Convert bitmap in black & white

Monochrome called black & white or 1 bit color image. Their are two types mode for convert color image into Greyscale and Black & White. But I am telling you about black & white mode & their kinds. here are the conversion method : Line Art, ordered, jarvis, stucki, floyd-steinberg, halftone & cardinality-distribution.

Select a bitmap & go to Bitmaps / Mode / Black & White (1-bit)...

See below figure for different type of modes.

To color a 1 bit image (monochrome) bitmap 

1. Select a bitmap use of Pick tool. 
2. Right-click a color on the color palette to change the color of the foreground. 
3. Click a color on the color palette to change the color of the background. 
4. You can add effects also.

See this video