[ Thanks to Dmitri
Popov for this link. ]
“Want to add a vintage effect to your photos? digiKam has all
the tools you need to turn your digital snapshots into vintage
masterpieces. Open the photo you want for editing, adjust exposure,
white balance, and tweak other settings as you would usually do.
The first step in the “aging” process is to add film grain to the
photo. To do this, choose Effects → Add Film Grain. There are
a lot of parameters you can configure, but you don’t have to enable
and tweak them all. You can start with adjusting the Grain Size
parameter as well as trying different values for parameters in the
Luminance Noise section. You can preview the result at any time
using the Try button. Next step is to tweak the color balance to
make the photo look aged. One way to do this is to tweak the color
balance settings, so the photo looks washed out with a slightly
yellow cast imitating aged photo paper. Choose Color → Color
Balance and adjust the Cyan, Magenta, and Yellow parameters to
achieve the desired result.”