Use Gimp to improve digital photos

Cloning
The Clone tool can remove unwanted objects from an image. You might have snapped an otherwise great photo marred only by an unwanted person or object in the frame, for example.

When retouching a photo, the Clone tool can be used to get rid of skin blemishes by cloning good skin, or in photo restoration you can get rid of a scratch by cloning an unscratched part of the image over it (and for more help on dealing with scratches and blemishes, see the guide below). The Clone tool acts like two brushes locked together – one copies part of an image in one area, the other paints an exact duplicate somewhere else.

To make use of the Clone tool in Gimp, first open an image, create a duplicate layer (from the Layer menu), then select the Clone tool from the Toolbox (the icon is a small rubber stamp). In the Clone tool options make sure that the Mode is Normal, Opacity is set at 100 per cent and Alignment is set at None.

Alignment defines the relationship between the source point and the brush position. By setting it to None, the same sample point is used each time you paint, even if you move to a different part of the image. (When Aligned is selected, the distance from the source point and the mouse pointer remains fixed, until a new source point is selected.)

If Sample Merged is checked in the Clone tool options, the tool clones from all layers. If unchecked, information is cloned from the selected layer only.

Choose an appropriate brush and use the scale slider to amend the size. The size needed will depend on the image and what part you intend removing from it, so you may need to try a few until you find a suitable one. Zoom in to the image if necessary.

Hold down the Control (Ctrl) key and click on the part of the image to be cloned. This defines the area of the image to be copied. Then, click (and hold) and move the pointer to ‘paint’ over the part to be removed. As you paint, a ringed cross will show you the area you are cloning.

Remove skin blemishes using Gimp

1. The Healing tool is often used to heal skin blemishes and wrinkles. Like the Clone tool, it uses sample points to copy pixels from one part of an image to another. Select the Healing tool (it looks like a sticking plaster) from the Toolbox, or press H.
2. Select an appropriate brush and size, then click to select the sample point. The Healing tool does not just copy the sample point, it uses the texture and tonal characteristics of the area around it and will blend this information into the area to be healed.
3. Paint over the area to be healed. Whereas the Clone tool is useful for removing details (such as an unwanted person) from an image, the Healing tool (because of its ability to blend to the area painted) is used for subtler changes.

Changing the source
To clone a different image element (or ‘source’), hold down the Control (Ctrl) key again and click on another area. Use several sample points when removing an object from a photo to give a more natural effect.

In some cases you may want to restrict the cloned area – perhaps it is very close to another object in the image that you do not want removed. In this case, use a selection. Choose the Free Select tool (it looks like a lasso) from the Toolbox and draw around the area that you want to fix.

The selection will then work as a barrier and will stop you removing anything outside the selection. When finished, get rid of the selection by choosing None from the Select menu.

To save the amended image, go to File, then Save As. Remember to give the image a different file name otherwise you will be saving over the original image. If you save it as a JPEG you will be prompted to export the image since .jpg files can’t retain multiple layers.

Once exported you can no longer re-open it and work with the individual layers that make up the image, because the layers will have been ‘flattened’ down to one. If you want to keep the layers you must save the image in a format that supports layers, such as Gimp’s own .xcf for or Photoshop (.psd).

Mastering the Gimp’s interface
While getting used to Gimp’s floating dialogue boxes and palettes you may make positional changes that you may want to undo. It’s an easy process to restore the original settings, so don’t ever be afraid to have a play around with Gimp.

Choose Edit then Preferences, then Window Management from the list down the left. Click Reset Saved Window Positions to Default Values, then OK.

A message will appear telling you the windows will be reset when Gimp is reopened. Click OK then close Gimp. When Gimp is reopened, the windows will have been restored to their original positions.

Tools and techniques
As we hope we have demonstrated, understanding how to use some of more advanced image-editing techniques really can pay off. With just a little bit of effort you can quickly make even the dullest photo the look bright and attractive.

It might be that you are content relying on automated image-enhancement options in your photo-editing tool. However, while it might take a little while to get used to all the advanced image-editing tools that are on offer, by taking things slowly and experimenting with each editing tool in turn you will soon build up a set of useful new skills.

If you don’t already have an image-editing application, it's worth considering Gimp as it is free to download and use and is every bit as powerful as paid-for applications – so there’s little to lose by giving it a go.

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