B&W Conversion with Channel Mixer

The "Channel Mixer" is also a great tool for Black & White conversions:

1. In case of multi-layered image, select the uppermost layer.
2. Open the "Color and Tone" dialog and apply the "Channel Mixer" command.
3. At the bottom of the dialog box that appears, check the "Monochrome" option. The image turns to grayscale.
4. Redistribute luminance with "Red", "Green", "Blue" sliders to achieve the best possible tone and detail.
5. If you want to colorize the image, uncheck the "Monochrome" gadget, in the "Output Channel" menu choose one of the color channels, and play with the color sliders.