constructor(source) {
			super(source);
			this.luminances = GlobalHistogramBinarizer.EMPTY;
			this.buckets = new Int32Array(GlobalHistogramBinarizer.LUMINANCE_BUCKETS);
		}
This Binarizer implementation uses the old ZXing global histogram approach. It is suitable
for low-end mobile devices which don't have enough CPU or memory to use a local thresholding
algorithm. However, because it picks a global black point, it cannot handle difficult shadows
and gradients.

Faster mobile devices and all desktop applications should probably use HybridBinarizer instead.

@author dswitkin@google.com (Daniel Switkin)
@author Sean Owen