Tutorial: computeraided Outlines
Program: Corel PhotoPaint
Operating system: Windows
Inpudevice: Wacom Tablet
Everybody, who wanted to color a scanned image know this: grey pixel, grubby lines. The answer is easy: Let the graphic Programm of your choice sort it out for you.
How it works:
To get a good line picture, which you could color afterwards without drawing it again on PC, you need 2 steps which are equal in most graphic programms.
You should keep in mind to scan an image, whose lines are in a good contrast with the background. Perhaps you should ink the drawing with a fineliner.

Step 1:
At first we have to convert the scanned drawing into a black/white picture - yes I know that we want to apply colors afterwards ;)
The algorithm works as follow: It looks on the value of every Pixel (between 0 and 255 - colorpictures got 3 channels each with the range of 0 - 255. It take the midpoint.)Is the value smaller than the trashold the new pixel gets black otherwise it get white.
We eliminate all other color values.

Step 2:
Now we got a nice linepicture but unfortunatly no more color. But we can change this - just set the range from b/w to RBG color again: