private void normalizeContrast() {
		int[] histogram = new int[256];
		for (int i = 0; i < data.length; i++) {
			histogram[data[i]]++;
		}
		int[] remap = new int[256];
		int sum = 0;
		int j = 0;
		for (int i = 0; i < histogram.length; i++) {
			sum += histogram[i];
			int target = sum*255/picsize;
			for (int k = j+1; k <=target; k++) {
				remap[k] = i;
			}
			j = target;
		}
		
		for (int i = 0; i < data.length; i++) {
			data[i] = remap[data[i]];
		}
	}