How do I create a split-tone effect using GIMP?

Question

How do I create a split-tone effect in GIMP?

Here is an example of the effect I am looking for.

Answer 1

The effect is not a single color, but a gradient map, where everything between black and white is replaced with a transition between two colors. To create this effect in GIMP, you would first set the active foreground and background colors to the colors that you want to map to black and white, respectively:

The source image should have good contrast for best results:

Make sure that the the active gradient is set to "FG to BG (RGB)", which is the default, then from the "Colors" menu, select "Map>Gradient Map":

(image source)

Answer 2

One way I often achieve a similar look in Gimp is the following:

• Convert your source shot to black and white,
• Duplicate the Layer, so you have to similar b/w layers, I will call them "light" (top layer) and "dark".
• Add a layer mask to the "light" layer (right click layer->'Add Layer Mask') and choose 'Grayscale copy of layer'.
• Select your "light" layer (not its layer mask!), go to 'Colors' -> 'Colorize', choose the hue for the lighter areas of the picture. I tried to mimic the middle one of your example, so I chose a hue value of 5. In this case, set Saturation to its maximum Value. I also had to reduce Lightness by 20.
• Select the "dark" layer, again select 'Colors' -> 'Colorize', choose the hue for the darker areas. Normally you get a good effekt by choosing a hue that is roughly the opposite color (add or substract 180 degree to the light hue). Again to mimic your example I chose hue 266. Saturation to the max, Lightness -20.
• To tweak the shift between light and dark and also the color contrast, you can now play with the layer mask of "light". For that I suggest using the 'Levels' tool in the 'Colors' menu. I increased the contrast of the layer mask by changing the lower Input level to 80 and the upper one to 180. The middle value can be used to get the right dark/light transition.

Here are the original and result:

Image credit: Kelsey's GB Photography