BOBCAT Hardware User’s Manual
Imperx, Inc.
Rev. 1.0
6421 Congress Ave.
5/4/2010
Boca Raton, FL 33487
+1 (561) 989-0006
109 of 212
3.2.1.2 Dual Threshold Binary
If the image has a low contrast and does not have well defined dark and
bright regions, the simple threshold operation does not yield good results.
In such cases a dual (known also as interval or window) thresholding
technique has to be implemented – Formula 3.2. The binary image output
is converted to “white” for all gray level values between the selected
threshold interval X1 and X2, and to “black” for all gray levels outside
(X1, X2) interval. The user can set the optimum X1 (Low) and X2 (High)
threshold values, please note that X2 > X1. Figure 3.2 shows the original a
processed image after a dual threshold operation.
Output signal =>
“BLACK” if (input signal
≤
X1)
“WHITE” if (X1 < input signal < X2)
“BLACK” if (input signal
≥
X2)
(3.2)
Figure 3.1 – Original and processed image with single threshold.
Figure 3.2 – Original and processed image with double threshold.
