CSE 4227 · deck 09 · region growing

Region growing trainer: spread by eye

You don't need the queue. Circle the seed, keep circling any pixel that touches a circled one and is close enough, and stop when nothing new joins. The region you get is the same whatever order you go in. The page then turns your circles into the table you write in the exam.

The method

STEP 1Cross out the obvious outsiders: values far from everything near the seed (the 10s, 15s).
STEP 2Circle the seed.
STEP 3Spread: circle a pixel if it touches a circled one (4 or 8 neighbours) and |its value − that neighbour| ≤ T. One passing neighbour is enough.
STEP 4Stop when a full look over the grid circles nothing new. Write the table and the final grid.

Click a pixel: circle → cross → blank

seedcircled (in)crossed out
Click any pixel to see its circled neighbours and the differences.
Start with step 1: cross out the obvious outsiders, then spread from the seed.