07/09/2022

## How do you detect Canny edge?

Process

1. Apply Gaussian filter to smooth the image in order to remove the noise.
2. Find the intensity gradients of the image.
3. Apply gradient magnitude thresholding or lower bound cut-off suppression to get rid of spurious response to edge detection.
4. Apply double threshold to determine potential edges.

What are the 3 basic objective of canny edge detection?

Find the intensity gradients of the image. Apply non-maximum suppression to get rid of spurious response to edge detection. Apply double threshold to determine potential edges.

### Is Canny edge detector linear?

The Canny edge detector is a linear filter because it uses the Gaussian filter to blur the image and then uses the linear filter to compute the gradient.

Why is Canny edge better than Sobel?

The main advantages of the Sobel operator are that it is simple and more time-efficient. However, the edges are rough. On the other hand, the Canny technique produces smoother edges due to the implementation of Non-maxima suppression and thresholding.

#### What is aperture size in Canny edge detection?

apertureSize – aperture size for the Sobel() operator.It is the size of Sobel kernel used for find image gradients. By default it is 3.

What is double thresholding in Canny edge detection?

The Canny edge detection algorithm uses double thresholding. Edge pixels stronger than the high threshold are marked as strong; edge pixels weaker than the low threshold are suppressed and edge pixels between the two thresholds are marked as weak.

## Why does the Canny detector have two thresholds?

Now you can see what the double thresholds holds for: High threshold is used to identify the strong pixels (intensity higher than the high threshold) Low threshold is used to identify the non-relevant pixels (intensity lower than the low threshold)

What is threshold in Canny edge?

The ‘Canny’ method uses two thresholds. For example, if the threshold is [0.1 0.15] then the edge pixels above the upper limit(0.15) are considered and edge pixels below the threshold(0.1) are discarded. Now, you may have a question “what about the pixels in between upper and lower threshold”?

### What is CV Canny?

Advertisements. Canny Edge Detection is used to detect the edges in an image. It accepts a gray scale image as input and it uses a multistage algorithm. You can perform this operation on an image using the Canny() method of the imgproc class, following is the syntax of this method.

What is aperture size in Canny?

apertureSize – aperture size for the Sobel() operator.It is the size of Sobel kernel used for find image gradients. By default it is 3. L2gradient :L2gradient which specifies the equation for finding gradient magnitude.

#### What are two thresholds in Canny edge detection?

Canny does use two thresholds (upper and lower): If a pixel gradient is higher than the upper threshold, the pixel is accepted as an edge. If a pixel gradient value is below the lower threshold, then it is rejected.

What is aperture size in canny edge detection?

## How is hysteresis thresholding used in the Canny edge detector?

The thresholder used in the Canny operator uses a method called “hysteresis”. Most thresholders used a single threshold limit, which means if the edge values fluctuate above and below this value the line will appear broken (commonly referred to as “streaking”).