There are several ways to convert a picture to black and white with Darktable.
- Using the monochrome module,
- using the RGB colour balance module, and
- using the colour calibration module.
Monochrome & RGB Balance Modules
There is not too much to say about this approach. Both modules will desaturate the colours leaving you with a little room to manipulate the greys. The only difference between these two approaches is that the monochrome module can emulate the filters to control the blacks.
The Colour Calibration Module
In my opinion, the colour calibration module is the best. It gives control about how much each colour channel will affect the final monochrome image.
With this said, let's see the following video explaining what was done.
After having your colourful picture ready:
- Convert RGB channels to grey with the Colour Calibration module. Use this module to control how you want to get your grey tones. There is no recipe for what to do this. In the specific case of this photo, because there is a lot of grey, some red (because of the browns) and little blue the tone that took more percentage is the blue. This gives a darker image result.
- Increase contrast with the Sigmoide module. Disable the RGB filmic module and use the sigmoidal one. The sigmode control will give you more details on the highlights. Adjust the contrast higher value than you usually do for the colour photo. Remember that black and white photos are all about the contrasts.
- Increase details with the local contrast module. The local-contrast module has a local tone HDR preset. Use it as a starting point and adjust the highlights and shadows to a level you like.
- Add a slight colour detail with the split-toning module. A nice black-and-white photo usually is not strictly black and white. Nice black-and-white photos usually have a little tint. Use this module to add a small touch of colour. Usually, blue for the shadows (cold colour) and yellow (warm colour) for the highlights; light and dark browns work as well. You will see the difference.
- Highlight your subject with a mask in the exposure module. This is also called doge and burn; by increasing the exposition on the key subject you will highlight its presence. You can highlight and darken as many objects in your photo; use the mask tool to do this.
Happy editing and good luck!
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