When a black and white line drawing is scanned in, it may appear as an image with tones of grey - not with definite black and white areas. This would make selecting specific colours on the design very patchy. The design can be easily separated into black and white using the B&W function in the Separate Menu. The black and white function can also be used to separate layers of colour into either 100% or 0% tones of the layer colour.

Separating an image or layer with B&W

1. Scan a line drawing and make it active in AVA. 
2. Duplicate the image layer you are masking by going to Layer Menu > Duplicate. 
3. Go to Separate Menu > B&W and a window will open. In the window, 50% indicates that anything above 50% tone will turn to black and anything under 50% will turn to white.
   
   
4. Enter the percentage you want to set for the separation, click OK and the image will separate to black and white accordingly.
   
   

If the separation does not look satisfactory, go to Edit Menu > Undo (⌘Z) and do the separation again with a different B&W percentage. 

When the results are satisfactory, you can separate the black and white to layers using either the Auto with Create or the Automatic separation methods.