es volume into the sector represents at time of writing about 4% of the global market by volume but captures something of the order of 50% of the gross margin achieved across the sector. This means that component vendors are in turn under less price pressure. The iPhone has an effective realised price including subsidies and rebates that is higher than many lap tops and although the display is small relative to a lap top its added value is higher and its cost is lower. The display in an iPhone 4 for example is estimated to have a realised value about ten dollars, rather more than the RF components used in the phone. So while we are on the topic of imaging let's skip to another value domain - display-based interaction. 5.2.4 Display-Based Interaction - A Game Changer When Apple released its league table of the best-selling iPhone apps from its 'first 10 billion' downloads earlier this year, 8 out of 10 were games. Clearly games on mobile make money but the value realisable from games is at least partially dependent on the screen and screen input capabilities of the host device. The iPhone and the iPad both use capacitive touch screen displays with a flexible transparent surface and transparent conductive layer. An oleophobic coating is used to stop greasy fingers leaving marks on the screen. The capacitors are organised in a coordinate system. Changes in capacitance across the coordinate points are input into gesture interpretative software that is referenced against knowledge of the application that is running at the time. This makes possible all those thumb and finger pinch and spread features that people now take for granted. Simple really but no one had thought to do this prior to 2007 or rather no one had actually done it. Apple benefited substantially from having first-mover advantage. Table 5.2 shows some of the added feature sets across the first four generations of iPhone. The iPhone 4 has a 3.5-inch diagonal 24-bit colour display with 960 by 640 pixel resolution at 326 ppi, an 800 to 1 contrast ratio, 50