I am new to Adobe illustrator. We can change to Outline Stroke from Path. Is it possible reverse. How to change from Outline Stroke to path
Nothing except UNDO or File > Revert to saved can do it perfectly. If they cannot be used you can try an approximation. It's not exact but it can be usable. A common method to try is offset path:
The grey shape is the outlined stroke. The stroke width was 8 mm to get easy to see image for this demo. The red curve is the original path with a narrow stroke, for demo only. We try to recreate it.
Remove the fill, insert a narrow stroke
Decide which side would be less wrong if it's shifted. Here the outer edge is decided to be better. The other side is moved further with the direct selection tool (=move nodes). The ends are kept to have their original orientations, they are only longer
Object > Path > Offset Path > -4mm is applied, the orange curve is the result.
The orange curve is splitted with scissors and the unnecessary part is deleted
The orange curve is stretched to full length with the direct selection tool. Before stretching it can be useful it can be useful to insert with the anchor insertion tool a couple of guard nodes near the end nodes to prevent curvature changes. it happens easily when nodes are moved.
Here's the result placed onto the test curve.It's not perfect, but it can be usable:
As you see the ends are not perfectly sretched. An easy way to improve it is to insert some markers for the estimated stroke ends. A duplicate of curve 2 is excellent. You get a mid-end node by applying Object > Path > Add Anchor points.
Other popular methods for the same:
Split the outline to 2 curves at the ends. Make a 1 step blend and expand it. It works if both halves have approximately the same distribution of nodes. Insert them with the anchor insertion tool to get the halves balanced.
Split the outline to 2 curves at the ends. Give to one of them haw width stroke. Outline it and split the result. One of the halves should be approximately the wanted path.
Both methods can need manual fixes at the ends. 1 is useless if the node distributions are different.
If the outlined stroke was a closed curve, there's no need to worry stroke ends. Only release the compound path and decide do you want to offset the hole shape outwards or the outer shape inwards.