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Harris corner values

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donny008

Harris corner values

Hello all

I used the plugin form the website http://www.imagingbook.com/index.php?id=98 for the harris corner detector in imagej

and once i run i am able to detect corners. all i get is a brightened image. the values include alpha, threshold and max. points i am assuming this is due to the wrong values that i gave.could be also something silly than i think. could someone guide me with the right values so as to get the desired result.

Burger Wilhelm

Re: Harris corner values

Hello Donny George,

the default settings (for 8-bit gray images) for the plugin's dialog are obtained from class HarrisCornerDetector (in package harris):

DEFAULT_ALPHA = 0.050f;
DEFAULT_THRESHOLD = 20000;

The resulting image is a brightened (contrast-reduced) copy of the input image and the detected corners should be marked by black crosses.

Did you try the default settings and/or which values did you enter?
Does your image contain any corners at all?

--
Wilhelm

________________________________________
From: ImageJ Interest Group [[hidden email]] On Behalf Of Donny George [[hidden email]]
Sent: Sunday, June 20, 2010 09:47
To: [hidden email]
Subject: Harris corner values

Hello all

I used the plugin form the website http://www.imagingbook.com/index.php?id=98 for the harris corner detector in imagej

and once i run i am able to detect corners. all i get is a brightened image. the values include alpha, threshold and max. points i am assuming this is due to the wrong values that i gave.could be also something silly than i think. could someone guide me with the right values so as to get the desired result.

donny008

Re: Harris corner values

Hello Wilhelm

thanks for the response. indeed i did try the default values of the program
which where

DEFAULT_ALPHA = 0.05
DEFAULT_THRESHOLD = 20000

i also tried the values which you gave and many other values as trial and
error. i am sure my images does have corners. as part of the result i only
obtain the brightened image but no corners are marked i tried different
images. my images are those of solar wafers and i have attached one for your
reference. i would be really thankful if you could give some inputs so as to
detect corners from my image.

thnks
don

On Sun, Jun 20, 2010 at 10:13 AM, Burger Wilhelm <
[hidden email]> wrote:

> Hello Donny George,
>
> the default settings (for 8-bit gray images) for the plugin's dialog are
> obtained from class HarrisCornerDetector (in package harris):
>
> DEFAULT_ALPHA = 0.050f;
> DEFAULT_THRESHOLD = 20000;
>
> The resulting image is a brightened (contrast-reduced) copy of the input
> image and the detected corners should be marked by black crosses.
>
> Did you try the default settings and/or which values did you enter?
> Does your image contain any corners at all?
>
> --
> Wilhelm
>
> ________________________________________
> From: ImageJ Interest Group [[hidden email]] On Behalf Of Donny
> George [[hidden email]]
> Sent: Sunday, June 20, 2010 09:47
> To: [hidden email]
> Subject: Harris corner values
>
> Hello all
>
> I used the plugin form the website
> http://www.imagingbook.com/index.php?id=98 for the harris corner detector
> in imagej
>
> and once i run i am able to detect corners. all i get is a brightened
> image. the values include alpha, threshold and max. points i am assuming
> this is due to the wrong values that i gave.could be also something silly
> than i think. could someone guide me with the right values so as to get the
> desired result.
>

--
Donny George

Burger Wilhelm

Re: Harris corner values

For this I would need to have your image at hands. The ImageJ mailer strips off any attachments.

--
Wilhelm

________________________________________
From: ImageJ Interest Group [[hidden email]] On Behalf Of Donny George [[hidden email]]
Sent: Sunday, June 20, 2010 11:58
To: [hidden email]
Subject: Re: Harris corner values

Hello Wilhelm

thanks for the response. indeed i did try the default values of the program
which where

DEFAULT_ALPHA = 0.05
DEFAULT_THRESHOLD = 20000

i also tried the values which you gave and many other values as trial and
error. i am sure my images does have corners. as part of the result i only
obtain the brightened image but no corners are marked i tried different
images. my images are those of solar wafers and i have attached one for your
reference. i would be really thankful if you could give some inputs so as to
detect corners from my image.

thnks
don

On Sun, Jun 20, 2010 at 10:13 AM, Burger Wilhelm <
[hidden email]> wrote:

--
Donny George

donny008

Re: Harris corner values

Hello

Finally the images work with help from wilhelm by enhancing the contrast. However i would like to know if there is some way to avoid certain specific shapes corresponding to quadrilaterals or polygons from being displayed as corners. Could i use area as a property to eliminate these structures ?

thnks
don