First step after importing our image into Darktable is to make our adjustments as if we were developing the image in color (noise reduction, white balance etc...) Below is a screen shot of my initial development and and the adjustments used (sharpen and base curve are automatically applied upon import).
|Imported and Developed as if for a color image final|
Next, we will use the monochrome module in Darktable to do our first conversion. For this module, simply drag the circle around the color pallet until you have the desired look. You can also make the target circle smaller or larger (using the mouse wheel or two finger scrolling on a laptop track pad) which will change the final look of the image. Below is my screen shot of my monochrome conversion with this module (I had shrunk the circle slightly and moved it away from center).
|Monochrome module settings|
Now for the channel mixer module, which is my preference and that in my opinion, is the option with the best results. With the channel mixer selected, we will choose gray as the destination and then simply adjust the three (red, green & blue) channels till we have our desired results. In the screen shot below, you can see the values for my adjustments.
|Channel Mixer module settings|
|Monochrome Module conversion|
|Channel Mixer Conversion|
Your thoughts? Do you have a favorite way to convert to black and white or other methods that have great results not discussed here?