🚀 go-pugleaf

Hello

I am looking for some good image processing packages. Does anyone
know of any?

Thanks,

Steve

(reply to samsung@tigger.jvnc.net )

In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi (V{rri Alpo) writes:
>Harmonic distortion is nonlinear distortion characterized by the
>appearance in the output of harmonics other than the fundamental
>component when the input wave is sinusoidal.
>
>What is the name of the distortion which does not appear at the
>harmonic frequencies of the fundamental component but at some
>other frequencies?

Discordant distortion?  ;-)


--
Stan Reeves
Auburn University, Department of Electrical Engineering, Auburn, AL  36849
INTERNET: sjreeves@eng.auburn.edu

In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi (V{rri Alpo) writes:
| Harmonic distortion is nonlinear distortion characterized by the
| appearance in the output of harmonics other than the fundamental
| component when the input wave is sinusoidal.
| 
| What is the name of the distortion which does not appear at the
| harmonic frequencies of the fundamental component but at some
| other frequencies?

	Intermodulation

-- 
        carl lowenstein         marine physical lab     u.c. san diego
        {decvax|ucbvax} !ucsd!mpl!cdl                 cdl@mpl.ucsd.edu
                                                  clowenstein@ucsd.edu

>What is the name of the distortion which does not appear at the
>harmonic frequencies of the fundamental component but at some
>other frequencies? This type of distortion is often introduced
>by nonlinear filters.
----------

In a memoryless, non-time-varying analog system, driven by a sinusoid,
you cannot get distortion at frequencies at other than the harmonics
of the fundamental.  this is a direct result of the fact that any
memoryless nonlinear system can be represented by a taylor series expansion.

If the system has memory, you still cannot get signals at frequencies
other than harmonics. This comes from examining volterra series
expansions of such systems. 

If the system is time varying, or is a sampled system, one can get
either "mixing products" or "aliasing", so I guess the answer to your 
question is one of those terms. since this is a DSP group, I guess the
correct term is "aliasing".

varri@cs.tut.fi (V{rri Alpo) writes:

>Harmonic distortion is nonlinear distortion characterized by the
>appearance in the output of harmonics other than the fundamental
>component when the input wave is sinusoidal.

>What is the name of the distortion which does not appear at the
>harmonic frequencies of the fundamental component but at some
>other frequencies? This type of distortion is often introduced
>by nonlinear filters.

In RF work these are called "spurs", which is short for spurious
responses (or outputs).  You often find them at f+60Hz, f-60Hz,
f+-(twice the IF frequency), etc.  Sometimes they are considered
part of the "noise", even though they are correlated with the input.
In audio work you get "intermodulation distortion", where some
non-linearity produces sum and difference frequencies from two pure
tone inputs.  In digital work you get "aliasing".  For example, a
3 KHz square wave into a 44.1 KHz sampled system (say CDs) might
produce an 0.9 KHz output if the input filter was not good enough.
(From the 15th harmonic of the input aliased by the 44.1 KHz sampling
rate.)  I'm sure there are additional technical names, but most people who
work with them call them things that shouldn't be repeated around
small children.

-Lou Scheffer

In article <1088@chiton.ucsd.edu> cdl@chiton (Carl Lowenstein) writes:
|In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi (V{rri Alpo) writes:
|| Harmonic distortion is nonlinear distortion characterized by the
|| appearance in the output of harmonics other than the fundamental
|| component when the input wave is sinusoidal.
|| 
|| What is the name of the distortion which does not appear at the
|| harmonic frequencies of the fundamental component but at some
|| other frequencies?
|
|	Intermodulation
|


In the communication business, nonlinear distortion is is lumped together
under the term "Quantizing Noise". I know this is a misnomer but it is
the term used for this type of distortion.

In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi  writes:

>What is the name of the distortion which does not appear at the
>harmonic frequencies of the fundamental component but at some
>other frequencies? This type of distortion is often introduced
>by nonlinear filters.

I would call it parametric distortion or intermodulation i.e a
distortion due to the modulation of some transfer parameter of
the network by the signal being transferred.


Mike Gingell, Alcatel, Raleigh, NC USA  (919) 850-6444
UUCP:       ...!mcnc!aurgate!aurfs1!gingell
Internet:   gingell%aurfs1%aurgate@mcnc.org

In article <59881@aurs01.UUCP> gingell@aurw90.UUCP (Mike Gingell) writes:
>In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi  writes:
]>What is the name of the distortion which does not appear at the
]>harmonic frequencies of the fundamental component but at some
]>other frequencies? This type of distortion is often introduced
]>by nonlinear filters.
]
]I would call it parametric distortion or intermodulation i.e a
]distortion due to the modulation of some transfer parameter of
]the network by the signal being transferred.

In RF Engineering, intermodulation means the mixing of different
frequency components of a signal. This mixing occurs through ANY
nonlinearity in the system, and produces signals with frequency
components as follows:

   Fd =  nF1 +/- mF2

where n = 1....   and m = 1...

This can be derived by observing that the transfer function with a
nonlinearity can be represented by a power series:
   H = a + bf(x) + cf^2(x) ...

If one substitutes the fourier representation of the signal into
this, one ends up with terms where the signals are multiplied by
powers of each other. This yields the classic sum and difference
mixing formulae.

Note that a system with nonlinearities, if presented with a pure
sinusoid (single frequency signal), with produce only harmonic distortion.
It takes more than one frequency in the input in order to observe
intermodulation distortion.

-- 
John Moore HAM:NJ7E/CAP:T-Bird 381 {ames!ncar!noao!asuvax,mcdphx}!anasaz!john 
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