Block Category: Detection
Input Image Requirements: None
Description: The Canny’s Edge block finds the edges of objects using Canny Edge detection. Canny’s Edge uses thresholds to determine if pixels are part of an edge.
•Edges with an intensity gradient greater than the specified upper threshold are edges.
•Edges with an intensity gradient lower than the lower threshold are non-edges and are discarded.
•Edges with an intensity gradient between the two thresholds are classified as edges based on their connectivity. That is, if they are connected to “sure-edge” pixels, they are classified as part of edges. Otherwise, they are discarded.
Because edge detection can be affected by noise, you may want to apply a Gaussian blur (or filter) to the image before it is read into the Canny’s Edge block.
Lower Threshold: Specifies the lower threshold. Edges with an intensity gradient lower than the Lower Threshold are discarded.
Use input connector values to specify the threshold limits: Adds two input connectors to the block to dynamically change the minimum and maximum threshold values.
Upper Threshold: Specifies the upper threshold. Edges with an intensity gradient greater than the Upper Threshold are retained.
In this example, the Canny’s Edge for the lower display detects fewer edges because the values for the upper and lower thresholds have been increased (600) and decreased (10), respectively.
