Discover the GIMP Fuzzy Select Tool & How To Use It

The Fuzzy Select tool is used for making a selection of a portion of your image. In fact, with one click on your image, GIMP will auto-select an area… it’s magical! If you’re ready to discover how to use the Fuzzy Select tool… let’s do it…

What is the Fuzzy Select Tool {AKA the Magic Wand Tool}?

The Fuzzy Select tool is similar to the Magic Wand tool in Photoshop. It’s designed to select areas of your image based on color similarity. Although it’s magical, the (magic) fuzzy select tool is not perfect. To get the subject you want to be chosen, you’ll need to tweak the Tool Options.

Fuzzy Select Tool Options

There are five main parts to the fuzzy select tool options. This includes the Mode, behavior, Threshold, Select by, and Draw mask. Let’s go over each of them so you know how they affect what’s selected. First, select the Fuzzy Select tool (U) and then open the Tool Options; Windows > Dockable Dialogs > Tool Options.

Mode

From here, you’ll find four icons that will adjust what’s selected as follows…

Replace: Activated by default and creates the starting point. If you click on your image again, it will replace what's selected with the new color sample.
Add: As its name implies, this will add to your selection.
Subtract: This will remove from what's selected.
Intersect: Undefined by GIMP developers. I have no idea what this does.

Behaviors

These are part of the Modes. Although, I define them as “behaviors” since they alter your selection differently from a Mode.

Antialiasing: Creates a smooth edge around what's selected.
Feather Edges: When selected, a Radius slider is revealed, giving you control of the pixel depth for the edge's smoothness.
Select Transparent Areas: Allows completely transparent regions to be selected.
Sample Merged: This is useful when you have several layers in your image. The active layer is semi-transparent or set to a Layer Mode other than Normal.

If so, the colors sampled will be different vs. the colors in the composite image. If this option is not activated, the fuzzy select tool will only test colors from the selected layer and not multiple layers.
Diagonal Neighbors: This option increases the number of pixels considered for sampling the colors from 4 to 8.

Threshold

This option is the most widely used setting for pinpointing what’s selected. Increasing the Threshold will increase the number of colors sampled for your selection. In other words, the higher the Threshold, the more of your photo will be selected.

Select By

Narrow your color range by choosing a specific color channel: Composite (RGB), Red, Green, Blue, Alpha, HSV Hue, HSV Saturation, HSV Value, LCh Lightness, LCh Chroma, and LCh Hue.

Draw Mask

Use this when your selection is difficult to see. This could be due to the marching ants blending in with your image. If this occurs, activate this option, and a color mask will reveal the selected areas.

The mask will only be visible on your photo when you hold down your left mouse button. Also, make sure to do so in the same place where you clicked.

Tips For Using the Fuzzy Selection Tool

As with all the selection tools, the fuzzy select tool should be used in conjunction with other selection tools. Rarely will you get what you want to be selected from this tool from the start. Although tweaking the Tool Options will help, it’s still not going to be 100% perfect.

A Simple Photo

Photo by Jill Wellington

We have a solid black background with a vase and flowers set in the foreground for this photo. Making a selection of the background area can be made quickly with 1 click. Or you would think.

With the Threshold set to 5, I clicked on the background, and the results are pretty good. As you can see from the first image, the majority of the background was selected. However, there are spots where the background wasn’t included.

Also, there’s a reflection of the vase that has to be considered too. If the goal is to replace the background, then reflection might need to be included with the vase. That way, you can use the reflection for the new surface. That will depend on how dark the new surface is.

If you end up with a selection like this, you have two options;

One. Use another selection tool to select more of the background.

Two. Increase the Threshold to sample more colors from the background.

For this photo, my recommendation would be to increase the Threshold. Check out the selection for the second image, and you can see more of the background was captured. This was achieved by increasing the Threshold to 15. But, you can also see it’s still not perfect.

A Complex Photo

Our next photo is a bit more complicated. There’s a lot more detail in the surrounding area of my BFF; Echo. As you can see in the picture, I tried to select the background and failed. This is using the same Threshold level as before; 15.

Next, I tried 25 and 50 for the Threshold. The latter selected both the foreground and background. Twenty-five seems about right. But, as you can see, there’s still a lot to choose from.

This is when you’ll change the Mode to “Add” and click a new part of the background to, well, add it to your selection.

Truth be told, the Fuzzy Selection option wasn’t ideal for making a selection for this photo. A better tool would have been either the Foreground Select tool or Quick Mask mode.

What's Next?

The key to making selections in GIMP {quickly} is knowing how to use all the selection tools. Then, with practice, you’ll know which tool to use for a particular photo.

Check out some more free tutorials here and more advanced tutorials here.