在android中将图像转换为二进制图像

Question

iv = (ImageView) findViewById (R.id.uploadImage);

//convert the image view into bitmap
iv.buildDrawingCache();
bmap = iv.getDrawingCache();

int red;
int newPixel = 0;
int threshold =230;
int width = bmap.getWidth();
int hieght = bmap.getHeight();
int[] pix = new int[width * hieght];
int[] pix2 = new int[width * hieght];
int alpha = 0;

bmap.getPixels(pix, 0, width, 0, 0, width, hieght);

//convert the image into white and black
for (int i=0;i<width;i++) {  
  for (int j=0;j<hieght;j++) {
    int index = j * width + i;

    red = (pix[index] >> 16) & 0xff;
    alpha = (pix[index] >> 24) & 0xff;

    if (red<threshold) {
      newPixel = 0;
    } else {
      newPixel = 255;
    }
    newPixel = colorToRGB(alpha, newPixel, newPixel, newPixel);
    bmap.setPixel(i, j, newPixel);
    iv.setImageBitmap(bmap);     
  }
} 

//convert the black and white image view into bitmap                                    
bmap.getPixels(pix2, 0, bmap.getWidth(), 0, 0, bmap.getWidth(),bmap.getHeight());

StringBuilder builder = new StringBuilder();
for (int i :pix2) {
  builder.append("   " + i + "    ");
}
Toast.makeText(this, builder, Toast.LENGTH_LONG).show();

private static int colorToRGB (int alpha, int red, int green, int blue) {
  int newPixel = 0;
  newPixel += alpha;
  newPixel = newPixel << 8;
  newPixel += red; newPixel = newPixel << 8;
  newPixel += green; newPixel = newPixel << 8;
  newPixel += blue;
  return newPixel;
}

这是logcat

08-12 08:52:32.887:D/DalvikVM(774):GC_CONCURRENT释放71K,7%释放2765K/2964K,暂停23ms+15ms,总计94ms

08-12 08:52:33.497:D/gralloc_goldfish(774):检测到没有GPU仿真的仿真器。

08-12 08:52:40.698:D/DalvikVM(774):GC_CONCURRENT释放63K,6%释放3087K/3272K,暂停73ms+3ms,总计165ms

08-12 08:52:49.397:我/编舞（774）：跳过39帧！应用程序可能在其主线程上做了太多的工作。

08-12 08:52:54.568:D/DalvikVM(774):GC_FOR_ALLOC释放9K，5%释放3124K/3272K，暂停68ms，总计81ms

08-12 08:52:54.617:I/dalvikvm-heap（774）：将堆（frag大小写）增长到6.166MB，用于3145744字节分配

08-12 08:52:54.778:D/DalvikVM(774):GC_FOR_ALLOC释放40K，4%释放6155K/6348K，暂停156ms，总计156ms

08-12 08:52:55.008:D/DalvikVM(774):GC_CONCURRENT释放<1k，4%释放6155k/6348k，暂停80ms+38ms，总计231ms

08-12 08:52:55.898:我/编舞（774）：跳过412帧！应用程序可能在其主线程上做了太多的工作。

08-12 08:52:57.898:D/DalvikVM(774):GC_FOR_ALLOC释放38K，4%释放6119K/6348K，暂停28ms，总计30ms

08-12 08:52:57.929:I/dalvikvm-heap（774）：将堆（frag大小写）增长到9.091MB，用于3145744字节分配

08-12 08:52:58.058:D/DalvikVM(774):GC_CONCURRENT释放<1k，3%释放9191k/9424k，暂停82ms+6ms，总计125ms

08-12 08:52:58.058:D/DalvikVM(774):WAIT_FOR_CONCURRENT_GC阻塞40ms

08-12 08:52:58.089:I/dalvikvm-heap（774）：将堆（frag大小写）增长到12.090MB，用于3145744字节分配

08-12 08:52:58.218:D/DalvikVM(774):GC_FOR_ALLOC释放<1K，2%释放12263K/12500K，暂停125ms，总计126ms

08-12 08:52:58.288:D/DalvikVM(774):GC_CONCURRENT释放0K，2%释放12263K/12500K，暂停4ms+16ms，总计70ms

08-12 08:56:37.707:E/trace(886):打开跟踪文件时出错：没有这样的文件或目录（2）08-12 08:56:38.518:D/DalvikVM(886):GC_CONCURRENT释放41K,6%释放2805K/2968K,暂停13ms+3ms,总计77ms

08-12 08:56:38.518:D/DalvikVM(886):WAIT_FOR_CONCURRENT_GC阻塞10ms

08-12 08:56:38.727:D/gralloc_goldfish(886):检测到没有GPU仿真的仿真器。

08-12 08:56:55.107:D/DalvikVM(886):GC_FOR_ALLOC释放23K，5%释放3083K/3236K，暂停69ms，总计78ms

08-12 08:56:55.207:I/dalvikvm-heap（886）：将堆（frag大小写）增长到6.126MB，用于3145744字节分配

08-12 08:56:55.367:D/DalvikVM(886):GC_FOR_ALLOC释放1K，3%释放6153K/6312K，暂停156ms，总计156ms

08-12 08:56:55.607:D/DalvikVM(886):GC_CONCURRENT释放4K，3%释放6149K/6312K，暂停80ms+32ms，总计245ms

08-12 08:56:56.747:我/编舞（886）：跳过465帧！应用程序可能在其主线程上做了太多的工作。

08-12 08:58:03.287:D/DalvikVM(936):GC_CONCURRENT释放44K，6%释放2805K/2972K，暂停15ms+3ms，总计76ms

08-12 08:58:03.287:D/DalvikVM(936):WAIT_FOR_CONCURRENT_GC阻塞9ms

08-12 08:58:03.637:D/GRALLOC_GOLDFISH（936）：检测到没有GPU仿真的仿真器。

Answer 1

可能是因为您正在转换的位图是零字节：

//convert the image view into bitmap
            iv.buildDrawingCache();
            bmap = iv.getDrawingCache();

试试看：

BitmapDrawable bd = (BitmapDrawable) iv.getDrawable();
            bmap = bd.getBitmap();

希望这有帮助。