Hysteresis thresholding in image processing

1. What is hysteresis thresholding?
2. How is hysteresis thresholding used in the Canny edge detector?
3. What is the purpose of thresholding in image processing?
4. How many thresholds are employed in hysteresis thresholding?

What is hysteresis thresholding?

Hysteresis is the lagging of an effect—a kind of inertia. In the context of thresholding, it means that areas above some low threshold are considered to be above the threshold if they are also connected to areas above a higher, more stringent, threshold.

How is hysteresis thresholding used in the Canny edge detector?

Hysteresis counters streaking by setting an upper and lower edge value limit. Considering a line segment, if a value lies above the upper threshold limit it is immediately accepted. If the value lies below the low threshold it is immediately rejected.

What is the purpose of thresholding in image processing?

Thresholding is a type of image segmentation, where we change the pixels of an image to make the image easier to analyze. In thresholding, we convert an image from colour or grayscale into a binary image, i.e., one that is simply black and white.

How many thresholds are employed in hysteresis thresholding?

Two types of thresholding are shown here. The standard mode just uses the lower threshold value to perform the threshold, whilst hysteresis uses both threshold values.