Android图片的二值化（黑白处理）
换了一家新公司，做的是自己的产品，也终于从外包转战到了产品行列。
入职后的第一天做的是一个图片处理的项目，主要是把彩色图片转换成黑白图片，同时读取图片的byte，里面只有-1,0，以方便在LED上边显示.
具体的效果如下图
文章图片
上边是原图，下边是二值化后的图片
上边的滑动条可以调节二值化的程度，同时上下两个图片都是可以拖动和任意缩放的
二值化的代码
/**
* 转为二值图像
*
* @param bmp
*原图bitmap
* @param w
*转换后的宽
* @param h
*转换后的高
* @return
*/
public static Bitmap convertToBMW(Bitmap bmp, int w, int h,int tmp) {
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
// 设定二值化的域值，默认值为100
//tmp = 180;
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
alpha = ((grey & 0xFF000000) >> 24);
int red = ((grey & 0x00FF0000) >> 16);
int green = ((grey & 0x0000FF00) >> 8);
int blue = (grey & 0x000000FF);
if (red > tmp) {
red = 255;
} else {
red = 0;
}
if (blue > tmp) {
blue = 255;
} else {
blue = 0;
}
if (green > tmp) {
green = 255;
} else {
green = 0;
}
pixels[width * i + j] = alpha << 24 | red << 16 | green << 8
| blue;
if (pixels[width * i + j] == -1) {
pixels[width * i + j] = -1;
} else {
pixels[width * i + j] = -16777216;
}
}
}
// 新建图片
Bitmap newBmp = Bitmap.createBitmap(width, height, Config.ARGB_8888);
// 设置图片数据
newBmp.setPixels(pixels, 0, width, 0, 0, width, height);
Bitmap resizeBmp = ThumbnailUtils.extractThumbnail(newBmp, w, h);
return resizeBmp;
}其中tmp就是二值化的阀值，可以根据拖动进行改变
private OnSeekBarChangeListener seekBarListener=new OnSeekBarChangeListener(){@Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
// TODO Auto-generated method stub
if(bitmap==null){}else{
tmp=(int)(progress*2.55);
Bitmap bitmapTmp=bitmap;
bitmapTmp = convertToBMW(bitmapTmp, dm.widthPixels, (int)(dm.heightPixels/2.3),tmp);
// 显得到bitmap图片
imgShow.setImageBitmap(bitmapTmp);
LinearLayout.LayoutParams mParams = new LinearLayout.LayoutParams(dm.widthPixels, (int)(dm.heightPixels/2.3));
mParams.topMargin=10;
imgShow.setLayoutParams(mParams);
}}@Override
public void onStartTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub}@Override
public void onStopTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub}};
其中拖动和缩放效果是copy的，但是已经忘记作者了，还请原作者原谅
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.FloatMath;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
public class MyImageView extends ImageView{
Matrix matrix = new Matrix();
Matrix savedMatrix = new Matrix();
/**位图对象*/
private Bitmap bitmap = null;
/** 屏幕的分辨率*/
private DisplayMetrics dm;
/** 最小缩放比例*/
float minScaleR = 1.0f;
/** 最大缩放比例*/
static final float MAX_SCALE = 15f;
/** 初始状态*/
static final int NONE = 0;
/** 拖动*/
static final int DRAG = 1;
/** 缩放*/
static final int ZOOM = 2;
/** 当前模式*/
int mode = NONE;
/** 存储float类型的x，y值，就是你点下的坐标的X和Y*/
PointF prev = new PointF();
PointF mid = new PointF();
float dist = 1f;
public MyImageView(Context context) {
super(context);
setupView();
}public MyImageView(Context context, AttributeSet attrs) {
super(context, attrs);
setupView();
}public void setupView(){
Context context = getContext();
//获取屏幕分辨率,需要根据分辨率来使用图片居中
dm = context.getResources().getDisplayMetrics();
//根据MyImageView来获取bitmap对象
BitmapDrawable bd = (BitmapDrawable)this.getDrawable();
if(bd != null){
bitmap = bd.getBitmap();
}//设置ScaleType为ScaleType.MATRIX，这一步很重要
this.setScaleType(ScaleType.MATRIX);
this.setImageBitmap(bitmap);
//bitmap为空就不调用center函数
if(bitmap != null){
center(true, true);
}
this.setImageMatrix(matrix);
this.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction() & MotionEvent.ACTION_MASK) {
// 主点按下
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
prev.set(event.getX(), event.getY());
mode = DRAG;
break;
// 副点按下
case MotionEvent.ACTION_POINTER_DOWN:
dist = spacing(event);
// 如果连续两点距离大于10，则判定为多点模式
if (spacing(event) > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
break;
case MotionEvent.ACTION_UP:{
break;
}
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
savedMatrix.set(matrix);
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
matrix.set(savedMatrix);
matrix.postTranslate(event.getX() - prev.x, event.getY()- prev.y);
} else if (mode == ZOOM) {
float newDist = spacing(event);
if (newDist > 10f) {
matrix.set(savedMatrix);
float tScale = newDist / dist;
matrix.postScale(tScale, tScale, mid.x, mid.y);
}
}
break;
}
MyImageView.this.setImageMatrix(matrix);
//CheckView();
return true;
}
});
}/**
* 横向、纵向居中
*/
protected void center(boolean horizontal, boolean vertical) {
Matrix m = new Matrix();
m.set(matrix);
RectF rect = new RectF(0, 0, bitmap.getWidth(), bitmap.getHeight());
m.mapRect(rect);
float height = rect.height();
float width = rect.width();
float deltaX = 0, deltaY = 0;
if (vertical) {
// 图片小于屏幕大小，则居中显示。大于屏幕，上方留空则往上移，下方留空则往下移
int screenHeight = dm.heightPixels;
if (height < screenHeight) {
deltaY = (screenHeight - height) / 2 - rect.top;
} else if (rect.top > 0) {
deltaY = -rect.top;
} else if (rect.bottom < screenHeight) {
deltaY = this.getHeight() - rect.bottom;
}
}if (horizontal) {
int screenWidth = dm.widthPixels;
if (width < screenWidth) {
deltaX = (screenWidth - width) / 2 - rect.left;
} else if (rect.left > 0) {
deltaX = -rect.left;
} else if (rect.right < screenWidth) {
deltaX = screenWidth - rect.right;
}
}
matrix.postTranslate(deltaX, deltaY);
}/**
* 限制最大最小缩放比例，自动居中
*/
private void CheckView() {
float p[] = new float[9];
matrix.getValues(p);
if (mode == ZOOM) {
if (p[0] < minScaleR) {
//Log.d("", "当前缩放级别:"+p[0]+",最小缩放级别:"+minScaleR);
matrix.setScale(minScaleR, minScaleR);
}
if (p[0] > MAX_SCALE) {
//Log.d("", "当前缩放级别:"+p[0]+",最大缩放级别:"+MAX_SCALE);
matrix.set(savedMatrix);
}
}
center(true, true);
}/**
* 两点的距离
*/
private float spacing(MotionEvent event) {
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return FloatMath.sqrt(x * x + y * y);
}/**
* 两点的中点
*/
private void midPoint(PointF point, MotionEvent event) {
float x = event.getX(0) + event.getX(1);
float y = event.getY(0) + event.getY(1);
point.set(x / 2, y / 2);
}
}这个用法很简单，直接在xml文件中调用就好了
【Android|Android图片的二值化（黑白处理）】最后给出源码好了
下载地址demo
明天将给出文字转图片并且二值化的分析
