region growing: Perform segmentation by region grow1ng.

[G, NR, SI, TI] = REGIONGROW(F, SR, T). Scan be an array (the same size as F) with a 1 at the coord1nates of every seed point and 0s elsewhere. S can also be a single seed value. Similarly, T can be an array (the same size as F) containing a threshold value for each pixel in F. T can also be a scalar, in wh1ch case it becomes a global threshold.