• Review of Region Filling and extractable features for recognition:
  • Area: sum all of the pixels belonging to a region
  • Centroid: sum all pixel locations in x and y then divide by area
  • Symmetry; check for equal pixel locations on each side of the centroid
  • Euler Number: number of "holes" in the object
• Convolution:
  • A mask is an arrangement of numbers which is used to filter an image
  • To apply a mask to an image, it is convolved with the image by multiplying the mask pixelwise with the image, summing the products, and placing this result as a pixel in a new image.
  • Into which pixel the result is placed needs to be determined and kept consistent.
  • You may need to pad the image at the edges in order to finish the convolution. This can be acheived by padding with zeros or with the edge pixel value.
  • In digital signal processing, the mask is actually flipped around when applying convolution. In the world of robotic vision, it is generally accepted that the mask is applied as is.
• Introduction to the Handy Board: (.ppt)

Convolution examples
24-354 General Robotics
Fall-02. Prof. Howie Choset