How to Change the Colour of an Object in GIMP

Open Your Image in GIMP

Start by opening GIMP and loading the photograph you want to edit.

For this example, we’re using a photograph containing several pieces of fruit. This makes it easy to demonstrate how individual objects can be selected and given completely different colours without changing the rest of the photograph.

You can use the same technique with your own image. The object doesn’t need to be fruit – it could be clothing, a product, part of a building or another clearly defined area within a photograph.

Duplicate the Image Layer

Before making any changes, it’s a good idea to duplicate the original image layer.

In the Layers panel, right-click your image layer and select:

Duplicate Layer

You’ll now have two copies of the photograph.

Keep the original layer underneath as a backup and make your changes to the duplicated layer above it.

Working this way means you can easily compare your edited photograph with the original or return to the unedited version if necessary.

Select the Foreground Select Tool

Choose the Foreground Select Tool from the GIMP toolbox.

This tool is particularly useful when you need to isolate an object from the surrounding photograph.

Zoom into the object you want to recolour so you can see its edges more clearly.

You can then begin clicking around the outside of the object to create a rough outline.

You don’t need to trace every edge with pixel-perfect accuracy at this stage. The objective is to create a boundary around the object and separate it from the rest of the photograph.

Continue around the object until you reach your starting point, then join the selection.

Press Enter to continue.

Mark the Object You Want to Select

GIMP will now ask you to identify the foreground area inside your outline.

Use the brush to paint over the object you want to select.

You don’t need to paint precisely around every edge. Concentrate on painting inside the object while avoiding areas outside it.

Adjust the brush size depending on the object you’re working with. A larger brush is useful for filling the centre, while a smaller brush gives you more control around narrow or detailed areas.

Once you’ve marked the object, allow GIMP to calculate the foreground selection.

You should then see a more accurate selection around its edges.

Take Your Time Around the Edges

The quality of your final colour change depends heavily on the quality of your selection.

If your selection extends onto another object or misses part of the object you’re editing, the colour adjustment may become visible in places where it shouldn’t.

Zoom in when necessary and spend a little more time around complicated edges.

If you make a mistake while marking the foreground, use Ctrl + Z to undo your last action.

It can also help to work in smaller strokes rather than trying to paint the entire foreground in one continuous movement. If you make a mistake, you’ll then only need to undo the most recent stroke.

Change the Object Colour Using Hue-Saturation

Once you’re happy with the selection, you can change its colour.

Go to:

Colours > Hue-Saturation

Adjust the Hue setting and watch how the selected object’s colour changes.

Move the control until you find a colour that works with your image.

Because you’ve already created a selection, the adjustment should affect the selected object rather than changing the colours across the entire photograph.

When you’re happy with the result, apply the change.

Then go to:

Select > None

This removes the active selection so you can continue working on another part of the image.

Change the Colour of Another Object

You can repeat exactly the same process to recolour additional objects.

Select the Foreground Select Tool again and draw a rough outline around the next object.

Press Enter and paint inside the area you want GIMP to recognise as the foreground.

Once GIMP has created the selection, open:

Colours > Hue-Saturation

This time, choose a different hue.

For example, if you changed the first object to purple, you could make the second object blue. You can continue this process to create as many colour variations as you need.

Selecting Objects That Overlap

Some objects are more difficult to select because another object overlaps them.

The same Foreground Select technique can still be used, but you’ll need to take more care when creating the initial outline.

Follow the visible edge of the object and then trace around the boundary of anything sitting in front of it.

After creating the rough outline, mark the foreground area as before.

This is another situation where zooming in can make the selection considerably easier.

Once you’ve created a clean selection, use Hue-Saturation to change the colour and then choose Select > None when you’ve finished.

Fix Selection Mistakes Before Changing the Colour

If you notice that part of your colour adjustment has affected the wrong area, the selection probably needs refining.

It’s worth fixing these problems before continuing with the rest of the image.

Small errors around an edge may not be particularly noticeable when you’re zoomed in and concentrating on the editing process, but they can become much more obvious when you view the completed image at its normal size.

A few extra moments spent improving the selection will normally produce a cleaner result.

Change a Background Colour with the Fuzzy Select Tool

You don’t always need to use the Foreground Select Tool.

If the area you want to change contains a relatively consistent colour, the Fuzzy Select Tool can provide a much quicker solution.

Select the Fuzzy Select Tool and click on the background area you want to change.

The Threshold setting controls how similar neighbouring colours need to be before they’re included in the selection.

A lower threshold creates a more restrictive selection, while a higher threshold allows a wider range of similar colours to be included.

Adjust the threshold until the area you want to edit is selected without including too much of the surrounding photograph.

Once you’re happy with the selection, go to:

Colours > Hue-Saturation

Adjust the hue until you find the background colour you want.

When you’ve finished, choose:

Select > None

Foreground Select vs Fuzzy Select

The tool you choose will depend on the image you’re editing.

The Foreground Select Tool is useful when you’re trying to isolate a recognisable object from the rest of a photograph. It gives you more control when the object contains different colours, highlights and shadows.

The Fuzzy Select Tool can be quicker when you’re working with a larger area of similar colour, such as a simple background.

Neither tool will be perfect for every photograph. The complexity of the image, contrast between objects and amount of detail around the edges will all affect the quality of the selection.

Keep the Original Shading and Detail

One of the advantages of changing colour with Hue-Saturation is that you’re adjusting the existing colours rather than simply painting a solid colour over the object.

This helps retain details such as:

• highlights;
• shadows;
• texture;
• reflections; and
• natural variations in brightness.

As a result, the recoloured object can still retain much of the depth and detail found in the original photograph.

This can produce a more natural-looking result than simply painting a flat colour over the top.

Save Your Editable GIMP Project

Before exporting the finished image, save an editable version of your project.

Keeping the GIMP project means you can return later if you want to make further adjustments.

For example, you might decide to change one of the colours again, improve a selection or create several alternative versions of the same photograph.

Saving your working file before exporting gives you much more flexibility.

Export the Finished Image

When you’re happy with the colour changes, go to:

File > Export As

Choose your filename and the image format you want to use.

For a standard photograph without transparency, JPEG will normally be suitable.

After exporting, open the original and edited images and compare them side by side.

Pay particular attention to the edges of the objects you’ve recoloured. If you notice small patches of the original colour or areas where the new colour has spread beyond the object, return to your GIMP project and refine the selection.

What Can You Recolour in GIMP?

The same technique can be applied to many different types of images.

For example, you could change the colour of:

• clothing;
• products;
• furniture;
• vehicles;
• buildings;
• flowers;
• backgrounds; or
• individual elements within artwork.

The main requirement is being able to create a suitable selection around the area you want to edit.

Objects with clear boundaries are generally easier to work with, while detailed edges, similar foreground and background colours, or transparent objects can require more careful selection work.

A Simple Way to Change Object Colours in GIMP

Changing the colour of an object in GIMP becomes much easier once you understand how to create a good selection.

The basic process is straightforward:

1. Open your image in GIMP.
2. Duplicate the original image layer.
3. Choose the Foreground Select Tool.
4. Draw around the object you want to recolour.
5. Mark the foreground area.
6. Create the final selection.
7. Open Colours > Hue-Saturation.
8. Adjust the hue to create the new colour.
9. Remove the selection.
10. Repeat the process for any additional objects.
11. Save your editable GIMP project.
12. Export the finished image.

For areas with a consistent background colour, the Fuzzy Select Tool can make the process even quicker.

Once you’ve practised the selection process a few times, you can use the same approach to experiment with different colours across a wide range of photographs without changing the entire image.