This GIMP (GNU) tutorial demonstrates how to change the colour of irises. 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.
Free Select Tool
Understand Blend Modes
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).
Now, create a New Transparent Layer by clicking the Layer Palette’s Create a new layer tab, as illustrated below-left. Then click OK to the subsequent New Layer dialogue box, as illustrated below-right.
For accuracy, Zoom into the eyes: - top menu, then View then Zoom. (I zoomed in three times).
Shift+Plus Key And Minus Key Tip
To quickly zoom in or out of an image - tap your Keyboard’s Shift+Plus Key or the Minus Key, respectively.
If necessary, you can navigate your image using the Right-side and Lower Scroll Bars.
From the left-side Toolbox, activate the Free Select Tool.
And enter the following Add to the current selection and Feather 2 settings into the left-side Options Box.
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.
You are looking to click-and-stretch (one at a time), a “Lasso Line” around both irises - with the aim of isolating them with a Selection Marquee. Therefore, click and stretch a Lasso Line around the first iris in a complete circuit. Then pass your cursor over the exact point where you began, then left-click - as illustrated below-left. This converts the Lasso Line into a Selection Marquee, as illustrated below-right.
Now, isolate the second iris with a Selection Marquee, in exactly the same way as you did with the first. After you have completed this both irises will be isolated with a Selection Marquee - as illustrated below
After you have have isolated both irises with a Selection Marquee, you are ready for the next step.
To preserves the eye’s luminosity, it is crucial that you change the New Transparent Layer’s Blend Mode from Normal to Colour. If the Blend Mode remains with its default Normal setting, the following solid colour will be applied to the selected iris.
4/ Change The Transparent Layer’s Blend Mode To Colour
Therefore, from the Layers Palette, change the Transparent Layer’s Blend Mode from Normal to Colour. (Layers, Blend Modes).
Now, set the Foreground Colour Swatch to a colour you would your irises to be. I am choosing a vibrant Lilac.
Then from the left-side Toolbox, activate the Bucket Fill Tool.
And enter the following FG Colour Fill settings into the Options Box.
Now, (still working on the Transparent Layer). Left-click inside the Selected Irises to fill them with the Foreground Colour.
Because you have applied the colour to a separate Layer from the photograph, if you prefer, you can alter the Lilac Colour’s appears. For example, lowering the Colour Fill’s Layer Opacity will fade the iris colours.
Gradient Fill Note
If you prefer, return your image to its pre-colourised state by clicking Ctrl then Z. And fill the Selected Irises with a vibrant Gradient using the Blend Tool - as demonstrated in my tutorial here Chapter 4.
Now, from the left-side Toolbox, activate the Eraser Tool.
And set the following Hard Round Brush settings into the Tool Options Box.
Then apply the Eraser Tool to the irises’ colourised white irises - as illustrated below.
You can quickly change the Brush Size by tapping your Keyboard’s Square Bracket Keys.
It’s a good idea to save your Layered Image as GIMP XCF File.
(Return your image it’s original size).
To finish, from the top menu, choose Image and then choose Flatten Image.
Congratulations, your image is complete, and it is ready to save - top menu, then File then Save As.
Now you are familiar with this technique, you can have lots of fun changing iris colours.
Wendi E. M. Scarth. Top of Page.