Area fraction in colored image

[shubham1278]

<http://imagej.1557.x6.nabble.com/file/t382412/1.jpg>
Hi,

I want to find the area fraction of blue, red, gold and gray color in the
attached image. I am choosing HSB color space in Color Threshold method to
identify them. I am using the values of Hue as 0-24 for Red, 24-44 for Gold
and 44-150 for Blue colors. But I don't understand how to find the area of
gray color in this image. Moreover, the gray color gets included in Hue
24-44, i.e., gold color.



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[Krs5]

Without trying but maybe the colorsegmentation plugin can do the job
(http://bigwww.epfl.ch/sage/soft/colorsegmentation/)?

Best wishes

Kees


Dr Ir K.R. Straatman
Senior Experimental Officer
Advanced Imaging Facility
Centre for Core Biotechnology Services
University of Leicester
www.le.ac.uk/advanced-imaging-facility




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[Jeremy Adler]

Part of the problem is that grey isn't a colour, therefore it cannot be selected by Hue.
Grey is an equivalence of the Red, Green and Blue components - you need to decide how equivalent.
Which parts of an image appear grey also depends on the camera settings and the illumination - has the white balance been set.

Your definition of grey is critical - maybe that the three RGB intensities are within 10% of each other.
Starting with the Red image you can calculate the difference of the Blue and Green images from the sum of Red and the second colour
(Red - Green)/(Red + Green)    and  (Red - blue)/(Red + Blue)

Then threshold, maybe -0.1 to 0.1, these two images,
producing two binary images.
Finally combine the two binary images with AND to find the pixels that meet the criteria for the 3 colour
Grey pixels.
The definition of grey as an equivalence of the RGB intensities will include matching low values - blackish
Excluding them should be quite easy.

run("Duplicate...", " ");
title=getTitle();
run("Add...", "value=1");// ensure all values >zero
run("Split Channels");
Red=title+" (red)";
selectImage(Red);
rename("Red");
Green=title+" (green)";
selectImage(Green);
rename("Green");
Blue=title+" (blue)";
selectImage(Blue);
rename("Blue");
run("Image Expression Parser (Macro)", "expression=(A-B)/(A+B) a=Red b=Green c=None");
rename("RedGreen");
run("Image Expression Parser (Macro)", "expression=(A-B)/(A+B) a=Red b=Blue c=None d=None");
rename("RedBlue");

// threshold
Tval=0.08;// threshold
selectImage("RedGreen");
setThreshold(-Tval, Tval);
run("Make Binary");
rename("RedGreenBin");
selectImage("RedBlue");
setThreshold(-Tval, Tval);
run("Make Binary");
rename("RedBlueBin");
imageCalculator("AND create", "RedGreenBin","RedBlueBin");

Jeremy Adler
BioVis
Uppsala





-----Original Message-----
From: ImageJ Interest Group <[hidden email]> On Behalf Of shubham1278
Sent: den 6 augusti 2019 00:07
To: [hidden email]
Subject: Area fraction in colored image

<http://imagej.1557.x6.nabble.com/file/t382412/1.jpg>
Hi,

I want to find the area fraction of blue, red, gold and gray color in the attached image. I am choosing HSB color space in Color Threshold method to identify them. I am using the values of Hue as 0-24 for Red, 24-44 for Gold and 44-150 for Blue colors. But I don't understand how to find the area of gray color in this image. Moreover, the gray color gets included in Hue 24-44, i.e., gold color.



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[Kenneth Sloan-2]

Perhaps this will help.  It's crude, and needs to be adapted to your particular needs, but perhaps it's a useful starting point.

// File: ListColors.java                                                                                                                
// Author: K R Sloan                                                                                                                    
// Last Modified: 7 August 2019                                                                                                        
// Purpose: list colors in an image                                                                                            
import ij.*;
import ij.plugin.*;
import ij.process.*;
import java.awt.*;
import java.util.*;
public class ListColors implements PlugIn
{
    public void run(String arg)
    {
        ImagePlus ipl = IJ.getImage();
        ImageProcessor ip = ipl.getProcessor();
        ColorProcessor cp = (ColorProcessor)ip.convertToRGB();
        listColors(cp);
    }
    private class ColorNumber implements Comparable<ColorNumber>
    {
        private Color color;
        private long count;
        public Color getColor(){return this.color;}
        public long  getCount(){return this.count;}
        public ColorNumber(Color color, int count)
        {
            this.color = color;
            this.count = count;
        }
        public void increment()
        {
            this.count++;
        }
        public int compareTo(ColorNumber other)
        {
            if(this.count < other.count) return -1;
            if(this.count > other.count) return 1;
            else return 0;
        }
        public String toString()
        {
            String result = "[" + this.color + ", " + this.count + "]";
            return result;
        }
    }
    public void listColors(ColorProcessor cp)
    {
      ArrayList<ColorNumber> cNAL = new ArrayList<ColorNumber>();
        int width = cp.getWidth();
        int height = cp.getHeight();
        for(int yPix=0;yPix<height;yPix++)
            for(int xPix=0;xPix<width;xPix++)
                {
                    Color color = cp.getColor(xPix,yPix);
                    tally(cNAL, color);
                }
        Collections.sort(cNAL);
        for(int i=cNAL.size()-1;i>=0;i--)
            {
                IJ.log("ListColors: " + cNAL.get(i));
            }
    }
    private void tally(ArrayList<ColorNumber> cNAL, Color color)
    {
        for(int i=0;i<cNAL.size();i++)
            {
                ColorNumber cn = cNAL.get(i);
                if(color.equals(cn.getColor()))
                    { // found                                                                                                          
                        cn = cNAL.remove(i);
                        cn.increment();
                        cNAL.add(0,cn);
                        return;
                    }
            }
        // not found                                                                                                                    
        cNAL.add(0, new ColorNumber(color,1));
    }
}



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Kenneth Sloan
[hidden email]
Vision is the art of seeing what is invisible to others.



 
> Hi,
>
> I want to find the area fraction of blue, red, gold and gray color in the attached image.  

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