1. Start with an image of your choice.

2. Create a Lasso, for example using the AutoMask function.

3. Your Lasso is not perfect, but you don't want to create a new one, because the rest of it is very fine. There are two ways to edit the effect:

4a. Press the SHIFT key and draw a free lasso a little greater around the defect

When you are ready, press the right mouse button.

4b. When it's more difficult, select Tool/Lasso/Convert Lasso to Layer. Now you have a vector layer and the tool bar changes to the vector toolbar.

Here you can select the Nippers and cut away the points.

You can even move the points with the Arrow or create new points with the Hammer.
When the path looks like you want, select Tool/Lasso/Convert Layer to Lasso.

4c. Another way to modify the lasso is to use the rubber tool. First you have to activate Work on Mask.

Then select the rubber tool

and work on the Mask (in our example green).

5. The result is a good placed lasso