It is a good idea to use colors to divide up the drawing into parts, which then makes it easier to swap between selections later on. It is possible to do this with the brush and eraser tools but you can use the Fill Tool to color in bounded areas of the line drawing in one go.
You can use the Fill Tool where there are closed sections of the line drawing. Next, we need to add a layer for the basecoat.
Open the layer window and tap the (1) + button to add a basecoat layer. Next, tap the (2) layer that you added to make it the Current Layer.
Place the basecoat layer underneath the line drawing. Change the order of the layers by dragging the (1) Thumbnail (small image) down.
Tap the Bucket button from the (1) Tool Selector Window to select the (2) Fill Tool.
Tap the (1) button to open the Fill Property Window.
Fill takes the color or threshold of the start point and then fills a space lower than the threshold. If you want to set the line drawing layer as the boundary then you should select the boundary as (2) Opacity. If you want to set a part of a colored layer or photo as the boundary you should select Color. Here, we want to set the line drawing as the boundary so tap (2) Opacity. The boundary percentage is the setting which defines the extent to which the an area may differ from the start point transparency before it is recognized as the boundary. Setting it to 0% means that only areas exactly the same transparency as the start point will be filled. Setting it to 90% means that, for instance, if the start point was totally transparent (100%) areas that were almost totally opaque (10%) would still be filled. Making the boundary 100% would mean that the whole layer would be filled, regardless of its transparency. Here, we will set the (3) boundary to 60%.
Next, select Current to set the Current Layer as the Reference Layer and then fill the Current Layer. If you have selected Specific the layer row selected below will be used as the reference layer and the color fill will be applied to the Current Layer. Selecting the Canvas will reference an image created by the merging of all layers and apply the color fill to the Current Layer.
Here we want to use the line drawing as reference and fill the Current Layer. Select (4) Specific and tap the (5) Layer Row to select the line drawing layer.
Select a color from the color window. Select a flesh color by dragging the (1) Hue Picker and the (2) Saturation/Brightness Picker in the HSB box.
Now, let’s paint the skin. Tapping in the middle of an area bounded by lines will fill that area with color. If you go over the edges or fill the whole screen with color just tap the Undo Button to go back one step.
The above shows the result of using the Fill Tool and changing the color to fill in the skin and boots.
The above screenshots show the difference between setting the boundary to 10% and 90%. You can see that the higher the boundary threshold the more the inside will be filled. When there are gaps in the line drawing it is a good idea to set the threshold as high as possible.
The Fill properties may be a little difficult to grasp. People often complain that the Fill Tool is buggy and fills in the whole screen. If you think that you still do not really understand the tool, just set the boundary to Color, 10%, reference canvas and you should get the results you want.
After finishing applying the fill open the layer window. It should look something like the above screenshot. (1) is the Line Drawing Layer, (2) is the Basecoat Layer, and (3) is the Draft Sketch Layer. Applying the color fill like this makes it easy to select parts with the Magic Wand later.