Photoshop offers many methods to color in inked drawings. In most of my work, I use different layers for the line, color, highlights, and shadows. Here I try to experiment with different methods to see how they look and feel. In the 1st example (top left) I use 2 layers, layer 1: normal color with a 50% opaque brush, and layer 2: black line . The 2nd example, I use 4 layers, layer 1:one tone of gray, layer 2: one tone of color (using photoshops color layer mode), layer 3: normal color with a "pencil" brush, and layer 4: black line. Example 3: The 1st layer is many tones of gray followed by a 2nd layer of gray highlights and shadows, layer 3: flat color with photoshops color layer mode, and layer 4: black line. With example 4, I used the same base of grays for layer 1 and 2 used in example 3. Then followed by "pencil" brush color with photoshops color layer mode, and layer 4: black line. The last example I used reversed colors for a "solarized" look and finally the original sketch.