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Image Processing with ImageJ - Second Edition

You're reading from   Image Processing with ImageJ - Second Edition Extract and analyze data from complex images with ImageJ, the world's leading image processing tool

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Product type Paperback
Published in Nov 2015
Publisher
ISBN-13 9781785889837
Length 256 pages
Edition 1st Edition
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Authors (2):
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Jurjen Broeke Jurjen Broeke
Author Profile Icon Jurjen Broeke
Jurjen Broeke
 Pascau Pascau
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Pascau
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Table of Contents (17) Chapters Close

Image Processing with ImageJ Second Edition
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
1. Getting Started with ImageJ FREE CHAPTER 2. Basic Image Processing with ImageJ 3. Advanced Image Processing with ImageJ 4. Image Segmentation and Feature Extraction with ImageJ 5. Basic Measurements with ImageJ 6. Developing Macros in ImageJ 7. Explanation of ImageJ Constructs 8. Anatomy of ImageJ Plugins 9. Creating ImageJ Plugins for Analysis 10. Where to Go from Here? Index

Feature extraction


As we saw in the earlier sections, filters can be used to isolate different frequencies using filters. By convolving an image with a Mexican hat filter, high frequencies are preserved, while using the box filter has the opposite effect. The difference between the filters in this section and the filters in the previous section is in specificity. The Mexican hat filter had no preference for direction. When there was an edge with sharp contrast (quick change in intensity), the filter had a strong effect. However, sometimes, you are only interested in a specific type of edge. Let's assume that we only want to detect vertical edges. The Mexican hat filter will give us all the edges in all directions, not just the vertical ones. This will be the topic of the following section.

Edge detection

To detect only vertical edges, we need to create a kernel that emphasizes pixels that are in a vertical orientation. The following kernels can detect different orientations of edges:

To perform...

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