Abstract: Methods are disclosed for locating and focusing on a fiducial mark on a specimen slide. A plurality of pixels are identified as candidate pixels. A pixel is identified as a candidate pixel based on a number of empty pixels in an area defined by boundary lines extending from the pixel, and one or more dimensions, such as the perimeter, of the defined area. The candidate pixel enclosing the largest area is selected from the group or set of candidate pixels, and the coordinates of that pixel are considered to be the coordinates of the corner of the fiducial mark. The methods can be performed using different gray values that define dark or fiducial pixels and light or empty pixels. Differences between the results at different gray values can be used as focus scores for automatic focusing on the fiducial mark.

Abstract: Methods are disclosed for locating and focusing on a fiducial mark on a specimen slide. A plurality of pixels are identified as candidate pixels. A pixel is identified as a candidate pixel based on a number of empty pixels in an area defined by boundary lines extending from the pixel, and one or more dimensions, such as the perimeter, of the defined area. The candidate pixel enclosing the largest area is selected from the group or set of candidate pixels, and the coordinates of that pixel are considered to be the coordinates of the corner of the fiducial mark. The methods can be performed using different gray values that define dark or fiducial pixels and light or empty pixels. Differences between the results at different gray values can be used as focus scores for automatic focusing on the fiducial mark.