. Normally we are describing a shape with color and value, we can also use higher concept, it is more abstract, but bundle with more complex factor into a brush stroke. . The dark side include complementary color purple/yellow and edge of block, to describe more information is this area. So, we don't just copy the grey area of dark, and lift up the lightness in dark area. . This could take a bigger area to enhance the feeling of color, make it more stronger impact, creating