Display the original image (map-roi.viff and its
Fourier Transform.
Create the image expanded by 4, without any interpolation:
Resample the image by 4 using a
pixel replication interpolation method.
Create a grid image with impulses spaced by 4 using the
Impulse operator.
Multiply the grid image to the expanded image to obtain the
image geometrically expanded by 4, with no interpolation.
Take and display the DFT of the expanded image.
Implement the spatial domain interpolation using convolution and
the following kernels:
Zero order interpolation: use the
Constant to build
a 4x4 kernel with constant 1
Bilinear interpolation: multiply two
Piecewise Linear operators
both generating an image of
size 9x9, from values ranging from 0 to 1 and the following
parameters
Period: 9
Rise Time: 4
Fall Time: 4
Pulse Width:0
for X in one image and for Y in the other image.
Implement the frequency domain interpolation using
FFT
and the following frequency filters,
using the operator
Low-Pass
Ideal filtering:
Butterworth filtering, order 3
Exercises
What is the cutoff frequency of the filters as function of the
scaling factor?
What is the result if we expand the DFT of the original image
using pixel replication algorithm and take the inverse DFT?
Use the expand property of the DFT and the convolution theorem
to explain the results.