Variable Thresholding |
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For this extension, we explored variable thresholding of images. Instead of
choosing one threshold, we picked two; an upper and a lower. In an ideal world,
the upper threshold would indicate sky, and the lower threshold would indicate
tree trunks. Everything in between would indicate leaves. In reality, it does
not work so perfectly: to get an accurate picture, the thresholding would have
to be done at a much higher resolution. We did produce some code that
demonstrates the basic idea though. In the following image, the mask was
produced based on a high threshold for sky, a low threshold for tree trunks,
and a variable(percentage) threshold for the amount of light getting through
leaves. More correctly, the lower threshold cuts out trunks and dark leaves
which are not allowing light through; the light grey areas show leaves which
are allowing some light through. Variable Thresholding Example The percent sky for this image was found to be 22.23%, as compared to 18.37% for auto single region thresholding, 18.48% auto multiregion thresholding, and values of 11.42% and 19.65% respectively for manual thresholds of 155 and 125. The base image is the American Beech July image. |
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| Swarthmore College - E/CS 27 - Fall 2003 | ||
