android图像处理之图像二值化

最新推荐文章于 2022-10-08 14:21:57 发布

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最新推荐文章于 2022-10-08 14:21:57 发布

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本文链接：https://blog.youkuaiyun.com/ggtaas/article/details/8179986

本文详细介绍了如何使用ColorMatrix将图像灰度化，并通过调整阈值进行二值化处理，实现图像的简单二值化效果。通过实例代码演示了整个过程，包括图像灰度化、二值化及展示步骤。

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package com.scy.binaryzation2;

import javax.security.auth.PrivateCredentialPermission;

import android.os.Bundle;
import android.app.Activity;
import android.app.PendingIntent.CanceledException;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.Paint;
import android.view.Menu;
import android.widget.ImageView;

/**
 * 首先通过ColorMatrix将图像灰度化，在通过获取图像的灰度值并依次更改RGB的值获得二值化图像
 * @author scy
 * 二值化图像的阈值，在本程序中经过测试，选取160，这个阈值根据不同的图像会有不同的取值。这个可以
 * 通过对图像颜色分布的分析获知大概的区间。也可以同相关的算法计算得出。
 *
 */
public class MainActivity extends Activity 
{
	private ImageView imageView;
	private Bitmap bitmap,bitmap2,bitmapBina;
	private ColorMatrix colorMatrix;
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
        bitmap2 = convert2Gray(bitmap);
        bitmapBina = binaryzation(bitmap2);        
        
        imageView = (ImageView)findViewById(R.id.image);
        imageView.setImageBitmap(bitmapBina);  
        
    }

	public Bitmap convert2Gray(Bitmap bitmap3)
	{
		colorMatrix = new ColorMatrix();
		colorMatrix.setSaturation(0);
		ColorMatrixColorFilter filter = new ColorMatrixColorFilter(colorMatrix);
		
		Paint paint = new Paint();
		paint.setColorFilter(filter);
		Bitmap result = Bitmap.createBitmap(bitmap3.getWidth(), bitmap3.getHeight(), Config.ARGB_8888);
		Canvas canvas = new Canvas(result);
		
		canvas.drawBitmap(bitmap3, 0, 0, paint);
		return result;
	}
	
	private Bitmap binaryzation(Bitmap bitmap22)
	{
		//bitmapBina = bitmap22.copy(Config.ARGB_8888, true);
		int width = bitmap22.getWidth();
		int height = bitmap22.getHeight();
		for (int i = 0; i < width; i++)
		{
			for (int j = 0; j < height; j++)
			{
				int col = bitmap22.getPixel(i, j);
				int alpha = col&0xFF000000;
                int red = (col&0x00FF0000)>>16;
                int green = (col&0x0000FF00)>>8;
                int blue = (col&0x000000FF);
                //用公式X = 0.3×R+0.59×G+0.11×B计算出X代替原来的RGB
                int gray = (int)((float)red*0.3+(float)green*0.59+(float)blue*0.11);
                
				if (gray<=160)
				{
					gray = 0;
				}
				else
				{
					gray = 255;
				}
                //新的ARGB
                int newColor = alpha|(gray<<16)|(gray<<8)|gray;               

				bitmap22.setPixel(i, j, newColor);
			}
		}		
		return bitmap22;
	}
}