Threshold value (electronics)
As a threshold value (engl. Threshold ) is referred to in the signal and image processing a value which is used as a boundary for the processing of a signal:
- if the value falls below the threshold, the input value is mapped to an output value of zero;
- when the threshold value is exceeded, the input value is mapped to a constant output value (usually to 1).
This converts the signal into binary values ( binarization ), as is the case with analog-digital converters , for example . Corresponding circuits are called comparators .
The term is the same regardless of whether the signal is represented electronically in analog form or already as a digitally coded data signal (like the gray-scale coding of a digitally transmitted image that represents a range of values).
For example, an attempt can be made by means of a threshold operation to separate a dark line drawing from its light background in an image ; The brightness value of the individual pixels serves as the basis . With Morse code it is sufficient to check whether the sound exceeds a certain minimum volume.
Mathematically, the application of a threshold value can be defined as a Heaviside function from an input signal f to an output signal h with a threshold value θ .