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I am doing a lot of black and white postprocessing lately, inspired by some of my photos, by other photos I saw and by the two books about black and white photography and post processing I read. They are writing a lot about toning black and white photographs in those books, especially with selen and sepia colors. This lead me to experiment a little bit with GIMP to try to get similar effects.
There are some toning examples and tutorials about how to tone photographs with one additional color (apart from black), and there is a GIMP script written by Alexios named “Duotone” doing this.

I took a similar approach and tried to tone black and white photographs with both, selen and sepia color, at once. The idea is to tone the darker areas with one and the brighter areas with another color keeping the completely white areas white and the black areas black. Using this technique carefully you can increase visibly the contrast of black and white photos without making them look colored. In some cases the observer won’t even notice that there is any color in the image while not looking explicitly for color. Additionally it will give a bit of old (or “darkroom”) feeling to the images.


Here my steps explained shortly for GIMP, should be easy in other applications supporting layers, masks and layer modes, too.

  • Create a layer and fill it with the color you want to use for toning the brighter areas and set it to “Color” mode. Add a layer mask with the grayscale of the original photo to it.
  • Create another layer, fill it with the dark toning color and set it to “Color” mode, too. Then add a layer mask to this layer using the negative of the mask used before.
  • Reduce the opacity of both layers to something between 5 and 30. If you use saturated fill colors you won’t need more normally. Use it carefully.

You can modify the curves afterwards. The duotone script works with a toning curve with its hightest point in the middle and going down to 0 at the very left and the very right side. Instead of masking the darker toning color with the negative of the image, you could use the normal image there too and then apply curves like the curve used in the duotone script, but moved a little bit to the left (or to the right for the brighter toning color).

By the way, the sharpening layer used in this file is set to “Value” mode. This way you sharpen the image without touching the original layer nor the toning layers. You can download the sample GIMP xcf image file I created. And the border is created with Alexio’s Full Frame Script.

Based on the duotone script mentioned above I created a script for the GIMP which does exactly those steps. As default color values I used the more saturated colors of a selenium/sepia tone and a bluish, like cyanotype. After running this script you’ll need to adjust the opacity of the toning layers.

You can install it the same way as Alexios is documenting for his script.


Rolf, who is hosting the Meet The Gimp Video Podcast will perhaps include this technique in one of his shows.

Update: I corrected what I said about selenium. Selenium will give a brown-reddish tone, not a cold one. See http://en.wikipedia. … graphic_print_toning and the documentation about Ilford Multigrade Paper. Here you can find a lot of possible toning colors. Thanks, Frank, for the hint.
Although I am a bit irritated as I find a lot of bluish photos tagged with “selenium”…

Update 2: Rolf wrote about this post. From the comments there I got another link to a site of toning examples: http://www.gimpguru. … orials/SampleToning/. Great.