android 将图片转换成黑白图片

短命女 2022-08-14 04:39 529阅读 0赞

先调用android的系统工具，获取图片生成bitmap文件，再使用android中的二值化技术，将图片转化成黑白图片，主界面代码：

package com.example.blackwhite;
    
    import java.io.IOException;
    
    import android.media.ThumbnailUtils;
    import android.net.Uri;
    import android.os.Bundle;
    import android.provider.MediaStore;
    import android.app.Activity;
    import android.content.ContentResolver;
    import android.content.Intent;
    import android.database.Cursor;
    import android.graphics.Bitmap;
    import android.graphics.Bitmap.Config;
    import android.util.Log;
    import android.view.Menu;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    import android.widget.ImageView;
    import android.widget.TextView;
    
    public class MainActivity extends Activity {
    	private final String IMAGE_TYPE = "image/*";
    
    	private final int IMAGE_CODE = 0; // 这里的IMAGE_CODE是自己任意定义的
    
    	private Button addPic = null;
    
    	private ImageView imgShow = null;
    
    	private TextView imgPath = null;
    
    	@Override
    	public void onCreate(Bundle savedInstanceState) {
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity_main);
    		init();
    	}
    
    	private void init() {
    		// TODO Auto-generated method stub
    
    		addPic = (Button) findViewById(R.id.btn_add);
    		imgPath = (TextView) findViewById(R.id.img_path);
    		imgShow = (ImageView) findViewById(R.id.imgShow);
    		addPic.setOnClickListener(listener);
    
    	}
    
    	private OnClickListener listener = new OnClickListener() {
    
    		@Override
    		public void onClick(View v) {
    			// TODO Auto-generated method stub
    
    			Button btn = (Button) v;
    
    			switch (btn.getId()) {
    
    			case R.id.btn_add:
    				setImage();
    				break;
    			}
    
    		}
    
    		private void setImage() {
    			// TODO Auto-generated method stub
    			// 使用intent调用系统提供的相册功能，使用startActivityForResult是为了获取用户选择的图片的地址
    			Intent getAlbum = new Intent(Intent.ACTION_GET_CONTENT);
    			getAlbum.setType(IMAGE_TYPE);
    			startActivityForResult(getAlbum, IMAGE_CODE);
    		}
    	};
    
    	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    
    		//  RESULT_OK 是系统自定义得一个常量
    		if (resultCode != RESULT_OK) { 
    			Log.e("onActivityResult", "返回的resultCode出错");
    			return;
    		}
    
    		Bitmap bm = null;
    
    		// 外界的程序访问ContentProvider所提供数据 可以通过ContentResolver接口
    		ContentResolver resolver = getContentResolver();
    
    		// 判断接收的Activity是不是选择图片的
    		if (requestCode == IMAGE_CODE) {
    
    			try {
    				// 获得图片的地址Uri
    				Uri originalUri = data.getData(); 
    				//根据图片的URi生成bitmap
    				bm = MediaStore.Images.Media.getBitmap(resolver, originalUri);
    				//将图片转化成黑白图片
    				bm =convertToBlackWhite(bm);
    				//显得到bitmap图片
    				imgShow.setImageBitmap(bm);
    
    				// 新建一个字符串数组用于存储图片地址数据。
    				String[] proj = { MediaStore.Images.Media.DATA };
    
    				// android系统提供的接口，用于根据uri获取数据
    				Cursor cursor = managedQuery(originalUri, proj, null, null,
    						null);
    
    				// 获得用户选择图片的索引值
    				int column_index = cursor
    						.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
    
    				// 将游标移至开头 ，防止引起队列越界
    				cursor.moveToFirst();
    
    				// 根据索引值获取图片路径
    				String path = cursor.getString(column_index);
    				imgPath.setText(path);
    			} catch (IOException e) {
    				Log.e("getImg", e.toString());
    
    			}
    		}
    	}
    	
    	/**
    	* 将彩色图转换为纯黑白二色
    	* 
    	* @param 位图
    	* @return 返回转换好的位图
    	*/
    	public static Bitmap convertToBlackWhite(Bitmap bmp) {
    		int width = bmp.getWidth(); // 获取位图的宽
    		int height = bmp.getHeight(); // 获取位图的高
    		int[] pixels = new int[width * height]; // 通过位图的大小创建像素点数组
    
    		bmp.getPixels(pixels, 0, width, 0, 0, width, height);
    		int alpha = 0xFF << 24;
    		for (int i = 0; i < height; i++) {
    			for (int j = 0; j < width; j++) {
    				int grey = pixels[width * i + j];
    
    				//分离三原色
    				int red = ((grey & 0x00FF0000) >> 16);
    				int green = ((grey & 0x0000FF00) >> 8);
    				int blue = (grey & 0x000000FF);
    				
    				//转化成灰度像素
    				grey = (int) (red * 0.3 + green * 0.59 + blue * 0.11);
    				grey = alpha | (grey << 16) | (grey << 8) | grey;
    				pixels[width * i + j] = grey;
    			}
    		}
    		//新建图片
    		Bitmap newBmp = Bitmap.createBitmap(width, height, Config.RGB_565);
    		//设置图片数据
    		newBmp.setPixels(pixels, 0, width, 0, 0, width, height);
    
    		Bitmap resizeBmp = ThumbnailUtils.extractThumbnail(newBmp, 380, 460);
    		return resizeBmp;
    	}
    
    }

示例代码地址： [http://download.csdn.net/detail/stop\_pig/8211315][http_download.csdn.net_detail_stop_pig_8211315]

[http_download.csdn.net_detail_stop_pig_8211315]: http://download.csdn.net/detail/stop_pig/8211315