Image Thresholding

In order to create a binary image we use the Threshold module and set the threshold to a point at 190. Note that as the setting is manual your lighting for your parts should remain somewhat constant. Large changes in lighting will cause this segmentation to fail and parts of the background may be mistaken for foreground objects.

This is just one way of segmenting objects from the background. There are others such as the Automatic Threshold module or the Flood Fill module. These modules allow for the overall lighting to change in the image while still creating a reasonable thresholded image.

Before we add the Shape Matching module we need to create a database of files that contain the shapes we want to match. This is done by taking the above image and cutting the image using your favorite paint program and saving the individual shapes into each of their own files (.gif, png, ppm, etc.) within a single folder. This folder then contains 8 images one for each part. Below are the individual images used for training.

Note that the actual image sizes can be different and that only one object is shown in each image. Be sure to name the files with meaningful names as that will be the label used to identify the part.

Now onto shape matching ...