This GIMP (GNU) tutorial demonstrates how to extract an object’s background using the Paths Tool. To work along, you are welcome to download the Start Image I am working with Here. Unzip the file and open the image onto GIMP’s workspace.
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
Open your choice of Start Image onto GIMP’s workspace - File then Open - Ctrl then O.
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).
2/ Add An Alpha Channel
Now, from the Layers Palette: right-click over the Background Layer, and from the subsequent drop-down list, click Add Alpha Channel.
Then from the left-side Toolbox, activate the Paths Tool.
And ensure the following (default) settings are active in the Paths Tool’s Options Box.
You will find the crystal’s extraction much easier if you enlarge your image by Zooming into it.
I zoomed in twice.
You are looking to isolate just the crystal’s edge with a Path.
Therefore, left-click once anywhere along the crystal’s edge. This applies your first anchor point, as illustrated below.
At this point, it’s not crucial that your Path is perfectly positioned. This is because, before closing the Path, you can go back at any time and edit it.
After applying your first anchor point, left-click and apply a second anchor point a little further along the crystal’s edge - as illustrated below.
Beginners, you will find this much easier if you apply your anchor points close together; - perhaps in two inch (5.08 cm) intervals.
Now, continue to left-click and apply multiple anchor points around the crystal’s edges.
Undo An Anchor Point
You can quickly undo an anchor point by pressing Ctrl then Z. To cancel the Path, click any other Tool, perhaps the Move Tool. However, remember to reactivate the Paths Tool when you are ready ready to apply your Path.
After you have clicked a Path completely around the crystal, place the final anchor point just short of the first, as illustrated below. It’s important at this stage not to close the Path.
Congratulations, you have applied a Path around the crystal’s edges, and you are ready for the next step.
4/ Reposition The Path
Left-click over your choice of anchor point, and gently tug it - as illustrated
below-left. This moves the Path as if it where soft wire. Now, with your mouse, gently reposition the Path so that it closely hugs the edge of the crystal (in a straight line) - as illustrated below-right.
Then continue to reposition the Path so it closely hugs the crystal’s edges, by (one at a time) gently tugging the relevant anchor point. After you have completed this, you are ready for the next step.
5/ Close The Path
To close the Path, left-click over the very first anchor point that you applied back in Chapter 3 - as illustrated below.
6/ Convert The Path Into A Selection
To convert the Path into a Selection: from the left-side Options Box, click the following Selection from Path tab.
This converts the Path into a Selection Marquee - as illustrated below.
Now, right-click over the selected crystal, and from the subsequent drop-down list, click Select and then choose Feather.
And from the subsequent Feather Selection dialogue box, set a Feather Selection By radius of 1 or 2 Pixels - and then click OK.
Shrink And Grow The Selection Marquee Note
You may find Growing or Shrinking your Selection Marquee produces a tighter selection fit. Therefore, for personal results, always experiment with the Shrink and Grow Selection settings - (top menu, then Select then Shrink or Grow).
8/ Invert The Selection Marquee
From the top menu, choose Select and then choose Invert - Ctrl then I. This inverts the Selection Marquee.
Then from the top menu, choose Edit and then choose Clear. Alternatively, tap your Delete Key. This deletes the crystal’s background - as illustrated below.
From the top menu, choose Select and then choose Select None. This removes the Selection Marquee.
Congratulations, you have successfully extracted an object from its background using the Paths Tool, and it is ready to Crop to size, and to optimise and save.
Drop Shadow Tip
My Tutorial Here demonstrates how to apply a Drop Shadow - Filters then Light and Shadow then Drop Shadow.
Now is a good time to save your work a a GIMP XCF File.
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.
To create extra impact, apply a Sharpening Filter of your choice - Filters then Enhance.
My Tutorial Here demonstrates how to resize object/images.
Now you are more familiar with this technique, you can have lots of fun removing backgrounds from your favourite images, objects, or photographs.
Wendi E. M. Scarth. Top of Page.