[구현(c)/no ref.]Hysteresis Thresholding

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#define LOW_THRESHOLD_INTENSITY			63
#define HIGH_THRESHOLD_INTENSITY		127

void RunHysteresisThresholding(unsigned char* input, unsigned char* output, int imageWidth, int imageHeight)
{

	int low = LOW_THRESHOLD_INTENSITY;
	int high = HIGH_THRESHOLD_INTENSITY;

	register int i, j;

	for(i=0; i<imageHeight; i++) 
	{
		for(j=0; j<imageWidth; j++) 
		{
			if(input[i*imageWidth+j] > high) 
			{
				output[i*imageWidth+j] = 255;
			} 
			
			else 
			{
				output[i*imageWidth+j] = 0;
			}
		}
	}

	int grown;

	do {
		grown = 0;
		for(i=0; i<imageHeight; i++) 
		{
			for(j=0; j<imageWidth; j++) 
			{
				if(input[i*imageWidth+j] > low && CheckNeighbor(output, imageWidth, imageHeight, i, j)) 
				{
					output[i*imageWidth+j] = 255;
					grown++;
				}
			}
		}
	} while(grown>0);

}

int CheckNeighbor(unsigned char* target, int imageWidth, int imageHeight, int i, int j) 
{
	if(target[i*imageWidth+j]>0)
	{
		return 0;
	}

	if(i>0 && target[(i-1)*imageWidth+j]>0)
	{
		return 1;
	}

	if(i>0 && j>0 && target[(i-1)*imageWidth+(j-1)]>0)
	{
		return 1;
	}

	if(j<imageWidth-1 && target[i*imageWidth+(j+1)]>0)
	{
		return 1;
	}

	if(i<imageHeight-1 && j<imageWidth-1 && target[(i+1)*imageWidth+(j+1)]>0)
	{
		return 1;
	}

	return 0;
}