convert an image to binary image in android

Question

I'm trying to build simple android project to convert image to binary format , but when I check pixels value ,i get zeros only. I don't know where is the problem. Any one can help me please. This is my code

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;
}

this is logcat

08-12 08:52:32.887: D/dalvikvm(774): GC_CONCURRENT freed 71K, 7% free 2765K/2964K, paused 23ms+15ms, total 94ms

08-12 08:52:33.497: D/gralloc_goldfish(774): Emulator without GPU emulation detected.

08-12 08:52:40.698: D/dalvikvm(774): GC_CONCURRENT freed 63K, 6% free 3087K/3272K, paused 73ms+3ms, total 165ms

08-12 08:52:49.397: I/Choreographer(774): Skipped 39 frames! The application may be doing too much work on its main thread.

08-12 08:52:54.568: D/dalvikvm(774): GC_FOR_ALLOC freed 9K, 5% free 3124K/3272K, paused 68ms, total 81ms

08-12 08:52:54.617: I/dalvikvm-heap(774): Grow heap (frag case) to 6.166MB for 3145744-byte allocation

08-12 08:52:54.778: D/dalvikvm(774): GC_FOR_ALLOC freed 40K, 4% free 6155K/6348K, paused 156ms, total 156ms

08-12 08:52:55.008: D/dalvikvm(774): GC_CONCURRENT freed <1K, 4% free 6155K/6348K, paused 80ms+38ms, total 231ms

08-12 08:52:55.898: I/Choreographer(774): Skipped 412 frames! The application may be doing too much work on its main thread.

08-12 08:52:57.898: D/dalvikvm(774): GC_FOR_ALLOC freed 38K, 4% free 6119K/6348K, paused 28ms, total 30ms

08-12 08:52:57.929: I/dalvikvm-heap(774): Grow heap (frag case) to 9.091MB for 3145744-byte allocation

08-12 08:52:58.058: D/dalvikvm(774): GC_CONCURRENT freed <1K, 3% free 9191K/9424K, paused 82ms+6ms, total 125ms

08-12 08:52:58.058: D/dalvikvm(774): WAIT_FOR_CONCURRENT_GC blocked 40ms

08-12 08:52:58.089: I/dalvikvm-heap(774): Grow heap (frag case) to 12.090MB for 3145744-byte allocation

08-12 08:52:58.218: D/dalvikvm(774): GC_FOR_ALLOC freed <1K, 2% free 12263K/12500K, paused 125ms, total 126ms

08-12 08:52:58.288: D/dalvikvm(774): GC_CONCURRENT freed 0K, 2% free 12263K/12500K, paused 4ms+16ms, total 70ms

08-12 08:56:37.707: E/Trace(886): error opening trace file: No such file or directory (2) 08-12 08:56:38.518: D/dalvikvm(886): GC_CONCURRENT freed 41K, 6% free 2805K/2968K, paused 13ms+3ms, total 77ms

08-12 08:56:38.518: D/dalvikvm(886): WAIT_FOR_CONCURRENT_GC blocked 10ms

08-12 08:56:38.727: D/gralloc_goldfish(886): Emulator without GPU emulation detected.

08-12 08:56:55.107: D/dalvikvm(886): GC_FOR_ALLOC freed 23K, 5% free 3083K/3236K, paused 69ms, total 78ms

08-12 08:56:55.207: I/dalvikvm-heap(886): Grow heap (frag case) to 6.126MB for 3145744-byte allocation

08-12 08:56:55.367: D/dalvikvm(886): GC_FOR_ALLOC freed 1K, 3% free 6153K/6312K, paused 156ms, total 156ms

08-12 08:56:55.607: D/dalvikvm(886): GC_CONCURRENT freed 4K, 3% free 6149K/6312K, paused 80ms+32ms, total 245ms

08-12 08:56:56.747: I/Choreographer(886): Skipped 465 frames! The application may be doing too much work on its main thread.

08-12 08:58:03.287: D/dalvikvm(936): GC_CONCURRENT freed 44K, 6% free 2805K/2972K, paused 15ms+3ms, total 76ms

08-12 08:58:03.287: D/dalvikvm(936): WAIT_FOR_CONCURRENT_GC blocked 9ms

08-12 08:58:03.637: D/gralloc_goldfish(936): Emulator without GPU emulation detected.

hope this will help you stackoverflow.com/questions/13770181/… — nayab

user2652394 user2652394 · Accepted Answer · 2013-08-12T08:44:45

Maybe because the bitmap you are converting is zero-byte:

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

Try this:

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

Hope this helps.

convert an image to binary image in android

1 Answers