<< Chapter < Page
  Digital signal processing - dsp     Page 11 / 21
Chapter >> Page >

Call the inverseXform2D method

Then Listing 11 calls the inverseXform2D method to transform the complex wavenumber spectrum into a real space function. The inverseXform2D method requires the real and imaginary parts of the complex wavenumber spectrum as input parameters.

(Note that these are the original real and imaginary parts of the complex wavenumber spectrum. They are not the versions for which the originhas been shifted for display purposes.)

The inverseXform2D method also receives an incoming array object in which to store the real result of the transform process.

Display the result of the inverse transform

Finally, Listing 12 displays the result of the inverse transform as a surface in the space domain. This surface should compare favorably with the original surface that was transformed into the wavenumber domain in Listing 8

Listing 12. Display the result of the inverse transform.
new ImgMod29(recoveredSpatialData,3,false, displayType);

The output produced by Listing 12 is shown in the lower-left image in Figure 4 . Compare this with the input surface shown in the top-left image in Figure 4 . As you can see, they do compare favorably. In fact, they appear to be identicalin this grayscale plotting format. We will see later that when a more sensitive plotting format is used, small differences in the two may become apparent.

Display some numeric results

As discussed earlier, the code in Listing 13 samples and displays a few corresponding points on the original surface and the surface produced by theinverse transform process. The results can be used to evaluate the overall quality of the process as well as the correctness of the overall scaling.

Listing 13. Display some numeric results.
for(int row = 0;row<3;row++){ for(int col = 0;col<3;col++){ System.out.println(spatialData[row][col]+ " " + recoveredSpatialData[row][col] + " ");}//col }//row}//end main

Each line of output text contains two values, and ideally the two values should be exactly the same. Realistically, because of small computational errorsin the transform and inverse transform process, it is unlikely that the two values will be exactly the same except in computationally trivial cases. Unlessthe two values are very close, however, something probably went wrong in the transform process and the results should not be trusted.

Listing 13 also signals the end of the main method.

What do we know so far?

Now we know how to use the ImgMod30 class and the ImgMod29 class to:

  • Transform a purely real 3D surface from the space domain into the wavenumber domain
  • Transform a complex wavenumber spectrum into a purely real surface in the space domain
  • Shift the origin of the real, imaginary, and amplitude wavenumber spectral parts to convert the data into a format that is more suitable forplotting
  • Plot 3D surfaces in both domains

It is time to for us to take a look at the method named getSpatialData that can be used to create any of fourteen standard surfaces in the space domain.

Questions & Answers

I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
How can I make nanorobot?
Lily
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Digital signal processing - dsp. OpenStax CNX. Jan 06, 2016 Download for free at https://legacy.cnx.org/content/col11642/1.38
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Digital signal processing - dsp' conversation and receive update notifications?

Ask