Microscopy Primer
Light and Color
Microscope Basics
Special Techniques
Digital Imaging
Confocal Microscopy
Live-Cell Imaging
Photomicrography
Microscopy Museum
Virtual Microscopy
Fluorescence
Web Resources
License Info
Image Use
Custom Photos
Partners
Site Info
Contact Us
Publications
Home

The Galleries:

Photo Gallery
Silicon Zoo
Pharmaceuticals
Chip Shots
Phytochemicals
DNA Gallery
Microscapes
Vitamins
Amino Acids
Birthstones
Religion Collection
Pesticides
BeerShots
Cocktail Collection
Screen Savers
Win Wallpaper
Mac Wallpaper
Movie Gallery

Filtering Periodic Noise: Removal of Interference and Halftone Patterns

Periodic noise, arising from vibration, electronic interference, halftone printing, fluorescent lighting, or other causes is difficult or impossible to remove with neighborhood operations in the spatial or pixel domain, because it extends throughout the image. However, transforming the image to the Fourier or frequency domain often facilitates its removal. This interactive Java tutorial illustrates the removal of electronic interference and halftone patterns. The Fourier transform power spectrum of the noisy image shows spikes (bright points indicating specific noise frequencies). Creating a mask to remove those spikes may be done either manually or using processing tools that will be introduced later on, applied to the image of the power spectrum itself. Once the spikes are removed, transforming the image back to the pixel domain recovers the image with the noise suppressed or removed.

Interactive Java Tutorial
ATTENTION
Our servers have detected that your web browser does not have the Java Virtual Machine installed or it is not functioning properly. Please install this software in order to view our interactive Java tutorials. You may download the necessary software by clicking on the "Get It Now" button below.

 

The tutorial initializes with a randomly selected specimen appearing in the Specimen Image window. The Choose A Specimen pull-down menu provides a selection of specimen images, in addition to the initial randomly chosen one. The radio buttons show the Original image, the Fourier transform Power Spectrum, the Mask that can remove the spikes due to the periodic noise, the Masked Power Spectrum with those spikes removed, and the Filtered Image after an inverse Fourier transform is applied.

Contributing Authors

John C. Russ - Materials Science and Engineering Dept., North Carolina State University, Raleigh, North Carolina, 27695.

Matthew Parry-Hill, and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.


BACK TO INTRODUCTION TO DIGITAL IMAGE PROCESSING AND ANALYSIS

BACK TO MICROSCOPY PRIMER HOME

Questions or comments? Send us an email.
© 1998-2009 by Michael W. Davidson, John Russ, Olympus America Inc., and The Florida State University. All Rights Reserved. No images, graphics, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last modification: Wednesday, Mar 26, 2014 at 01:23 PM
Access Count Since July 20, 2006: 4168
For more information on microscope manufacturers,
use the buttons below to navigate to their websites: