Gigapixel images are extremely large digital photos. One pixel is one individual picture point in a digital picture. The prefix giga means "billion". Thus, a gigapixel image is composed of at least 1 billion picture points. A 20 gigapixel image shows approximately 100 times more details than one single picture taken with a high-quality digital camera. Gigapixel photos are taken with conventional digital cameras, usually equipped with powerful telephoto lenses.
Numerous small, slightly overlapping sections of a motif are photographed one after the next. These individual images are then calculated using a high-performance computer programme and stitched into one overall picture. Usual large-scale posters dimensions are 3.5 m x 2.5 m, printed with a resolution of 150 dpi. If you printed a 20 gigapixel photo, it would be 64 times as large as such large-scale posters.
In order to be able to contemplate it in all its clarity, it can be divided again into individual images. By using a special viewing software, these are then combined into sections to be selected interactively by the user. The user can work with the mouse in order to view the reduced overall picture or zoom into the picture until each and every pixel of the original image is displayed on the screen.