Set ROI on image with OpenCV

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HI Everyone!

I am working in image processing and in this field of programming i am a beginner.
I wanna detect rectangel on picture i am using openCV librarys and C++.
How can i set a ROI on image, with Opencv, if i have white background and about in the center of image i have an rectangle with black background.
The image size is(800*600px) and the rectangel's size (150*150px);
I dont know exactly where is that rectangle in image.
This is a gray scaled image.

Thank you advance!

Posted 28-Apr-12 21:54pm

nagyervin89

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Comments

Sergey Alexandrovich Kryukov 29-Apr-12 17:54pm

And ROI is?.. Return Of Investment? Rate Of Return? Royal Institute of Oil Painters? Risk Of Infection? :-)
--SA

BupeChombaDerrick 29-Apr-12 18:49pm

ROI is Region Of Interest. Anyways who knows exactly what it means here in the question :-)

Sergey Alexandrovich Kryukov 29-Apr-12 22:43pm

Thank you very much. Anyway, abbreviations is evil in most cases, and using this one makes a question not quite valid.
--SA

BupeChombaDerrick 30-Apr-12 8:22am

you are welcome.

2 solutions

Solution 1

Are you asking for an algorithm to detect a rectangle or how to set and unset Region of Interest(ROI)?

use

C++

cvSetImageROI(img,cvRect(x,y,width,height));

to set ROI where img = image, x,y are anchor points for the rectangle

and

C++

cvResetImageROI(img);

to unset ROI

Then all processing will take place within the specified region of interest (ROI).

Hope this helps

Posted 29-Apr-12 12:45pm

BupeChombaDerrick

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

jk chan · Accepted Answer · 2012-04-29T18:52:00

Solution 2

you can use Hough Transform to detect rectangles. see http://www.google.co.in/url?sa=t&rct=j&q=detecting%20rectangle%20with%20hough%20transform&source=web&cd=4&ved=0CEcQFjAD&url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload%3Fdoi%3D10.1.1.59.4239%26rep%3Drep1%26type%3Dpdf&ei=thmeT8q-OMbMrQeOi9Vr&usg=AFQjCNH3Ar8j1qq5aeOtKD2fPLNOunub9A&cad=rja[^]

Posted 29-Apr-12 18:52pm

jk chan

Comments

BupeChombaDerrick 30-Apr-12 8:31am

thumbs up

jk chan 30-Apr-12 8:35am

:)

Set ROI on image with OpenCV

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Solution 1

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Set ROI on image with OpenCV

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