measurement of green area (green pixels) in the digital camera images

[Hilal iLARSLAN]

 *Using Image J to quantify green pixels (plant leaves) using a digital
camera images





Hi everybody,



I need to measure the green area pixels (leaves) in the images.



 Can ImageJ do this?



If not which free programs would you recommend?





Thanks


Hilal

--

     **********************************
           Hilal Ilarslan, Ph.D
     Adjunct Assistant Professor

Department of Genetics, Development and Cell Biology
Iowa State University, Room 1 Bessey
Ames, Iowa  50011-1020 USA
[phone]        FAX: [phone]
email: [hidden email]
  http://www.gdcb.iastate.edu/
http://www.public.iastate.edu/~ihilal/

************************************
Sent from Ames, IA, United States

[Joachim Wesner]

Hi Hilal,

I think Imagej can certainly do this, however it depends what you mean by
"green" and what you mean by "area":

In the very simplest way you could seperate the green channel and measure
the number of pixels over a certain threshold or the integrated (average)
intensity.

However, as you will know, other colors as white and so on also have a
"green" content. If you really want the pixels that only belong to a
certain range of "green"
hue you will need some extra plugin for "color deconvolution" or the like
IIRC, I have  not yet used them.

And for the "area" you might probably  need to use one of the many plugin
that can generate (a) selection area(s), if you only need to count
connected parts starting
from a certain size.

It all depends on your problem, there will be no "fully automatic" way!

You my first thoughts!

Cheers


Mit freundlichen Grüßen / Best regards

Joachim Wesner




                                                                           
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 *Using Image J to quantify green pixels (plant leaves) using a digital
camera images


Hi everybody,

I need to measure the green area pixels (leaves) in the images.

 Can ImageJ do this?

If not which free programs would you recommend?




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[Justin McGrath-2]

I've used ImageJ to analyze leaf area from digital images.

Separating out the green channel does not work well, but as Joachim
suggested you can use hue. However, I've found that comparing the red and
blue channels to the green channel in a manner similar to NDVI works rather
well (leaves typically have very little red and only some blue), but
requires some adjustment between species. For soybean leaves I use

double red_add_blue = r*.6+b*.4;
double g_sub_rb = g-red_add_blue;
double g_add_rb = g+red_add_blue;
double mask = g_sub_rb/g_add_rb;

The higher the value, the more likely the pixel belongs to a leaf. You
didn't describe much about what you were doing, but typically lighiting is
very important. Even lighting produces much better results.

Justin

[David Webster]

Try Landini's "Threshold Color" plugin (see plugins page for download) with
the HSB button set. In my test case (i.e forest with trees, rocks, and
people) the leaves had very well defined green hue in ther hue histogram. I
think this is better than RGB as everything tends to have some green in it.

David Webster

On Thu, Aug 27, 2009 at 9:21 AM, Hilal iLARSLAN <[hidden email]> wrote:

>  *Using Image J to quantify green pixels (plant leaves) using a digital
> camera images
>
>
>
>
>
> Hi everybody,
>
>
>
> I need to measure the green area pixels (leaves) in the images.
>
>
>
>  Can ImageJ do this?
>
>
>
> If not which free programs would you recommend?
>
>
>
>
>
> Thanks
>
>
> Hilal
>
> --
>
>     **********************************
>           Hilal Ilarslan, Ph.D
>     Adjunct Assistant Professor
>
> Department of Genetics, Development and Cell Biology
> Iowa State University, Room 1 Bessey
> Ames, Iowa  50011-1020 USA
> [phone]        FAX: [phone]
> email: [hidden email]
>  http://www.gdcb.iastate.edu/
> http://www.public.iastate.edu/~ihilal/
>
> ************************************
> Sent from Ames, IA, United States
>