I know that the adaptive thresholding function and its parameters are given below:
cv2.adaptiveThreshold(src, maxValue, adaptiveMethod, thresholdType, blockSize, C)
And I understand in the documentation it says:
C – Constant subtracted from the mean or weighted mean (see the details below).
Normally, it is positive but may be zero or negative as well.
I vaguely get the idea that this C is to determine where to set the threshold relative to the neighbourhood mean. My question is: Why not use the mean value directly? Why subtract a constant? What does this subtraction operation stand for mathematically? Could anyone please briefly explain it or guide me where can I find related materials to dive deeper? Thanks!