如何测量背景上彩色区域的百分比？图片J？

Question

我想测量这张灰色地图的紫色区域百分比。

我可以粗略地说代表10%的面积，但我需要一个确切的值。

我知道有一个名为 ImageJ 的免费工具，但我不知道如何使用它。

也许你可以建议我使用其他工具或如何执行此类任务。

提前致谢。

Answer 1

您可以为该任务编写一个小的 ImageJ 插件：

import ij.gui.DialogListener;
import ij.gui.GenericDialog;
import ij.plugin.filter.ExtendedPlugInFilter;
import ij.plugin.filter.PlugInFilterRunner;
import ij.process.ImageProcessor;
import ij.IJ;
import ij.ImagePlus;
import java.awt.AWTEvent;
import java.awt.Label;
import java.lang.Math;

public class Purple_Counter implements ExtendedPlugInFilter, DialogListener{
    private final int FLAGS = DOES_RGB | PARALLELIZE_STACKS;
    private boolean preview = true;
    private ImagePlus im;
    private int count;
    private double total;
    private int color = 0xff64318a;
    private int background = 0xffd7d7d7;
    private double maxDistanceColor;
    private double maxDistanceBckg ;

    public int setup(String args, ImagePlus im){
        this.im = im;
        maxDistanceColor = 60;
        maxDistanceBckg = 60;
        return FLAGS;
    }

    public void run(ImageProcessor ip){
        int height = ip.getHeight();
        int width = ip.getWidth();
        count = 0;
        total = 0;
        for(int a = 0; a < height; a++){
            for(int b = 0; b < height; b++){
                int p = ip.getPixel(a,b);
                if ( calculateDistance(p,color) < maxDistanceColor){
                    count++;
                    ip.putPixel(a,b,0xffff0000);
                }
                if ( calculateDistance(p,background) < maxDistanceBckg){
                    total++;
                    ip.putPixel(a,b,0xff000000);
                }
            }
        }
        IJ.log("Counted: " + count + "| Total: " + total);
        IJ.log("Percentage: " +  (count/total) * 100f);
        IJ.log("");
    }

    private double calculateDistance(int color1, int color2){
        int red1 = (color1 >> 16)&0xff;
        int red2 = (color2 >> 16)&0xff;
        int green1 = (color1 >> 8)&0xff;
        int green2 = (color2 >> 8)&0xff;
        int blue1 = color1 & 0xff;
        int blue2 = color2 & 0xff;
        double distance = Math.sqrt((red1 * red1 - 2*red1*red2 + red2*red2) + (green1 * green1 - 2*green1*green2 + green2*green2) + (blue1 * blue1 - 2*blue1*blue2 + blue2*blue2));
        return distance;
    }

    public int showDialog(ImagePlus imp, String Command, PlugInFilterRunner pfr){
        //Dialog to control the used color distances
        GenericDialog gd = new GenericDialog("Distance Settings");
        gd.addMessage("Please chose maximal distances to identify POI and background pixels: ");
        gd.addSlider("POI Red: ", 0,255,0x64);
        gd.addSlider("POI Green: ", 0,255,0x31);
        gd.addSlider("POI Blue: ", 0,255,0x8a);
        gd.addSlider("BCKG Red: ", 0,255,0xd7);
        gd.addSlider("BCKG Green: ", 0,255,0xd7);
        gd.addSlider("BCKG Blue: ", 0,255,0xd7);
        gd.addSlider("POI max. Distance: ", 0.001, 1000, maxDistanceColor);
        gd.addSlider("BCKG max. Distance: ", 0.001, 1000, maxDistanceBckg);
        gd.addPreviewCheckbox(pfr, "Preview");
        gd.addDialogListener(this);
        gd.showDialog();

        if(gd.wasCanceled() ||!dialogItemChanged(gd, null)){
            return DONE;
        }
        return IJ.setupDialog(imp, FLAGS);
    }

    public boolean dialogItemChanged(GenericDialog gd, AWTEvent e){
        int alpha = 0xff;
        int colorRed = (int)gd.getNextNumber();
        int colorGreen = (int)gd.getNextNumber();
        int colorBlue = (int)gd.getNextNumber();
        int bckgRed = (int)gd.getNextNumber();
        int bckgGreen = (int)gd.getNextNumber();
        int bckgBlue = (int)gd.getNextNumber();
        color = (alpha << 24 | colorRed << 16 | colorGreen << 8 | colorBlue);
        background = (alpha << 24 | bckgRed << 16 | bckgGreen << 8 | bckgBlue);
        maxDistanceColor = gd.getNextNumber();
        maxDistanceBckg = gd.getNextNumber();
        return true;
    }

    public void setNPasses(int nPasses){
        //Has to be implemented for ExtendedPlugInFilter
    }
}

此插件将打开以下对话框：

此对话框允许设置感兴趣像素 (POI) 颜色和背景 (bckg) color.Via 手动设置距离，可以决定插件将什么确定为 POI 或背景。参考颜色如下：

兴趣点：

背景：

为了验证您使用的距离设置是否正确，我建议使用预览功能。在使用它时，ImageJ 会将它认为是 POI 的每个像素着色为红色，而每个背景像素都将着色为黑色。我使用对话框中给出的设置得到以下结果：

如您所见，由于伪影，一些白色像素也被视为背景。文本也被视为背景，所以我建议在使用插件之前将其删除。如果去掉它，结果会稍微变化到 4.2% 左右。

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