This procedure finds the image region that contains the vehicle license plate.
The gray-scale image of the vehicle is read. As we intend to use a MaxTree, the image is inverted so that the characters of the plate become image intensity peaks.
Here we build a MaxTree from the input image and apply a sequence of connected filters known as attribute openings. Each filter is implemented as a prunning of the tree and returns a new MaxTree. The filters are as follows.
wmax x hmax. This is like a sieve with a mesh of the specified size. Top hat means that we keep the components that passed the sieve.
wminare pruned out.
hminare pruned out.
mt1 = mmmaxtree(a);
mt2 = mmmaxaopenthmt(mt1, 'bbox', wmax, hmax);
mt3 = mmmaxaopenmt(mt2, 'bbox', wmin, 1000);
mt4 = mmmaxaopenmt(mt3, 'bbox', 1000, hmin);
mt5 = mmmaxaopenmt(mt4, 'volume', 500);
|Copyright (c) 1998-2008 by SDC Information Systems|