Proofreading

Merge and Cut

AI reconstructions of neurons are impressive, but not perfect. Sometimes the AI misses a branch and leaves it as its own segment. Sometimes it runs two neurons into one. Two moves fix both, and EyeWire II teaches each one on a real cell that is yours while you practise.

Cheat sheet

Keep this tab open beside the viewer.

Merge tool	`M`
Cut tool	`C`
Place a point	`Ctrl` + click
Switch red and blue (cut)	`G`
Submit	`Enter`, or the Submit button on the bar at the bottom
Leave the tool	`Esc`
Fix a bad merge	Cut the pieces apart
Fix a bad cut	Merge them back

There is no undo key. Every edit is reversible with the opposite edit.

Merge: reconnect a lost branch

A merge joins two segments that belong to the same neuron.

A purple dendrite with a yellow branch the AI left as a separate segment — The yellow branch belongs to the purple cell, but the AI left it as its own segment. Open full size ↗

Select the segmentation layer (press 2, or right-click its chip at the top).
Press M. The merge bar appears at the bottom.
Ctrl + click the loose branch, then Ctrl + click the cell close to where the branch should join.
Press Submit merge or Enter. The server says "trying..." then "done", and the branch takes the cell's colour.

Merged the wrong thing? Cut it apart again. If a black box appears where the pieces meet, the new mesh is still being built: refresh the page.

Cut: separate two neurons

A cut splits one segment into two. Red points go on one side of the join, blue on the other, and the server finds the best place to separate them.

Before: a thin axon runs into a dendrite and the AI made them one segment — Before: a thin axon runs into this dendrite, and the AI made them one segment. Open full size ↗

After the cut: the axon, in yellow, is its own segment again — After the cut: the axon (yellow) is its own segment again. Open full size ↗

A segment with red points along the axon and blue points on the dendrite, ready to cut — A good set of points: red along the piece to remove, blue on the cell just past the join. Open full size ↗

Press C. The cut bar appears at the bottom, red group active.
Ctrl + click three or four red points on the piece that doesn't belong, working back from the join.
Press G to switch to blue, then Ctrl + click three or four blue points on the cell, just past the join.
Keep every point on this one segment. Points on a neighbour make the server refuse the cut ("supervoxels must belong to the same segment").
Press Submit cut or Enter. Wait for "splitting..." to finish.

Cut in the wrong place? Merge the pieces back and try again.

Try it on a real cell

In EyeWire II, open the book menu at the top right and pick Merge or Cut. Each tutorial hands you a sandbox cell that is yours alone while you work, walks you through the edit, and puts the cell back for the next person when you finish. If every cell is busy you join a short line and get a notification when one is yours.

Open EyeWire II ↗ Video tutorials