If consumer-oriented and professional digital photography calculates with megapixels, high- resolution digital photography is already about gigapixels. This enormous image resolution is used in espionage technology, but is also used for satellite images for geological surveys, land surveying, online map services, geowebs and large-format panoramic images.
A gigapixel photo is a bitmap with 1 billion (`10^9`) pixels, about 40,000 x 30,000 pixels. This is equivalent to one hundred times the size of a 10-megapixel digital camera. Since digital cameras with a corresponding image resolution do not yet exist, the photos are assembled from many individual shots using special software, or a large-format negative with a high resolution is scanned. For example, the image of New York's Harlem neighborhood consists of 2,000 individual shots and has a file size of 13 gigapixels. Newer camera developments can scan the images directly.
In addition to the recording technology, the playback technology plays a decisive role because the familiar playback programs cannot be used for images of this size. Adobe and Microsoft have therefore developed special image viewers. With Adobe, the pixels are arranged pyramid-like in several layers with different resolutions. While the full image is still displayed with a low resolution, the images of the subsequent levels are each stored with four times the resolution. When you zoom in, the full image fades to the detailed images of the subsequent layers, which are stored at a higher resolution.