The iPhone 4S has a 1080p resolution, which means that it has 1,080 lines of horizontal resolution and 1,920 lines of vertical resolution (also called 1920 x 1080). This resolution is a significant improvement over that of the iPhone 4, which offers only 720p (called 1280 x 720), and an immense improvement over the iPhone 3, which has standard-resolution video (640 x 480), as shown in Figures 3 and 4. More lines of resolution mean more pixels (picture data), allowing richer, more detailed images.
Figure 3 This image was shot on an iPhone 3s, using the video camera with 640 x 480 resolutionor about 307,200 pixels.
Figure 4 With over 2 million pixels, this image was shot on an iPhone 4S, showcasing the richer 1920 x 1080 resolution.