A UV image is an image taken with film or a sensor which is sensitive to light in the ultraviolet band of the electromagnetic spectrum. It is important to note that although the result of ultraviolet photography is a visible image, ultraviolet light is not visible to the human eye, and the visible image is actually created through the use of false color which assigns color values depending on the intensity of the exposure to ultraviolet light. UV images can be used in a wide range of settings, and are especially popular in scientific research.
Two techniques can be used to obtain a UV image: reflected ultraviolet photography and ultraviolet fluorescence photography. Both require equipment which is capable of handling light in the ultraviolet area of the spectrum. This includes specialized film for film cameras, and UV-sensitive sensors in digital cameras. It is also necessary to use filters with the camera lens, or to use a lens which has been specifically developed for use in UV photography.
To take a UV image, the photographer uses a filter or lens which blocks out visible light, allowing only UV light into the camera. When the picture is snapped, the film or sensor is exposed to the UV light, creating a UV image. Sometimes, a filter which allows blue and violet light into the camera is used, creating a rather eerie appearance in the finished image.
In the sciences, UV images are taken of space, planets, and other objects of interest in the universe to collect more information about them. These images are taken from space because the Earth's atmosphere interferes with ultraviolet light and can obscure our “view” in the ultraviolet spectrum. Patterns which previously could not be identified may become visible when people look only at the UV area of the spectrum, and this imaging technique can also be used to do things like discover new planets and stars. In this case, the image may be color processed before being released to the public, but people should be aware that the colors they are seeing are artificial.
Scientists can also use a UV image to identify special markings on plants and animals. Flowers in particular are known for having markings which are only visible to animals which can sense ultraviolet light. Bees, for example, see the world differently than humans do, and they can identify little landing strips and other markers on flowers which humans can't see. A UV image can be used to get an idea of how bees might see a particular flower, which can provide interesting information about bee life.