Counting pixels within a Region of Interest

[Claudia-2]

To Whom It May Concern,

I am completing a research project and would like to use ImageJ to digitally analyse photographs I have taken of grass samples. I need to be able to count the number of ‘yellow’, ‘green’ and total pixels for a Region of Interest.
The first step is to define the region of interest (ROI) which I have done manually.
The next step where I classify the pixels into colours and count them is where I am having difficult. I have thresholds already (Green: hue=56-110, saturation=10-250 and lightness=10-250) (Yellow: hue=16-55, saturation=10-250 and lightness=10-250), but I am unsure what tool/plugin will be useful in counting pixels. As I need to repeat this process for 400 photos I would like to make it as automated as possible.
Hopefully someone on the mailing list will be able to help me.

Regards,

Claudia Maynard


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[Lee Berndt]

Hi Claudia...I have a macro that determines green pixels/total pixels in turf....if you e-mail me at [hidden email] I'll forward it to you...
 
 

William L. Berndt, Ph.D.
239.246.0396
 
 

 
 
-----Original Message-----
From: Claudia <[hidden email]>
To: IMAGEJ <[hidden email]>
Sent: Sat, Mar 28, 2015 1:44 am
Subject: Counting pixels within a Region of Interest


To Whom It May Concern,

I am completing a research project and would like to
use ImageJ to digitally analyse photographs I have taken of grass samples. I
need to be able to count the number of ‘yellow’, ‘green’ and total pixels for a
Region of Interest.
The first step is to define the region of interest (ROI)
which I have done manually.
The next step where I classify the pixels into
colours and count them is where I am having difficult. I have thresholds already
(Green: hue=56-110, saturation=10-250 and lightness=10-250) (Yellow: hue=16-55,
saturation=10-250 and lightness=10-250), but I am unsure what tool/plugin will
be useful in counting pixels. As I need to repeat this process for 400 photos I
would like to make it as automated as possible.
Hopefully someone on the
mailing list will be able to help me.

Regards,

Claudia
Maynard


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ImageJ mailing list: http://imagej.nih.gov/ij/list.html

 

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[Michael Schmid]

On Sat, Mar 28, 2015 1:44 am Claudia wrote

> The next step where I classify the pixels into colours and count them is
where I am having difficult. I have thresholds already (Green:
hue=56-110, saturation=10-250 and lightness=10-250) (Yellow: hue=16-55,
saturation=10-250 and lightness=10-250), but I am unsure what
tool/plugin will be useful in counting pixels.

Hi Claudia,

for RGB images, Image>Adjust>Threshold (shift-T) calls the built-in
'Threshold Color' command. It can select a HSB range and create a
(somewhat lengthy) macro with the 'macro' button.

Michael

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