage, a strong correlation between the graphic and its text is more important.

To rectify the problem, 16×16 usually gets a special treatment: They are drawn in flat 2D as if they were graphical symbols to keep them easily recognizable with a good level of detail, for example:

32×32 joins the family

In the latest build 7048 of Windows 7, we see a new shift: The team drew some new 32×32 icons, in 2D.

As people have higher and higher pixel density for their monitors, it will be appropriate to have the 32×32 to be included as part of the ‘mini’ mode. In a couple years, 144dpi monitors will become the norm (e.g. your iPhone or G1 are already 144dpi). By then, a 32×32 icon will measure only a measly 5.5mm x 5.5mm – right back where 16×16 used to be.