What is keyword to delete unnecessary element in binary image

Now, I try to extract only contour line from topographic map. I can convert image to binary data, and skeletonize the line. Then, I want to delete other unnecessary element like road line or signature. But I don't know what keyword is for that, like 'prune' or 'filter' and so on. How can I search what I want with some word?

Answer 1

[Nicolas Schmit]

Look here for a list of image filtering functions.

https://www.mathworks.com/help/images/image-enhancement-and-restoration.html

To remove small features, you can use imopen()