Aging a portrait with GIMP

Este artículo también está disponible en Español: Como envejecer un retrato.

There are countless articles available on Internet, explaining how to retouch a portrait and make somebody look younger; basically, what they do is soften the skin and remove wrinkles and other skin defects. In this article I will explain the method I employ to produce exactly the opposite result: aging a portrait. This process enhances the contrast of a photo and highlights the textures; but when applied to a portrait, the effect is that of aging the 'victim'.

Base material

This is the base image, as it left the camera with the standard settings:

Fist I make the conversion from RAW to TIFF, using RawTherapee. I try to mantain as much detail as possible, avoiding under and over exposed zones. The result does not differs a lot from the ofiginal image, I just adjusted the curves, and removed some noise:

Blue channel

Next, I open the file with GIMP. Retouching with portraits, I have noticed that the blue channel tends to be the most interesting one, because it is where the skin defects are more visible:

Consequently, my fist step is duplicate the blue channel and add it as a new layer: open the channels dialog and drag the blue channel over the image window; now I select overlay as the mode for the newly created layer:

High-pass filter

To enhance the contrasts even more, I use a high-pass filter to the new layer, using a relatively large radious (around 32 pixels):

This layer must have an overlay mode, too:

Selective lighting

Our image has the problem that some zones are too dark now; in this example, the tint from the glasses is clearly way too dark, the eyes can hardly be seen. To solve this, I add a new transparent layer, in overlay mode again, and paint with a white brush over the zones that I need to brighten:

The eyes are still a bit too dark for my tastes; and I usually light up the eyes on all my portraits, anyhow. I repeat the previous step: add a new transparent layer, in overlay mode, and paint with a white brush over the eyes:

Corrections and retouching

Now comes the retouching of the hair: I add a new transparent layer, this time in normal mode, and using the clone tool I delete those rebel hairs:

Conversion and exporting

Finally, I export the image to a TIFF file, and open it with RawTherapee again; after some cropping, desaturation, curves, and local contrast enhancement, the final result is:

Because of some strange reason I fail to understand, the main character in this portrait is not fully convinced with the ending results...