If you expand a square or rectangular selection, the corners become rounded. In the following image, the selection on the left was expanded 30 pixels using Selections...Modify...Expand to produce the selection on the right:
selection expanded
If you want to keep the corners of a rectangular selection square when you expand the selection, use either of the following methods:
Use Edit Selection to expand the selection:
After creating the selection, choose Selections...Edit Selection.
Choose Image...Resize ('All layers' UNchecked) or use the Pick tool (K) or the Raster Deform tool (which is still available using its old shortcut key, D) to increase the size of the selection.
Choose Selections...Edit Selection to return to the selection marquee.
Use Selections...Modify...Expand to expand the selection, and then click on the 'Current selection' button in the 'Create selection from' section of the Selection tool Tool Options palette:
current selection button
Note: This second method will only work if the selection is a rectangle with sides parallel to the images edges.
In the following image, the selection on the left was expanded 10 pixels using Selections...Modify...Expand. The selection in the center was expanded the same number of pixels using the first method above. The selection on the right was created by applying the second method above directly to the image on the left. All selections were filled with color for visibility. Note the difference in the corners of the expanded, filled selections - either way gives you crisp, square corners:
expanded selections
selection expanded
If you want to keep the corners of a rectangular selection square when you expand the selection, use either of the following methods:
Use Edit Selection to expand the selection:
After creating the selection, choose Selections...Edit Selection.
Choose Image...Resize ('All layers' UNchecked) or use the Pick tool (K) or the Raster Deform tool (which is still available using its old shortcut key, D) to increase the size of the selection.
Choose Selections...Edit Selection to return to the selection marquee.
Use Selections...Modify...Expand to expand the selection, and then click on the 'Current selection' button in the 'Create selection from' section of the Selection tool Tool Options palette:
current selection button
Note: This second method will only work if the selection is a rectangle with sides parallel to the images edges.
In the following image, the selection on the left was expanded 10 pixels using Selections...Modify...Expand. The selection in the center was expanded the same number of pixels using the first method above. The selection on the right was created by applying the second method above directly to the image on the left. All selections were filled with color for visibility. Note the difference in the corners of the expanded, filled selections - either way gives you crisp, square corners:
expanded selections
