Apple Design: The twenty pixels that changed design forever

Source: Apple Design: The twenty pixels that changed design forever, Design Lovers, 8:24, uploaded 2025-05-19, playlist index 258.

In June 2013, at WWDC, Apple introduced iOS 7 with an animation of circles and lines assembling the new logo. The first visual detail already carried the argument for the new system. The icon corners looked as if they used a 12-pixel radius, although their curve did not behave like the rounded squares in earlier versions of iOS. The shape was a squircle, the equal-axis form of a superellipse.

Design Lovers follows that small change from nineteenth-century geometry through a Stockholm traffic plaza, iOS 6 and iOS 7, and the Nokia N9. Its question is simple: why does this particular transition from straight line to curve feel more settled than an ordinary rounded corner?

From Gabriel Lamé to Piet Hein

The history begins with the French mathematician Gabriel Lamé, who described a family of shapes with formulas. The video explains the superellipse through a movable control. An ordinary ellipse can become plumper until it reaches a circle. Pushed further, it approaches a rectangle with smoothly rounded corners. Turned in the other direction, it can resemble a rhombus. The shape changes whilst remaining part of the same mathematical family.

The Danish engineer and mathematician Piet Hein later used a superellipse for a large traffic plaza in Stockholm. The result gave cars a route that felt smooth whilst fitting a city built from straighter blocks. A circle would have needed more space, and a rectangle would have introduced sharper changes of direction. Hein’s plaza gave the shape a physical task before software gave it a visual one.

The video calls the equal-axis version a squircle. It treats the icon as a digital descendant of this geometry, with the same movement between a square and a circle.

The corner as a continuous turn

A standard rounded rectangle joins a straight edge to a circular corner. The eye can locate the join because the line changes direction at a clear point. The superellipse spreads that change over a longer curve. The edge starts to bend before it reaches the corner, so the transition feels continuous.

The video explains the difference through driving. A car moving around a rounded-square junction reaches a turn and then follows it. A car moving around the superellipse enters the turn gradually. The same relation appears in the icon. The geometry removes a small visual interruption that the eye can detect even when the difference is hard to name.

Design Lovers connects this continuity with a general preference for smooth forms. It says that the result feels more harmonious and gives the product a slightly higher sense of quality. The psychological claim remains attached to the video. The source offers the impression as an explanation for the shape’s appeal rather than as a measured result that the note can verify.

The pixel measure is a visual shorthand

The video returns to the number that gives the title its scale. iOS 6 used icons that appeared to have a 10-pixel corner radius. In iOS 7, the corners looked closer to 12 pixels. Adding two pixels to an old icon, however, produced the wrong result. The curve still lacked the continuous behaviour of the new shape.

That makes the pixel count a useful description of the visual effect rather than a complete design instruction. The important change sits in the curve’s progression, which a single radius cannot describe. The designers had to reproduce a relation between the edge and the corner instead of increasing one measurement.

Curvature as a system

The video credits Apple’s chief designer Jony Ive with the wider change. During the move to iOS 7’s flat design, Apple used the squircle as part of a larger effort to unify the experience. The icons carried the same softened logic into the objects around them.

An iPhone is not literally a superellipse, according to the video, although its edges follow a similar rule. Curvature continues beyond the point where an ordinary rounded corner would finish. The closer an object sits to the user’s eye and hand, the more of this softening Apple applies. The icon therefore echoes the physical product without copying its outline.

The video links this choice to a study it calls “Preference for Curvature”, published in Frontiers in Human Neuroscience and placed in 2016. It says the study found that smoother shapes produce a more positive emotional response. The speaker turns that finding into a small competitive advantage. If every product feels safe at roughly 96 percent, an extra half percent may help one product feel more comfortable. The number is presented as a joke with a business point behind it. The effort spent on a detail matters when a company applies the detail across every surface.

The result is a more complex construction that reads as a simpler system. Icons, phones, watches, and computers share a family resemblance because their curves follow related decisions. The video treats that consistency as part of Apple’s sense of order. The geometry remains difficult to see directly, yet it changes how the whole set of objects belongs together.

Apple as populariser

The video gives Apple credit for making continuous curvature familiar across consumer electronics and digital interfaces. Earlier mathematics and physical design had already supplied the idea. Apple put it in the hands of people who used phones, computers, watches, and app icons every day.

That distinction matters to the source’s history. The small corner becomes influential because Apple distributes it through a tightly controlled system. The geometry gains cultural force from repetition across products, even when most users never learn the name squircle or notice the underlying formula.

Nokia N9 and the timing of iOS 7

The final turn points to Nokia. Two years before iOS 7, the Nokia N9 shipped with MeeGo, flat software, and icons that already used squircle-like forms. The video places those icons beside the appearance of iOS 5, whose visual language still belonged to Apple’s earlier period.

Nokia was already declining in 2011, although it remained a major phone maker. Design Lovers calls it highly probable that MeeGo influenced the look of iOS 7, or at least influenced when Apple chose to bring this approach to its software. That is the video’s strongest historical inference. It does not show a documented exchange between Nokia and Apple, so the resemblance and the timing carry the claim.

The story therefore ends with a qualification to Apple’s authorship. Apple made the squircle widespread and built it into a coherent product system. The underlying geometry had a longer life, and another phone company had already put a similar idea on a flat mobile interface.

Limits

The video gives no bibliography for its history of Lamé, Piet Hein, Apple, Nokia, or MeeGo. It names “Preference for Curvature” without authors, a DOI, or a URL. The psychological effects, the 96.5 percent comparison, and the claim that MeeGo influenced iOS 7 remain claims made by the speaker here.

The title refers to twenty pixels whilst the narration repeatedly refers to 12 pixels. The video does not explain the difference. Its later chronology also needs care: the opening places iOS 7 at WWDC in 2013, whilst the curvature study is described as appearing in 2016. The note follows the argument without treating either the pixel count or the study as a settled design or research record.

Further reading / references

• The video refers to a study titled “Preference for Curvature” in Frontiers in Human Neuroscience. It supplies no authors, full title, DOI, or URL, so the reference remains unidentified here.