Figure 3.

Illustration of the nuclear neighborhood search algorithm. (A) A schematic of the contour expansion approach in which the nuclear neighborhood is scanned starting at the surface of the nucleus (black ring) and extending to layers (red, green, and blue layers) beyond the surface layer of pixels. Each layer is one pixel wide in an eight-neighborhood sense. (B) The contour expansion approach is illustrated at the pixel level. Pixels labeled as 1, 2, and 3 correspond to different layers starting from the surface of the nucleus. (C) A nuclear neighborhood filter is then constructed from the contour pixels shown in (B). The filter image of the nucleus has the same dimension as the original fluorescent image. (D) The connexin channel in the original fluorescent image is illustrated here. Each pixel in the connexin channel image is then multiplied with the corresponding pixel in the filter image to extract the pixels in the nuclear neighborhood that are occupied by connexins (E).