android - How to make some part of bitmap transparent? -

i have bitmap http://i.hizliresim.com/gyr6jv.jpg on file system. need make black part of image transparent , obtain circular bitmap. transparent method used:

 public static bitmap maketransparent(bitmap bitmap, int replacethiscolor) {         if (bitmap != null) {             int picw = bitmap.getwidth();             int pich = bitmap.getheight();             int[] pix = new int[picw * pich];             bitmap.getpixels(pix, 0, picw, 0, 0, picw, pich);              (int y = 0; y < pich; y++) {                 // left right                 (int x = 0; x < picw; x++) {                     int index = y * picw + x;                     int r = (pix[index] >> 16) & 0xff;                     int g = (pix[index] >> 8) & 0xff;                     int b = pix[index] & 0xff;                      if (pix[index] == replacethiscolor) {                         pix[index] = color.transparent;                     } else {                         break;                     }                 }                  // right left                 (int x = picw - 1; x >= 0; x--) {                     int index = y * picw + x;                     int r = (pix[index] >> 16) & 0xff;                     int g = (pix[index] >> 8) & 0xff;                     int b = pix[index] & 0xff;                      if (pix[index] == replacethiscolor) {                         pix[index] = color.transparent;                     } else {                         break;                     }                 }             }              bitmap bm = bitmap.createbitmap(pix, picw, pich,                     bitmap.config.argb_8888);              return bm;         }         return null;     } 

thanks.

hey if want create circle image can use https://github.com/hdodenhof/circleimageview

edit: solution first draw transparent image form ressource draw image in disc (and disc)