Image Enhancement

HOMOMORPHIC FILTERING WITH THE

MULTIPLICATIVE IMAGE MODEL

f(x,y) = i(x,y) r(x,y)

i(x,y): illumination component (very low frequency);

r(x,y): reflectance component (medium-to-high frequency).

To separate the two components for filtering, take the logarithm:

Then, talking the Fourier transform, we get

Now, we may filter Z(u,v) with a linear filter (e.g., high-frequency

emphasis).

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