DITHER_AMP_BITS   188 third_party/libwebp/dec/frame.c #define DITHER_AMP_CENTER (1 << DITHER_AMP_BITS)
DITHER_AMP_BITS   196 third_party/libwebp/dec/frame.c           VP8RandomBits2(rg, DITHER_AMP_BITS + 1, amp) - DITHER_AMP_CENTER;