image convolution examples
Post on 08-Feb-2018
222 Views
Preview:
TRANSCRIPT
-
7/22/2019 Image Convolution Examples
1/7
Image convolution examplesByUtkarsh| Published: August 16, 2010
A convolution is very useful for signal processing in general. There is a lot of complex mathematical
theory available for convolutions. For digital image processing, you dont have to understand all of
that. You can use asimple matrix as an image convolution kerneland do some interesting things!
Simple box blurHeres a first and simplest. This convolution kernel has an averaging effect. So you end up with a
slight blur. The image convolution kernel is:
Note that the sum of all elements of this matrix is 1.0. This is important. If the sum is not exactly one,
the resultant image will be brighter or darker.
Heres a blur that I got on an image:
A simple blur done with convolutions
Gaussian blur
Gaussian blur has certain mathematical properties that makes it important for computer vision. And
you can approximate it with an image convolution. The image convolution kernel for a Gaussian blur
is:
http://www.aishack.in/2010/08/image-convolution-examples/http://www.aishack.in/author/admin/http://www.aishack.in/author/admin/http://www.aishack.in/author/admin/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/author/admin/http://www.aishack.in/2010/08/image-convolution-examples/ -
7/22/2019 Image Convolution Examples
2/7
Heres a result that I got:
Line detection with image convolutions
With image convolutions, you can easily detect lines. Here are four convolutions to detect horizontal,
vertical and lines at 45 degrees:
I looked for horizontal lines on the house image. The
result I got for this image convolution was:
-
7/22/2019 Image Convolution Examples
3/7
Edge detection
The above kernels are in a way edge detectors. Only thing is that they have separate components for
horizontal and vertical lines. A way to combine the results is to merge the convolution kernels. The
new image convolution kernel looks like this:
Below result I got with edge detection:
The Sobel Edge Operator
The above operators are very prone to noise. The Sobel edge operators have a smoothing effect, so
theyre less affected to noise. Again, theres a horizontal component and a vertical component.
On applying this image convolution, the result was:
-
7/22/2019 Image Convolution Examples
4/7
The laplacian operator
The laplacian is the second derivative of the image. It is extremely sensitive to noise, so it isnt used
as much as other operators. Unless, of course you have specific requirements.
Heres the result with the convolution kernel without diagonals:
The Laplacian of Gaussian
The laplacian alone has the disadvantage of being extremely sensitive to noise. So, smoothing the
image before a laplacian improves the results we get. This is done with a 55 image convolution
kernel.
-
7/22/2019 Image Convolution Examples
5/7
The result on applying this image convolution was:
Summary
You got to know about some important operations that can be approximated using an image
convolution. You learned the exact convolution kernels used and also saw an example of how each
operator modifies an image. I hope this helped!
Issues? Suggestions? Visit theGithub issue tracker for AI Shack
Back to top
Related Posts
1. Image Convolutions in OpenCV
2. Convolutions
3. The Sobel and Laplacian Edge Detectors
https://github.com/liquidmetal/aishack/issues/new?body=Related+page%3A+http%3A%2F%2Fwww.aishack.in%2F2010%2F08%2Fimage-convolution-examples%2Fhttps://github.com/liquidmetal/aishack/issues/new?body=Related+page%3A+http%3A%2F%2Fwww.aishack.in%2F2010%2F08%2Fimage-convolution-examples%2Fhttps://github.com/liquidmetal/aishack/issues/new?body=Related+page%3A+http%3A%2F%2Fwww.aishack.in%2F2010%2F08%2Fimage-convolution-examples%2Fhttp://www.aishack.in/2010/08/image-convolutions-in-opencv/http://www.aishack.in/2010/08/image-convolutions-in-opencv/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2011/04/the-sobel-and-laplacian-edge-detectors/http://www.aishack.in/2011/04/the-sobel-and-laplacian-edge-detectors/http://www.aishack.in/2011/04/the-sobel-and-laplacian-edge-detectors/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2010/08/image-convolutions-in-opencv/http://www.aishack.in/2011/04/the-sobel-and-laplacian-edge-detectors/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2010/08/image-convolutions-in-opencv/http://www.aishack.in/2011/04/the-sobel-and-laplacian-edge-detectors/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2010/08/image-convolutions-in-opencv/http://www.aishack.in/2011/04/the-sobel-and-laplacian-edge-detectors/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2010/08/image-convolutions-in-opencv/http://www.aishack.in/2011/04/the-sobel-and-laplacian-edge-detectors/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2010/08/image-convolutions-in-opencv/http://www.aishack.in/2011/04/the-sobel-and-laplacian-edge-detectors/http://www.aishack.in/2010/08/convolutions/http://www.aishack.in/2010/08/image-convolutions-in-opencv/https://github.com/liquidmetal/aishack/issues/new?body=Related+page%3A+http%3A%2F%2Fwww.aishack.in%2F2010%2F08%2Fimage-convolution-examples%2F -
7/22/2019 Image Convolution Examples
6/7
-
7/22/2019 Image Convolution Examples
7/7
Reply
2 Trackbacks
ByTubes UAS Grafcit | Grafika Citraon December 11, 2011 at 9:16 pm[...] Untuk image konvolutor, harapannya user bisa melakukan tersting terhadap inputan
matrix konvolusi seperti dicontohkan di situs ini :http://www.aishack.in/2010/08/image-
convolution-examples/[...] ByReaaliaikaista kuvanksittely OpenGL ES 2.0:lla | Mobiilikehityson March 12, 2012 at
7:48 pm
[...] Sample Convolution Kernels for Image Processing [...]
Post a Comment
Your email is neverpublished nor shared. Required fields are marked *
Name *
Email *
Website
Comment
You may use these HTML tags and attributes
http://www.aishack.in/2010/08/image-convolution-examples/?replytocom=3473#respondhttp://www.aishack.in/2010/08/image-convolution-examples/?replytocom=3473#respondhttp://grafcit.ittelkom.ac.id/?p=125http://grafcit.ittelkom.ac.id/?p=125http://grafcit.ittelkom.ac.id/?p=125http://www.aishack.in/2010/08/image-convolution-examples/http://www.aishack.in/2010/08/image-convolution-examples/http://www.aishack.in/2010/08/image-convolution-examples/http://www.aishack.in/2010/08/image-convolution-examples/http://mobiilikehitys.fi/reaaliaikaista-kuvankasittelya-opengl-es-2-0lla/http://mobiilikehitys.fi/reaaliaikaista-kuvankasittelya-opengl-es-2-0lla/http://mobiilikehitys.fi/reaaliaikaista-kuvankasittelya-opengl-es-2-0lla/http://mobiilikehitys.fi/reaaliaikaista-kuvankasittelya-opengl-es-2-0lla/http://www.aishack.in/2010/08/image-convolution-examples/http://www.aishack.in/2010/08/image-convolution-examples/http://grafcit.ittelkom.ac.id/?p=125http://www.aishack.in/2010/08/image-convolution-examples/?replytocom=3473#respond
top related