Android实现图像灰度化、线性灰度变化和二值化处理方法

1、图像灰度化：

public Bitmap bitmap2Gray(Bitmap bmSrc) {
  // 得到图片的长和宽
  int width = bmSrc.getWidth();
  int height = bmSrc.getHeight();
  // 创建目标灰度图像
  Bitmap bmpGray = null;
  bmpGray = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
  // 创建画布
  Canvas c = new Canvas(bmpGray);
  Paint paint = new Paint();
  ColorMatrix cm = new ColorMatrix();
  cm.setSaturation(0);
  ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
  paint.setColorFilter(f);
  c.drawBitmap(bmSrc, 0, 0, paint);
  return bmpGray;
}

2、对图像进行线性灰度变化

public Bitmap lineGrey(Bitmap image) {
  //得到图像的宽度和长度
  int width = image.getWidth();
  int height = image.getHeight();
  //创建线性拉升灰度图像
  Bitmap linegray = null;
  linegray = image.copy(Config.ARGB_8888, true);
  //依次循环对图像的像素进行处理
  for (int i = 0; i < width; i++) {
    for (int j = 0; j < height; j++) {
      //得到每点的像素值
      int col = image.getPixel(i, j);
      int alpha = col & 0xFF000000;
      int red = (col & 0x00FF0000) >> 16;
      int green = (col & 0x0000FF00) >> 8;
      int blue = (col & 0x000000FF);
      // 增加了图像的亮度
      red = (int) (1.1 * red + 30);
      green = (int) (1.1 * green + 30);
      blue = (int) (1.1 * blue + 30);
      //对图像像素越界进行处理
      if (red >= 255)
      {
        red = 255;
      } 

      if (green >= 255) {
        green = 255;
      } 

      if (blue >= 255) {
        blue = 255;
      }
      // 新的ARGB
      int newColor = alpha | (red << 16) | (green << 8) | blue;
      //设置新图像的RGB值
      linegray.setPixel(i, j, newColor);
    }
  }
  return linegray;
}

3、对图像进行二值化

public Bitmap gray2Binary(Bitmap graymap) {
  //得到图形的宽度和长度
  int width = graymap.getWidth();
  int height = graymap.getHeight();
  //创建二值化图像
  Bitmap binarymap = null;
  binarymap = graymap.copy(Config.ARGB_8888, true);
  //依次循环，对图像的像素进行处理
  for (int i = 0; i < width; i++) {
    for (int j = 0; j < height; j++) {
      //得到当前像素的值
      int col = binarymap.getPixel(i, j);
      //得到alpha通道的值
      int alpha = col & 0xFF000000;
      //得到图像的像素RGB的值
      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);
      //对图像进行二值化处理
      if (gray <= 95) {
        gray = 0;
      } else {
        gray = 255;
      }
      // 新的ARGB
      int newColor = alpha | (gray << 16) | (gray << 8) | gray;
      //设置新图像的当前像素值
      binarymap.setPixel(i, j, newColor);
    }
  }
  return binarymap;
}

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