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DCx Cameras
Image capture and histogram with minimal contrast (le.) and with optimum contrast after a contrast
adjustment (ri.)
For improved display on the screen or when printed, the histogram can be spread to optimally utilize the possible
brightness levels. For this purpose, the dark parts of the image are further darkened via an LUT characteristic and
the light parts of the image are brightened. Thus the human eye can better differentiate between the different
brightness levels; the image has more contrast.
It must be noted, however, that subsequent processing with a computer will not yield more data. Therefore,
subsequent contrast adjustment via software is not necessary for use in image processing. The computer can
differentiate between the differences in brightness without contrast adjustment.
Advantage of greater bit depth with contrast adjustment
The bit depth in the output image is crucial for contrast adjustment. The following figures illustrate this. In the first
example the 8 bit output image contains fewer than 100 brightness levels, as there are no dark or very bright parts.
The image is low-contrast.
With a contrast adjustment, the values of the histogram are spread in such a way as to create a contrast-rich
image. The fewer than 100 brightness values are now distributed across levels 0 to 255; gaps arise in the
histogram and are visible as jumps in brightness in the resulting image.
Contrast adjustment with 8 bit output data
The second example shows the same output image with a 10 bit bit depth right at the time of capture. This image
also has low contrast, as it features only average brightness values. The greater bit depth allows the brightness
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