How to define a custom brush from Adobe.
To define a Custom brush, use one of the selection tools to select the desired area. Then, choose Edit > Define Brush Preset. The brush appears B/W even if you sampled a color area in the image because all brushes are defined as B/W, in order to paint with your selected foreground color. The new custom brush will appear in the Brush Presets panel and can be easily modified (if desired) using the Brush panel (select the brush tip and then modifying any additional attributes).
