Image Processing Reference
In-Depth Information
Fig. 11.12 The spherical transformation
Fig. 11.13 The ripple transformation
11.2.4 Ripple Transformation
Another interesting non-linear geometric mapping is the ripple transformation. It
distorts the image locally using a sinus function. The effect is that an overall wave
pattern is introduced to the image. The backward mapping for the ripple transfor-
mation is defined as
sin y ·
2 π
ω x
x +
a x ·
sin x ·
2 π
ω y
y +
a y ·
where a x and a y are the amplitudes of the wave pattern in the x- and y-directions,
respectively and ω x and ω y control the frequencies of the waves in the x- and y-
directions, respectively. In Fig. 11.13 the ripple transformation is illustrated.
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