Using GIMP's Rotate Tool

Take your images for a spin

GIMP logo

 Pixabay / CC0

GIMP's Rotate tool is quite easy to use, and once you've set the tool's options, clicking on the image opens the Rotate dialog. The slider adjusts the angle of the rotation; alternatively, you can click directly on the image and rotate it by dragging. The crosshairs that appear on the layer show the center point of the rotation, and you can drag this as desired.

The directions and screenshots here refer to GIMP version 2.10 on macOS, but other versions in Windows, Linux, and other operating systems are very similar.

GIMP rotate tool dialog

The Rotate Tool Options

GIMP's Rotate tool offers many options that are similar to those of other image editing apps such as Photoshop.

Ensure that the layer you want to rotate is selected in the layers palette.

GIMP layers palette

Transform

GIMP rotate layer option

By default, the Rotate tool operates upon the active layer; look to the right of Transform to see where to change this option to Selection or Path. Before using the Rotate tool, check the Layers or Paths palette to make sure the layer, selection, or path you want to rotate is the active one.

When rotating a selection, the selection will be obvious on the screen because of the selection's outline. If Transform is set to Layer, only the part of the active layer within the selection will be rotated.

Direction

The default direction setting is Normal (Forward); applying the Rotate tool turns the layer in the direction you've specified.

The other option is Corrective (Backward). At first glance, this seems to make little practical sense. However, this is an incredibly useful setting when you need to adjust horizontal or vertical lines in a photo, such as to straighten a horizon where the camera wasn't held straight.

GIMP View > Show Grid

To use the Corrective setting, select View > Show Grid (or, select Guides in the Rotate options and choose whatever option is most helpful, as shown later in this tutorial). Click on the layer with the Rotate tool, and rotate the grid until the horizontal lines of the grid are parallel with the horizon.

Straightening a horizon in GIMP

In the example above, the horizon will be aligned properly when the rotation is applied.

Interpolation

GIMP interpolation options

There are five Interpolation options for the GIMP Rotate tool. These affect the quality of the rotated image.

  • Cubic (the default) generally offers the highest quality and is usually the best option.
  • On computers with less processing power, the None option helps speed up the rotation if the other options are unacceptably slow; however, edges may appear jagged.
  • Linear offers a reasonable balance between speed and quality on less powerful machines.
  • NoHalo and LoHalo help remove halos, the artifacts that can appear around elements in images when they're altered. Experiment with these to find what works best for any particular image.

Clipping

GIMP clipping options for Rotate tool

This becomes relevant only if parts of the element being rotated will fall outside of the existing borders of the image.

  • When this option is set to Adjust, the parts of the layer outside of the image borders will not be visible but will continue to exist. So, if you move the layer, parts of the layer outside the image border can be moved back within the image and become visible.
  • When set to Clip, the layer is cropped to the image border; if you move the layer, there will be no areas outside of the image that will become visible.
  • Crop to result and Crop with aspect crop the layer after rotation, so that all corners are right angles, and the edges of the layer are horizontal or vertical.
  • Crop with aspect differs in that the resulting layer's proportions will match the layer before the rotation.

Guides

GIMP Rotate tool Guides options

The Guides option lets you select the type of guides you'd like displayed on the image to help you make your adjustments. The choices include:

  • No guides
  • Center lines
  • Rule of thirds
  • Rule of fifths
  • Golden sections
  • Diagonal lines
  • Number of lines
  • Line spacing

Choose whichever setting is most helpful for the adjustments you're performing.