Modify Polygon Selection

The tool allows to modify the vertices of a polygon selection by clicking into the image. The nearest vertex will be moved to the coordinates of the click. In the options the x- or y- components can be fixed so that the vertex will only move vertically or horizontally. To try the tool create a polygon selection on an image.

Getting started

To install the tool, drag the link Modify_Polygon_Selection_Tool.ijm to the ImageJ launcher window. Save it under /plugins/tools in the ImageJ installation and restart ImageJ.

Select the "Modify_Polygon_Selection_Tool" from the >> button of the ImageJ launcher. This will add a button with a polygon selection icon to the current toolset.

the modify polygon selection tool


A right click on the button will open the options of the tool.

the options of the tool

  • fix x - when selected the x-coordinates of the vertices are fixed, they will only move vertically
  • fix y - when selected the y-coordinates of the vertices are fixed, they will only move horizontally
  • update roi-manager - when selected the active roi in the roi-manager is automatically updated after a click
  • help - pressing the help-button will open this help page

Using the tool

The aim of the tool is to allow moving the vertices of a selection along one coordinate axis without changing the coordinate along the other axis easily. You can use it for example if you need to manually correct the vertical position of vertices of a selection.

Select the tool and open an image with a polygon selection. Click to the new position of a vertex. The nearest vertex will move to this position or to the x- or y- component if the other component is fixed in the options. If you want to modify selections in the roi-manager you can select the "update" option. In this case a roi must be selected in the roi manager when you use the tool.