About those vector icons

This is an area Apple is perfectly, ideally positioned to execute and lead on.

EDIT: I wonder if one could implement vector icons as fonts in order to properly hint them.

That's exactly what is happening these days with custom font embedding having become practical (in web pages): http://somerandomdude.com/2010/05/04/font-embedding-icons/ (that was in 2010, but this thing is really gaining traction these days following the release of "Font Awesome" for Twitter's Bootstrap[0])

In desktop OS, that is in fact a very old technique, that's why the Marlett font exists in Windows [1].

It does have a significant inconvenient though: the icon can only have one color for the glyph and one for the background. This provides a crisp look but lowers the expressivity of the icons. On the other hand, if the color scheme changes for some reason (or can vary from one page to an other), it is very easy to match the icons's color scheme to that of the application.

[0] http://fortawesome.github.com/Font-Awesome/

[1] http://blogs.msdn.com/b/oldnewthing/archive/2012/01/16/10256...

Scaling artifacts occur because at smaller sizes the quantitization of the unit pixel overwhelms the details of the image. When I was a system programmer at the Image Processing Institute at USC (you know the source of that Lena picture :-) this was characterized as the frequency response of the display. So if you were to take a horizontal line across the pixels, and then plot their intensity vertically along a line (so x becomes the position in the line, and y is the intensity of the pixel at position x) then you can then do an FFT across those pixels and see the distortion in the visual signal from the source material to the displayed material.

Now the part that gets confounded in articles like this one is that the UX designer doesn't really want a 16 pixel icon, what they want is an icon that has a certain size with respect to the whole screen. Working backwards, lets say the icon ended up being 16 x 16 on a 1024 x 600 screen which had 72 pixels per inch. The icon is about 1/4" on a side (.22" but you get the picture). Now on a screen that that has 240 pixels per inch, that icon at 16 x 16 pixels is only .06" or nearly impossible to see, but if you keep it at 1/4" you get 60 x 60 pixels to work with.

So lets bring two things together, you do 'hinting' because the artifacts that are created by the quantitizing effect of pixelation cause you to lose information. As screen resolutions get denser the information lost goes down (less quantization, or more signal bandwidth is available) so once your signal loss from a straight mathematical shrink is acceptable in all required sizes your done.

Bottom line is that this won't be an issue when the minimum icon size is being rendered into a field of 128 x 128 pixels or more. Might take one more generation of screens.

The second thing is that while a designer can poke pixels to get an icon that looks good, so can the computer. One of the things you can do is compute the frequency 'footprint' of the image, then change the render until the render foot print is as close as you can get to the original. HP did this for their ink jet printer half-toning algorithm. In a 16 x 16 pixel space you could almost exaustively search it on a modern machine.

The article makes the bulk of the case for pixel optimization while discussing very small icons, and that's true, but it's a red herring. Interfaces should never rely on users being able to identify or interact with icons that are 16x16 pixels. At 64px, all of the icons seen in the article can be auto scaled successfully (in gimp, cubic transform): http://imgur.com/a/DOAyW

What we really need is to stop building hardware that demands 16x16 pixel elements, and to stop building interfaces that provide them. With high dpi screens, even character hinting becomes silly (or even without high dpi, I disable hinting on my 22" 1920x1080 screen because I like consistent letter spacing).

Pixel optimization experts may still have a place in the future, but it's likely in the same boat as audiophiles and $1000 HDMI cables.

Cool! Do you have a link/paper/book?