© 2013 Thorlabs GmbH40
DCx Cameras
Image with linear characteristic
Image with gamma characteristic
Logarithmic characteristic
The effect of the logarithmic characteristic is even stronger. Here, the characteristic follows the function
The following diagram illustrates how very large jumps in brightness in light areas of a scene only cause small
changes in image brightness. This explains why image sensors with a logarithmic characteristic, in particular, are
ideal for imaging scenes with very high dynamic range.
Imaging with logarithmic characteristic
Lookup table (LUT)
With a lookup table (LUT) it is easy to apply characteristic curves to digital images. A LUT is a table which assigns
an output value to every possible input value. The figure below shows a LUT which would binarize an image: For an
8 bit image, for example, this LUT would replace all pixels with gray values 0...127 with value 0 and all pixels with
gray values 128...255 with value 255.
Using LUTs has the advantage that calculations can be done very fast. Typical applications of LUTs are enhancing
image contrast, or gamma characteristics.
LUT characteristic for binarizing an image
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