iPhone 4 review

The iPhone 4 is developed by Apple. It is the fourth generation of iPhone, and successor to the iPhone 3GS. It is particularly marketed for video calling, consumption of media such as books and periodicals, movies, music, and games, and for general web and e-mail access. It was announced on June 7, 2010, at the WWDC 2010 held at the Moscone Center, San Francisco, and was released on June 24, 2010 in the United States, the United Kingdom, France, Germany and Japan.

The iPhone 4 runs Apple's iOS operating system, the same operating system as used on previous iPhones, the iPad, and the iPod Touch. It is primarily controlled by a user's fingertips on the multi-touch display, which is sensitive to fingertip contact.

The most noticeable difference between the iPhone 4 and its predecessors is the new design, which incorporates an uninsulated stainless steel frame that acts as the device's antenna. The internal components of the device are situated between two panels of chemically strengthened aluminosilicate glass. It has an Apple A4 processor and 512 MB of eDRAM, twice that of its predecessor and four times that of the original iPhone. Its 3.5-inch (89 mm) LED backlit liquid crystal display with a 960×640 pixel resolution is marketed as the "Retina Display".

Display

The display of the iPhone 4 is designed by Apple and is manufactured by LG. It features an LED backlit TFT LCD capacitive touchscreen with a pixel density of 326 pixels per inch (ppi) on a 3.5 in (8.9 cm) (diagonally measured), 960×640 display. Each pixel is 78 micrometres in width. The display has a contrast ratio of 800:1. The screen is marketed by Apple as the "Retina Display", based on the assertion that a display of approximately 300 ppi at a distance of 12 inches (305 mm) from one's eye is the maximum amount of detail that the human retina can process. With the iPhone expected to be used at a distance of about 12 inches from the eyes, a higher resolution would allegedly have no effect on the image's apparent quality as the maximum potential of the human eye has already been met.

This claim has been disputed. Raymond Soneira, president of DisplayMate Technologies, said in an interview with Wired Magazine, that the claims by Jobs are something of an exaggeration: "It is reasonably close to being a perfect display, but Steve pushed it a little too far." Soneira stated that the resolution of the human retina is higher than claimed by Apple, working out to 477 ppi at 12 inches (305 mm) from the eyes.

Camera

The iPhone 4 features an additional front-facing VGA camera, and an improved (backslide-illuminated, big physical pixel size) 5 megapixel rear-facing camera integrated with an LED flash. The rear-facing camera is capable of recording HD video in 720p at 30 frames per second. Both cameras make use of the tap to focus feature, part of iOS 4, for photo and video recording. The rear-facing camera has a 5× digital zoom




.Gyroscope and accelerometer

The iPhone 4 introduces a gyroscopic sensor that detects 3-axis angular acceleration around the X, Y and Z axes, enabling precise calculation of yaw, pitch, and roll. The gyroscope complements the accelerometer, a sensor that has been present since the original iPhone, which detects the device's acceleration, shake, vibration shock, or fall by detecting linear acceleration along one of three axes (X, Y and Z). The combined data from the accelerometer and the gyroscope provides detailed and precise information about the device's 6-axis movement in space. The 3 axes of the gyroscope combined with the 3 axes of the accelerometer enable the device to recognize approximately how far, fast, and in which direction it has moved in space.

Processor and memory

The iPhone 4 is powered by the Apple A4 chip, which was designed by Intrinsity and, like all previous iPhone models, manufactured by Samsung. This system-on-a-chip is composed of a Cortex-A8 CPU integrated with a PowerVR SGX 535 GPU. The Apple A4 is also used in the iPad where it is clocked at its rated speed of 1 GHz. The clock speed in the iPhone 4 has not been disclosed . All previous models of the iPhone have underclocked the CPU, which typically extends battery life and lowers heat dissipation.

The iPhone 4 has 512 MB of eDRAM. The additional eDRAM supports increased performance and multi-tasking.

Storage and Micro-SIM

The iPhone 4 uses a Micro-SIM card on iPhone 4 devices running on a GSM network, which is positioned in an ejectable tray, located on the right side of the device. On a CDMA network, however, the phone connects to the network using an ESN. All previous models have used regular Mini-SIM cards. Depending on the operator, Micro-SIM cards may not be available for all networks globally. As a technical workaround it is possible to trim a Mini-SIM card with a knife or scissors so that it fits into the Micro-SIM tray.

As on previous models, all data is stored in flash memory, 16GB or 32GB, and not on the SIM. Unlike previous generations, the storage capacity is not printed on the back of the unit.

FaceTime

The iPhone 4 supports FaceTime, an embedded video calling application that is able to use either the front or back camera over a Wi-Fi connection to communicate with another iPhone 4, the fourth-generation iPod Touch, or any Mac computer running Mac OS X 10.6 Snow Leopard.