One way or another, get the union of the two selected areas from the channels. Simply using NOT before the ST_Intersects does the trick: This gets all addresses that are not within neighborhood #62: select a. with the existing rectangular selection. Subtract mode will remove the new selection area from any existing selection regions. March 10, 2021. This is because you have a selection (the square on the top right) which selects pixels that are all outside the layer that you are trying to act on. To learn more, see our tips on writing great answers. You can change the aspect of the selection after it has been drawed, by moving the small . GNU Image Manipulation Program is a free cross-platform image editor made by The GIMP Team. For a full understanding of all Gimp tricks with selections, please read Selection Control. Script-Fu is the current default script language and it is based on Scheme. BoxAdcontent.document.write("