Which Kernel Does the IMAQ Edge Tool 3 Use?

Updated Jun 26, 2019

Reported In

Software

  • Vision Development Module
  • LabVIEW

Driver

  • Vision Acquisition Software

Issue Details

I'm using the IMAQ Edge Tool 3 VI to detect edges but cannot find out which kernel is used.
  • Which method is used to detect edges?
  • Which Kernel is used in this function?

Solution

The IMAQ Edge Tool 3 VI is using the Advanced Edge Detection method :
"The kernel operator is a local approximation of a Fourier transform of the first derivative. The kernel is applied to each point in the search region where edges are to be located. For example, for a kernel size of 5, the operator is a ramp function that has 5 entries in the kernel. The entries are {–2, –1, 0, 1, 2}."
Please follow the link to the NI Vision Concepts page, to find out more about the kernel.

The Advanced Edge Detection method is using the following steps to detect edges:
  1. 2D region extraction
  2. Rotation and interpolation of the 2D region (Zero Order, Bilinear or Biliear Fixed)
  3. Reduction of data to an 1D array (averaging or median)
  4. Kernel Application
  5. Parabolic fit for subpixel accuracy

Settings for this process:
  • Kernel Size - number of entries in the kernel or lengths of extracted 2D region
  • Width - width of extracted 2D region
  • Interpolation Type - type of interpolation used for 2D region rotation and interpolation
  • Data Processing Method - method used after the 2D region extraction to create a 1D array for the edge detection

Additional Information