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Re: Finding area of a triangle shape within a complex image of a single color

Posted by Olivier Burri on Jul 25, 2013; 8:10am
URL: http://imagej.273.s1.nabble.com/Finding-area-of-a-triangle-shape-within-a-complex-image-of-a-single-color-tp5004059p5004131.html

Hi there,

Maybe you could use a k-means clustering algorithm to put together all objects of the same color. Then you could easily threshold and count them.

Of course, without seeing the actual image, I cannot say whether it will work.

Best,

Oli

Olivier Burri
Engineer - Image Processing
& Software Development
EPFL - SV - PTECH - PTBIOP


-----Original Message-----
From: ImageJ Interest Group [mailto:[hidden email]] On Behalf Of Johannes Schindelin
Sent: lundi 22 juillet 2013 17:02
To: [hidden email]
Subject: Re: Finding area of a triangle shape within a complex image of a single color

Hi Tony,

On Sat, 20 Jul 2013, Burinok wrote:

>    I have been searching for a way to find the area of a piece of an
> object in imageJ. Unfortunately, there is no contrast difference to be used.

In your example, there is quite a clear contrast between blue (foreground0 and white (background)... what do your *real* images look like?

> I attach an example that I drew up in powerpoint here. The goal would
> be to find the area of the triangle on the left.

Note that there is also a triangle on the right, even if its upper and lower corners do not extend beyond the middle rectangle.

> I have not come across any solutions that could do it if the object
> was all of a single color. Does anyone have any suggestions?

Traditionally, ImageJ's strength lies in bio-medical image processing applications, and this one strikes me more like a traditional, industrial machine vision problem.

Having said that, if a real big (but simple) hammer fits your needs, you could implement a custom Hough transform that identifies triangles.

Ciao,
Johannes

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