High Dynamic Range (HDR) photography is a system for recording more detail in shadows and highlights than standard 24-bit photography is designed to handle. The greater the range between the brightest and darkest points in a photo, the more it can benefit from HDR.
The 6G iPod touch is the first 64-bit iPod touch, following the iPhone 5S, 6, and 6 Plus in leaving behind 32-bit operation. It is also the first iPod touch with a 128 GB configuration, which is only available directly from Apple.
The 5G iPod touch uses the same 4″ widescreen display as the iPhone 5 and the same dual-core Apple A5 CPU as the iPhone 4S. It was also the first iPod touch available in colors other than black and white and the first to use the Lightning port.
The 4G iPod touch brought a Retina Display and Apple CPU to the iPod touch line, along with a front-facing FaceTime camera.
The 3G iPod touch is even more powerful than the 2G iPod touch, with a faster, more efficient processor, twice as much system memory, and improved graphics.
The 2G iPod touch is about 30% more powerful than the original iPod touch and was the first one with Bluetooth. It was also the first iPod touch with volume buttons and a built-in speaker.
As part of its huge September 2007 iPod event, Apple introduced the first iPod touch, essentially the original iPhone with its phone circuitry removed.