This GIMP (GNU) tutorial demonstrates how to create depth of field by blurring an object’s background. To work along, you are welcome to download the Poppy 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.
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).
Free Select Tool
Launch GIMP & Organise Its Workspace & Palettes
Open your choice of Start Image onto GIMP’s workspace - File then Open - Ctrl then O.
2/ Free Select Tool For Beginners
Now, from the left-side Toolbox, activate the Free Select Tool.
And enter the following Add to the current selection and Feather edges 2 settings into the left-side Options Box.
The Feather amount is dependent on your image, and the look you are seeking: therefore, when working with your own image, for optimum results, you need to experiment with this setting. (I set Feather of 20 for my example of our cat Harry).
You will find the next step easier to achieve if you enlarge your image by Zooming into it. (I zoomed into my image once).
Tip - Retracing Your Steps
Whilst you are applying the Lasso Line; - and before the Selection Marquee has been applied, to go back one step - press your Keyboard’s Backspace Key. Press the Backspace Key for however many steps you want to go back - (this is for Window PC users, I am unfamiliar with Mac’s). Tapping the Escape Key completely removes the Lasso Line/Selection Marquee.
You are looking to click-and-stretch a “Lasso Line” around the poppy’s outline - with the aim of isolating it with a Selection Marquee. Therefore, hover your cursor over the poppy’s edge. And carefully bit-by-bit, left-click and stretch a Lasso Line around the contours of the poppy.
After you have completed the circuit, pass your cursor over the exact point where you began, then left-click. The Lasso Line will immediately change to a Selection Marquee (moving dotted lines) as illustrated below.
Now that you have isolated the poppy with a Selection Marquee, you are ready for the next step.
Disable the Free Select Tool by clicking any other Tool from the left-side Toolbox. I always activate the Move Tool.
Now, from the top menu, choose Select and then choose Invert - Ctrl then I.
Then from the top menu, choose Filters then choose Blur and then choose Gaussian
Blur. And from the subsequent Gaussian Blur dialogue box, enter the following Blur Radius settings, or experiment, and then click OK.
A higher radius intensifies the blur.
Now, from the top menu, choose Select and then choose Select None.
Your work will benefit from a Sharpening Filter - Enhance then Sharpen.
Congratulations, your Depth of Field Conversion is complete, and is ready to save.
Wendi E. M. Scarth. Top of Page.