This GIMP (GNU) tutorial demonstrates how to convert a road into a river using the Free Select Tool. To work along, you are welcome to download the Start Images I am working with Here. Unzip the file and open the Start Images 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
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).
To open the two Start Images onto GIMP’s workspace: from Gimps’ top menu, choose File then Open - Ctrl then O. Now, from the Open Image dialogue box, navigate to the folder where your Start Images reside, then Ctrl-click to highlight both files - and then click the Open tab - as illustrated below.
Now, from the Road Image’s Top Menu, choose Edit and then choose Copy.
And then from the Water Image’s Top Menu, choose Edit and then choose Paste as and then choose New Layer - as illustrated below.
It’s safe to Close the original Road Image - top menu, then File then Close.
In addition, Maximise the Layered Image by clicking its Top Right Maximise tab.
You will find the next step easier to achieve if you enlarge your image by Zooming into it. (I zoomed in twice).
Now, ensure the Road Image’s Layer is active.
And then from the left-side Toolbox, activate the Free Select Tool.
And enter the following Add to the current selection setting into the left-side Options Box.
You are looking to click-and-stretch a “Lasso Line” around the road’s outline - with the aim of isolating it with a Selection Marquee. Therefore, hover your cursor over the left-side
of the road, as illustrated below.
Then left-click your mouse button. Now, in a left-to-right direction, stretch a short Lasso Line around the outside of the road - (illustrated below-left). Then release your mouse button.
Now, continue to stretch-and-click a Lasso Line completely around the outside of the road.
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.
Cancel The Selection Marquee Tip
To cancel the Selection Marquee whilst applying it: press your Keyboard’s ESC Key.
After you have followed the road in a complete circuit, pass your cursor over the exact point where you began, and then left-click.
Left-clicking completes the circuit and transforms the Lasso Line into the following Selection Marquee.
Don’t forget to isolate the following right-side road.
Now that you have isolated the road 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.
From the top menu, choose Select and then choose Feather. From the subsequent Feather Selection dialogue box, enter a Feather Selection by value of 1 pixel, and then click OK -
as illustrated below.
Then from the top menu, choose Edit and then choose Clear. (Alternatively, tap your Delete Key).
The area within the Selection Marquee, (for example the Road) - will be removed. This reveals the underlying River Image, as illustrated below.
Now is a good time to save your Layered Image as a GIMP XCF File - top menu, then File and then Save As.
From the top menu, choose Select and then choose None. And then return your image to its original size using the Zoom Tool or Zoom Command.
8/ Flatten Image
To finish, from the top menu, choose Image and then choose Flatten Image.
Congratulations, your Road to River Conversion is complete, and it is ready to save - top menu, then File then Save As.
Wendi E. M. Scarth. Top of Page.