This GIMP (GNU) tutorial demonstrates how to apply a rainbow to a photograph.
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.
Scale Tool Tutorial
Eraser Tool Tutorial
Understand Blend Modes
Resize Two Layered Images Equally
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.
Now, from the Rainbow Image’s Top Menu, choose Edit and then choose Copy.
Then from the Scenic Start 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 (black), Rainbow Image - top menu, then File then Close.
Now you have Layered your two Start Images, you are ready for the next step.
Resize Two Images Note
Although not necessary for this tutorial: my Resize Two Images Equally Tutorial Here, demonstrates how to resize Two Layered Images, equally.
Now is a good time to save your Layered Image as an GIMP XCF File.
4/ Understand Blend Modes
Now, change the Top Layer’s (The Rainbow Image’s) Blend Mode from Normal to Lighten Only, or Screen - as demonstrated below.
Lighten Only Blend Mode Example
Screen Blend Mode Example
For personal blends, it’s important to experiment with different Blend Modes and Layer Opacities.
Now, working between the Move and Scale Tools, (Beginner Tutorials), Resize and Reposition the Rainbow image over the photograph. Perhaps, Duplicating the Rainbow Layer, and creating a second rainbow, if you so wish.
Eraser Tool Note
Unwanted Rainbow pixels can be removed using a Soft, Round Eraser Tool Brush.
You can quickly Resize the Eraser Brush’s Size by tapping the Square (Outer) Bracket Keys.
Prior to Flattening your image, you may want to save it image as an XCF File.
6/ Flatten Image
When you happy with your work: from the top menu, choose Image and then choose Flatten Image.
To create extra impact, apply a Sharpening Filter of your choice - Filters then Enhance.
Congratulations, your Rainbow Conversion is complete, and it is ready to save - top menu, then File then Save As.
Now you are more familiar with this technique, you can have lots of fun applying rainbows to your favourite images.
Wendi E. M. Scarth. Top of Page.