The frequency domain plays an important role in image
processing to smooth, enhance, and detect edges of images. Although
image data typically does not include imaginary values, the fast Fourier
Transform (FFT) has been used for obtaining spectra. In this paper,
the fast Hartley Transform (FHT) is used to Transform two-dimensional
image data. Because the Hartley Transform is real valued, it does
not require complex operations. Both spectra and autocorrelations of
two-dimensional ultrasound images of normal and abnormal livers were
computed.
An important book that cover wavelet domain. It help a lot in understanding wavelets and their applications.
Beside explanations of the Transform and application of this, there are also presents the reasons why wavelets are better than Fourier Transform.
NN Functions
a program in Lisp to demonstrate working of an artificial neuron. (Enter an input vector X and weight vector W. Calculate weighted sum XW. Transform this using signal or activation functions like logistic, threshold, hyperbolic-tangent, linear, exponential, sigmoid or some other functions (syntax provided) and display the output).
Abstract - A fl exible multiscale and directional representation for images is
proposed. The scheme combines directional fi lter banks with the
Laplacian pyramid to provides a sparse representation for two-
dimensional piecewise smooth signals resembling images. The
underlying expansion is a frame and can be designed to be a
tight frame. Pyramidal directional fi lter banks provide an effective
method to implement the digital curvelet Transform. The regularity
issue of the iterated fi lters in the directional fi lter bank is examined.
Main program running when workpiece is ready on deferent belt(deferent_ready=ture).
* Call Square_Wave subroutine to generate 0.5ms square wave on P1.2 to drive
* electromotor,then drive deferent belt step forward. When it steps to the measure
* zone, it stops to be measured. Then call A_D subroutine to Transform analog
* signals to digital signals , after then call serial subroutine to transfer
* digital signals to PC. Call square wave subroutine to drive deferent belt step to
* original position waitting for defere ready flag to run the next circle.
Use
the fast Fourier Transform function fft to analyse following signal. Plot the original signal, and the magnitude of its
spectrum linearly and logarithmically. Apply Hamming window to reduce the
leakage.
.
The hamming window can be coded in Matlab as
for n=1:N
hamming(n)=0.54+0.46*cos((2*n-N+1)*pi/N);
end;
where
N is the data length in the FFT.
