Creating More Complex Man-made Materials - Blender 2.6 Cycles: Materials and Textures - page 201

17. Now box select (press B , then click with the left mouse button to drag the
selection on the objects) the ColorRamp1 and ColorRamp2 nodes, the
Multiply1 and Multiply2 nodes, the two Add nodes, and the Multiply4
node; press G and move them to the right, to make room for new nodes
to the left side:
18. Add an RGB Curves node ( Shift + A | Color | RGB Curves ) and paste
it between the Voronoi Texture1 node and the ColorRamp1 node. Re-
name it RGB Curves1 . Click on the curve to add a control point and in
the coordinates slots under the node main window set the X = 0.26111
and the Y = 0.50000 ; click to add a second control point and write X =
0.73889 and Y = 0.51111 .
19. Press Shift + D to duplicate the RGB Curves1 node, paste it between
the Voronoi Texture2 , and the ColorRamp2 nodes and rename it RGB
Curves2 .
20. Go to the ColorRamp1 node and move the white color marker 3/4 to the
left; go to the ColorRamp2 and do exactly the same. Go to the Color-
Ramp3 node and move the white color marker to the middle of the slider.