This guide explains how to perform a correct intensity range setting and all the related adjustment operations needed to improve the image visualization.
Using intensity range and visualization settings
Basic concepts
Dynamic Range
The dynamic range of the image represents the number of discrete values (Gray Levels) that make up the numerical scale used for the conversion of the analog signal into its digital form. The gray scale has several predefined ranges (8bit-256 GL, 12bit- 4096 GL, 16bit-65356 GL). The range is also called Bit-depth.
The dynamic range of the image is determined by the physical features of the acquisition device used.
Grey Scale
Each numeric value (bin) on the gray scale represents an intensity level. The wider the numerical scale, the smaller the level described by each bin.
Intensity Range
The Intensity range of the image represents the real number of Grey Levels describing the source signal intensity.
The Intensity range always fits with the dynamic range. However, it could occupy only a small part of the whole dynamic range, typically the lower part. This happens especially when the Bit Depth is bigger than 8 bits.
Full Dynamic Range
By default, the full dynamic range is mapped on the monitor screen for visualization purpose (Display Range). This means that when the Intensity range is described by few grey levels, a dim or an almost black image is displayed. The intensity information is there but the observer cannot distinguish the image details.
Color settings
Basically, the Color Settings panel allows to modify the Dynamic Range mapping as already shown above, but with a different approach. The range limits can be adjusted by dragging the lines at the beginning and end of the graph.
The target channel must be selected before moving the graph limits.