Brain Imaging & Analysis Center

Displayed image intensity values can be clipped based on threshold settings. Thresholding can be controlled interactively using the Threshold ('K') command. The Taskbar “Thresh” icons provide a graphical interface for the 'K' command options. Preset threshold values can also be stored as parameters in XML image header files if desired. The <F7> keyboard key also provides a convenient way to set standard t-test threshold levels (Flag 4: +4.0 & -4.0).

Overview
For each image window there are 4 parameter values that control intensity thresholding:

• Mode - controls whether intensity thresholding is active
• Flag - controls how the Low and High threshold values are used
• Low threshold - low intensity value (floating point number)
• High threshold - high intensity value (floating point)

Mode options:

• 0 - thresholding is off; all intensity values are displayed
• 1 - thresholding is on; only display intensity values meeting the threshold condition

Flag options (threshold conditions):

• 1 - show values >= low threshold
• 2 - show values ⇐ high threshold
• 3 - show values >= low threshold AND ⇐ high threshold (low<high)
• 4 - show values >= low threshold OR ⇐ high threshold (low>high)
• 8 - only show boundaries of thresholded regions
• 16 - high threshold is a range; show values >= low AND ⇐ low+high

See Also:
Threshold ('K')

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