The enhancement file, enh.tab

The basic enhancement table

When you want to color enhance gray-scale images, you need to define a text file named "enh.tab" which contains your color tables and breakpoint information.

This described the format of this file.

Each line of the file is either a

• Comment Line (with # in the first column, or a blank line)
• Color Table Name (with * in the first column)
• Color Definitions in the form:
  In-low In-high Red-low Red-high Green-low Green-high Blue-low Blue-high

The In-low and In-high give the source (gray scale image) values (range of 0 to 255). The rest of the line, gives the Red, Green and Blue output scaling (also within the range of 0:255). For example, if one had:

50 100 80 100 0 50 40 200

this would mean that for the gray-scale range of 50 to 100 in the original image, the pixels would be colored by scaling the values for Red between 80 and 100, for green between 0 and 50, and for blue between 40 and 200.

Values that are not covered by one of the input ranges are left with their original gray-scale intensity. For non-gray scale values, the results are tenuous.

Each Color Table must have at least one Color Definition, but may have as many as are needed. Values may be separated by one or more spaces (NO tabs!).

Adding advanced parameters

In-low In-high Red-low Red-high Green-low Green-high Blue-low Blue-high Alpha-low Alpha-high

Where alpha values of 0 (zero) mean completely transparent; values of 255 are opaque.

In addition when you use the "probe" control, you should also supply the values for the probe readout. This is done by appending a values = list to the end of each line. For example:

50 100 80 100 0 50 40 200 values = -13.4, 22.9, 1

Where the value -13.4 applies to the gray value of 50, and the values of 22.9 applies to the gray value of 100. Linear interpolation will be used in between. The 3rd parameter, a "1" indicates that one decimal place should be shown in the readout.

Finally, you may also supply labeling information about units and an optional prefix to be shown. For example:

50 100 80 100 0 50 40 200 values = -13.4, 22.9, 1, K, Temp=

Would result in a probe readout in the form: " Temp = -13.4 K"

You do not have to supply the values for the number of decimal places, units, or prefix on each line if they are identical to the previously specified values. See the second example, below.

Simple form example

Complex form example

Now for a more complex example, used with the "probe" control and to colorize overlays automaticallys (see the "overlay_enhance_table" parameter). Note that in each table, the lower range of gray values is used for one parameter, while the upper range is used for a different one....