This GIMP (GNU) tutorial demonstrates how to desaturate (remove colour) from specific photograph areas. This is otherwise known as Colour Popping. 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.
Understand Blend Modes
Launch GIMP & Organise Its Workspace & Palettes
Open your Start Image onto GIMP’s workspace - File then Open - Ctrl then O.
Now, from the left-side Toolbox, activate the Paintbrush Tool.
And enter the following Colour Mode and Hard Round Brush settings into the Options Box.
Paintbrush Application Note
You can apply the Paintbrush in one sweeping movement. However, for precision, it’s best to apply it one click at a time.
Colour Mode (Important)
For this technique to work, you must remember to change the Paintbrush Tool’s Mode from Normal to Colour. Because the Mode has been changed to Colour, instead of applying the Foreground Colour with the Paintbrush Tool, as would normally be the case; you’ll be removing (desaturating) your image’s colours.
You can quickly adjust the Brush Size by tapping your Keyboard’s Bracket Keys.
You will find the next step easier to achieve if you enlarge your image by Zooming into it.
Bear in mind, when utilising the Zoom Tool, you need to adjust the Paintbrush Tool’s Size according to the amount of Zoom.
Now, left-click over your image, and being careful to avoid painting over the Blue Iris, apply your Paintbrush over your image. Applying the Paintbrush Tool will remove (desaturate) your image’s coloured pixels, as illustrated below.
If you remove coloured pixels in error, then press Ctrl then Z to step backwards, and reapply the Paintbrush Tool.
Avoiding the Blue Iris: go ahead and remove the remaining coloured pixels surrounding the Blue Iris. Remember to step backwards by tapping Ctrl then Z, if necessary. In addition, remember to resize the Brush Size using the Arrow Keys, wherever necessary.
After you have removed the coloured pixels surrounding the Blue Iris, your image will resemble the following.
Congratulations, you are now ready for the next step.
From the top menu, choose Filters then choose Enhance and then choose Unsharp Mask. And from the subsequent Unsharp Mask dialogue box, enter the following settings, or experiment, and then click OK.
Congratulations, your Colour Pop Conversion is complete, and it is ready to save - top menu, then File then Save As.
Wendi E. M. Scarth. Top of Page.