Android二值化

网上找了很多，没有一个能用的，本文的方法是自己在别人的基础上修改而来，纯Java算法，效率没有C++的高，追求效率的可以用Jni，具体参考：http://vaero.blog.51cto.com/4350852/822997
感谢网上分享的朋友们！
有图有真相：

接下来直接上代码：

public void binarization(Bitmap img) {width = img.getWidth();height = img.getHeight();int area = width * height;int gray[][] = new int[width][height];int average = 0;// 灰度平均值int graysum = 0;int graymean = 0;int grayfrontmean = 0;int graybackmean = 0;int pixelGray;int front = 0;int back = 0;int[] pix = new int[width * height];img.getPixels(pix, 0, width, 0, 0, width, height);for (int i = 1; i < width; i++) { // 不算边界行和列，为避免越界for (int j = 1; j < height; j++) {int x = j * width + i;int r = (pix[x] >> 16) & 0xff;int g = (pix[x] >> 8) & 0xff;int b = pix[x] & 0xff;pixelGray = (int) (0.3 * r + 0.59 * g + 0.11 * b);// 计算每个坐标点的灰度gray[i][j] = (pixelGray << 16) + (pixelGray << 8) + (pixelGray);graysum += pixelGray;}}graymean = (int) (graysum / area);// 整个图的灰度平均值average = graymean;Log.i(TAG,"Average:"+average);for (int i = 0; i < width; i++) // 计算整个图的二值化阈值{for (int j = 0; j < height; j++) {if (((gray[i][j]) & (0x0000ff)) < graymean) {graybackmean += ((gray[i][j]) & (0x0000ff));back++;} else {grayfrontmean += ((gray[i][j]) & (0x0000ff));front++;}}}int frontvalue = (int) (grayfrontmean / front);// 前景中心int backvalue = (int) (graybackmean / back);// 背景中心float G[] = new float[frontvalue - backvalue + 1];// 方差数组int s = 0;Log.i(TAG,"Front:"+front+"**Frontvalue:"+frontvalue+"**Backvalue:"+backvalue);for (int i1 = backvalue; i1 < frontvalue + 1; i1++)// 以前景中心和背景中心为区间采用大津法算法（OTSU算法）{back = 0;front = 0;grayfrontmean = 0;graybackmean = 0;for (int i = 0; i < width; i++) {for (int j = 0; j < height; j++) {if (((gray[i][j]) & (0x0000ff)) < (i1 + 1)) {graybackmean += ((gray[i][j]) & (0x0000ff));back++;} else {grayfrontmean += ((gray[i][j]) & (0x0000ff));front++;}}}grayfrontmean = (int) (grayfrontmean / front);graybackmean = (int) (graybackmean / back);G[s] = (((float) back / area) * (graybackmean - average)* (graybackmean - average) + ((float) front / area)* (grayfrontmean - average) * (grayfrontmean - average));s++;}float max = G[0];int index = 0;for (int i = 1; i < frontvalue - backvalue + 1; i++) {if (max < G[i]) {max = G[i];index = i;}}for (int i = 0; i < width; i++) {for (int j = 0; j < height; j++) {int in = j * width + i;if (((gray[i][j]) & (0x0000ff)) < (index + backvalue)) {pix[in] = Color.rgb(0, 0, 0);} else {pix[in] = Color.rgb(255, 255, 255);}}}Bitmap temp = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);temp.setPixels(pix, 0, width, 0, 0, width, height);image.setImageBitmap(temp);    }

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