How to Flip a Selection in GIMP Without Flipping Pixels

In GIMP, flipping an active selection without altering the underlying image pixels is achieved by switching the transformation target within the tool's settings. By default, transformation tools affect the active layer's contents, but setting the tool mode to affect only the selection boundary allows you to mirror the marquee area while leaving the image completely intact.

Step 1: Create Your Selection

Ensure you have an active selection mask on your canvas using any of GIMP's selection tools, such as the Rectangle Select Tool (R), Ellipse Select Tool (E), or Free Select Tool (F).

Step 2: Activate the Flip Tool

Open the Flip Tool by selecting Tools > Transform Tools > Flip from the top menu, or by pressing the keyboard shortcut Shift + P.

Step 3: Set Transform Mode to Selection

  1. Locate the Tool Options dockable dialog (typically on the left side under the Toolbox).
  2. Find the Transform row at the very top of the options, which contains three icons: Layer, Selection, and Path.
  3. Click the second icon: Selection (represented by a red box with marching ants).

Step 4: Choose the Flip Direction

Under the Flip section in the Tool Options, select your desired direction:

  • Horizontal to mirror left-to-right.
  • Vertical to mirror top-to-bottom.

Alternatively, you can hold the Ctrl key while clicking on the canvas to toggle between horizontal and vertical modes on the fly.

Step 5: Apply the Flip

Click anywhere inside the image window. The selection outline will flip immediately across its center axis without disturbing or moving any of the pixels underneath.

Step 6: Reset the Transform Mode

Once the flip is complete, return to the Tool Options and set the Transform mode back to the first icon (Layer). This prevents unintended behavior the next time you use the Flip Tool to modify image content.