code: protected void setAllowedBounds(KltFeature feature) {
  		// compute the feature's width and temporary storage related to it
  		widthFeature = feature.radius * 2 + 1;
  		lengthFeature = widthFeature * widthFeature;
  
  		allowedLeft = feature.radius;
  		allowedTop = feature.radius;
  		allowedRight = image.width - feature.radius-1;
  		allowedBottom = image.height - feature.radius-1;
  
  		outsideLeft = -feature.radius;
  		outsideTop = -feature.radius;
  		outsideRight = image.width + feature.radius-1;
  		outsideBottom = image.height + feature.radius-1;
  	}
docs: Precompute image bounds that the feature is allowed inside of