Image Processing Reference
In-Depth Information
(a) Line
(b) Wrench
(c) Wrench with noise
(d) Accumulator for (a)
(e) Accumulator for (b)
(f) Accumulator for (c)
(g) Line from (d)
(h) Lines from (e)
(i) Lines from (f)
Figure 5.7
Applying the Hough transform for lines
We can see that the HT delivers a correct response, correct estimates of the parameters
used to specify the line, so long as the number of collinear points along that line exceeds
the number of collinear points on any other line in the image. However, the non-linearity
of the parameters and the discretisation produce noisy accumulators. A major problem in
implementing the basic HT for lines is the definition of an appropriate accumulator space.
In application, Bresenham's line drawing algorithm (Bresenham, 1965) can be used to
draw the lines of votes in the accumulator space. This ensures that lines of connected votes
are drawn as opposed to use of Equation 5.27 that can lead to gaps in the drawn line. Also,
