McIDAS User's Guide
Version 2018.1
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Black and white contrast stretching.
The input brightness values correspond to the brightness values on the image frame. Input brightness values below inlo and above inhi are not changed. Inlo is output at value outlo and inhi at value outhi. Brightness values between inlo and inhi are output at values determined by linear interpolation from outlo and outhi.
When using the mouse-controlled version, moving the cursor to the right along the x-axis decreases the upper brightness bound (from level 255) to be enhanced as white (255). Moving the cursor upward along the y-axis increases the lower brightness bound (from level 0) to be enhanced as black (0).
Occasionally, a brightness range will contain a value that will not need to change as the new values are assigned by EB. In the example below, the data's brightness value of 104 happens to match the value assigned during the EB stretch. Since value 104 did not need to change, it becomes a breakpoint in the EU TABLE listing and is not shown on the output below. Command EB 62 164 2 250 produces output from EU TABLE like this:
Brightness Blue Green Red min max min max min max min max --- --- --- --- --- --- --- --- 62 103 2 102 2 102 2 102 105 164 107 250 107 250 107 250 |
Command EU SAVE will save the current enhancement. Command EU MAKE will apply color enhancements to any frame.
EB
This entry invokes interactive mouse-controlled contrast stretching. Press the right mouse button to end the process, leaving the current enhancement.
EB 50 150 0 255
This entry rescales input brightness level 50 as 0 (black) and input brightness level 150 as 255 (white). The 101 counts from 50 to 150 are linearly stretched along the 256 counts from 0 to 255.
EB 30 255 50 200
This entry rescales input brightness level 30 as 50, and input brightness level 255 as 200. The 226 counts from 30 to 255 are linearly stretched along the 151 counts from 50 to 200.
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