Code for generating SIRDS

//======== Algorithm for drawing an autostereogram ========

#define DPI 75					//     Output device has 
						//    75 pixels per inch
#define E 2.5*DPI				//     Eye separation is 
						//    assumed to be 2.5"
#define mu (1/3.0)				//	  Depth of field

float separation(float Z)
{
  return (255-mu*Z)*E/(510-mu*Z);  		//     Stereo separation
} 						//    corresponding to Z
#define MAXX 256				//     screen dimensions
#define MAXY 256
int same[MAXX];			           	//  Points to a pixel to
						//     the right that is
					        //     constrained to be
                                   		//            this color
int pix[MAXX];					//     Colors for pixels
int separationLookup[256];		   	// lookup table for ste-
						//  reoseparation values
char lHidden[MAXX];				//   Z-puffer as seen by
char rHidden[MAXX];				//    left and right eye
void calcSeparationTable(void)	   		// pre-calculate stereo-
{						// disparity
int i,t;
	for(i=0;i<256;i++)
	{
		separationLookup[i]=separation(i);
	}
}
void DrawAutoStereogram(unsigned char zBuffer[][])
{		   				//      Objects depth is 
						// Z[x][y],from 0 to 255
  int x,y,i;					//    Coordinates of the
						//         current point
  unsigned s;					//  Stereo separation at
						//            this point
  int left, right;  			   	//  X-values correspond-
						// ing to left,right eye  
for(y=0;y=0)
	    lHidden[left]=zBuffer[y][i];
	}
	for (x=0; x < MAXX; x++)	  	//       process scanline
	{
	  left = x - separationLookup[zBuffer[x]]/2;			  
	  right = x +separationLookup[zBuffer[x]]- 
		separationLookup[zBuffer[x]]/2;
	  if (0 <= left && right < MAXX && 	// only if both imgs
		lHidden[left] == zBuffer[x] &&  //       are visible
		rHidden[right]== zBuffer[x])
	  {
		same[left] = right;		//         set constraint
	  }
	}
    for (x=MAXX-1 ; x>= 0 ; x--)  		//    set the pixels of a
    {						//              scan line
	  if (same[x]==x) pix[x] = random(2);   // Free choice 	  
	  else pix[x] = pix[same[x]];            // Constrained  
	  setPixel(x,y,pix[x]);		  	//   show pixel on screen
	}
  }
}