False color

In a false-color image colors are specifically used that differ from the natural color impression. Hence the term false color.

Scientists will use this to make fine nuances of a color or a shade of gray clearly distinguishable in an image. In the false-color image in a literal sense, the color channels of the original image, other colors are assigned - for example, red to blue and blue to green. In the color coding individual levels of brightness of a hue are assigned different color values.

Perception

Humans can perceive natural color stimuli as color stimulus. This transformation of the physical signal in a psychological perception takes place in the natural ( innate ) and " Experience has shown that influenced " LMS color space. Thus, a color stimulus specific spectral composition of all normal-sighted people from different cultures is "seen" almost the same. Usually, the goal is a pictorial representation, the natural color perception according to function properly, the transformation is done by the sense of sight requirements.

Painter with the oldest " imaging method" have used their artistic freedom. The painter succeeds willfully represent the perceived color stimulus to the model by selecting the color palette as other means of its individual color stimulus on the screen. As examples can be mentioned Blue Horse I, The Yellow Cow by Franz Marc Blue Horse on red grass of Mikhail Filippowitsch Shatrov and easily find other paintings.

Brain imaging methods, it is possible to convert the spectral composition of the picture elements on the " input side " in a different color space and so spend as false color. Unintentionally it happens in case of failure of the automatic white balance as a color cast. The intended applications slight differences in the color tone can be translated into more visible.

The false-color image based on the principle that the color perception of the human eye, although limited to a few hundred levels of brightness of a hue, but can differ about a million shades of color. Instead of a gray scale ranging from white to black, a color scale is used, which can range from yellow to red to blue. This produces images that reveal the details much clearer.

Applications

False color representation

Aerial photographs and satellite images are typical applications of the false color display. In these images is often not worked with color films, which are optimized for a natural color reproduction to the human eye, but it will be possible to image individual spectral ranges with color filters on black and white film or color- insensitive electronic sensors. Also invisible radiation such as ultraviolet or infrared light can be added. Such multispectral images are, for example, to easily distinguish vegetation areas of uncultivated land or built-up areas, even if they have a similar color to the human eye. In a false-color representation of the vegetation, for example, a shade of red will be assigned and the wasteland a shade of blue.

Color coding

Many imaging methods used in medicine, such as magnetic resonance imaging, ultrasound or X-ray tomography, or physics, such as thermography, produce images that do not contain color information. For such images are obtained a color-coded representation by the individual gray levels are represented by different colors in order to detect small nuances in the picture clearly. Images to display temperature differences are called heat map.

For example, different tissue types can be shown in different colors in the X-ray tomography. This is based on a high color resolution of the scanner used.