Rice Exercise

Published: Friday, 27 December 2013


Sample of Rice Grains from a Harvest

Task: Calculate the proportion of the integer grains with respect to the broken ones. After the harvest, the quality of the rice is determined by the proportion of the healthy, fully grown rice seeds. The proportion of integer seeds is an important factor in the rice's quality, as first class rice seeds are those which are unbroken. Also from the agricultural point of view the fully grown rice seeds are important during the sowing, as the broken seeds will not germinate.

Approach: Threshold the image, and work on its binary version A. There are three categories: integer grains, broken grains and clusters of grains. The third one has to be reduced, but one cannot eliminate it completely. Moreover the connected components of A that hit the edges must be removed. For splitting the clusters, one observes that they are unions of overlapping convex sets. Compute the distance function of A and its watershed, and take the set difference between A and the divide lines. Then terminate with individual analysis of the connected components.

Keywords: convex shapes, clusters, watershed of a distance function, edge effects, individual analysis.

1. Thresholded Image   2. Distance Function of Thresholded Rice   3. Watershed of the distance function(using minima of the distance function as marker).   4. Thresholded image cut with the watershed to separate rice grains
5. Border Removed   6. Half Grains   7. Integer Grains   8. Other Grains

Comment: The procedure is governed by 3 assumption – First, the grains are convex, so that the distance function is a good way to separate overlapping grains. Second, When a grain is broken, the rupture occurs usually in the middle so that 3 size histograms of the broken, integer grains and clusters are separated. Third, We don’t need a complete segmentation for getting a significant result. “There remains a few clusters nevertheless”.

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