This GIMP (GNU) tutorial demonstrates how to extract an object from its background using GIMP’s Foreground Select Tool. To work along, you are welcome to download the Start Image I am working with Here. Unzip the file and open the Start Images onto GIMP’s workspace.
Foreground Select Tool Notes
The creation of a Selection with this Tool works in a couple of steps: roughly select the Foreground you want to extract. When you select this Tool, the mouse pointer goes with the Lasso icon. This Tool works like the Fuzzy Select Tool. Select as little as possible from the background. As soon as you release the mouse button, the non selected part of the image is covered with a dark blue mask. (If the selection is not closed, its ends will be linked automatically together by a straight line).
You can quickly Undo a step at any time by pressing Ctrl then Z. Alternatively, click a previous Undo History snapshot - Windows then Dockable Dialogues then click Undo History. In addition, to Zoom in (or Zoom out) of your image; from the top menu, choose View then select a Zoom Tool from the subsequent drop-down list.
Launch GIMP & Organise Its Workspace & Palettes
Ensure the Layers and the Undo History Palettes are visible, and then drag them into position over your workspace - (Windows then Dockable Dialogues - then click Layers and Undo History).
Select By Colour Tool Notes
This Tool lets you extract the Foreground from the Active Layer or from a
Selection. It is based on the SIOX method (Simple Interactive Object Extraction).
Open your choice of Start Image onto GIMP’s workspace - File then Open - Ctrl then O.
Then from the left-side Toolbox, activate the Foreground Select Tool.
And enter the following settings into the Options Box.
Preview Colour Note
If your Start Image’s background is a dark blue colour, then (to be able to see the subsequent Overlay), you’ll need to change the Preview colour from Blue, to a colour that will be noticeable over your Start Image’s background colour.
Now, left-click and roughly draw a Lasso Line around the object’s background - as illustrated below.
Because you’ll be retaining the Lily, and extracting its background, don’t touch the Lily with the Lasso Line. You can cancel the Lasso Line by tapping your Keyboard’s Escape Key.
After you have applied the Lasso Line, pass it over the exact area where you
began, and release the left-mouse button. The majority of the Lily’s background will now be covered with a Blue Overlay - as illustrated below.
Congratulations, you are ready for the next step.
Now, (still using the Foreground Select Tool), left-click and paint inside the object you want to retain. In this instance, I have roughly painted over the Lily.
Then release the mouse button.
The Blue Overlay should now completely cover the Lily’s background - as illustrated below.
Finish by tapping your Enter/Return Key. Tapping your Enter/Return Key isolates the object (the Lily), with the following Selection Marquee.
Selection Marquee Tip
If necessary, you can Shrink, Grow or Feather the Selection Marquee so it hugs the Lily tightly (top menu, then Select).
From the Layers Palette, right-click over the Background Layer and select Add Alpha Channel from the subsequent drop-down list.
Then from the top menu, choose Select and then choose Invert - Ctrl then I.
It’s time to remove the Lily’s Background. Therefore, from the top menu, choose Edit and then choose Clear - or tap your Delete Key. After clicking Clear, the Background area will be removed.
Removing the background reveals the following Chessboard Transparency. The Chessboard Background is GIMP’s way of informing you that the background is Transparent.
Congratulations, you have successfully removed your object’s background using the Foreground Select Tool.
From the top menu, choose Select and then choose None.
Lasso And Eraser Tool Tip
If necessary, you remove background pixels that the Foreground Select Tool has missed, using either the Eraser Tool or the Free Select Tool.
Drop Shadow Tip
My Tutorial Here demonstrates how to apply a Drop Shadow - Filters then Light and Shadow then Drop Shadow.
Transparent GIF Tip
Link Here to learn how to save your Transparent Image as a Transparent GIF.
Fill Layer Tip
My Tutorial Here demonstrates how to create a Fill Layer and Fill it with either a Solid Colour, Pattern or a Gradient.
Blur Tool Tip
Ragged edges can be smoothed utilising the Blur Tool. (Set a Blur Rate of around 15).
To finish, from the top men, choose Image and then choose Flatten Image.
Congratulations, your object extraction is complete, and is ready to optimise and save.
Now you are more familiar with this technique, you can have lots of fun removing backgrounds from your favourite objects.
Wendi E. M. Scarth. Top of Page.