Getting the bigger picture

Several cameras now let you capture images that are larger than the pixel dimensions of their sensor. Angela Nicholson explains how

The primary purpose of an in-body image stabilisation (IBIS) system is to compensate for the accidental movements that occur when photographers are handholding a camera and therefore enable sharp images to be captured when using slower shutter speeds than normal. It works by detecting the camera-shake and shifting the sensor by tiny amounts to correct for it so that the image isn’t blurred.

The fact that the sensor can be moved very precisely enables another feature, usually called something like Pixel Shift Multi Shot mode or High Res Shot mode, that is now found in some cameras from Fujifilm, Olympus / OM System, Panasonic, Pentax and Sony. When the mode is activated, the camera takes a series of images, shifting the sensor by a tiny amount, sometimes half the width of a pixel, between each one. These images can then be combined into one image to either create a larger image with more detail, or in the early incarnations in Sony and Pentax cameras, images that have the same pixel count as normal but have slightly better detail, colour and tonal gradations.

In some cases, the images are combined using software running on a computer, but Olympus / OM System, Panasonic and Pentax cameras can composite the images in-camera when their High Res Shot mode or High Resolution modes are used. The most recent Olympus and OM System cameras, including the OM-D E-M1X, OM-1 and the OM-5 feature two modes: one that is suitable for use when the camera is mounted on a tripod and the subject is motionless; and the other which can cope with a little subject movement and when the camera is handheld. In tripod mode, the cameras produce 80MP images; while in handheld mode they produce 50MP images.

Using software