This technique is useful for drawings and photographs as well, although photographs will require that you are quite adept at using levels and other filter tools. One may argue this can be done with the Cutout filter, but if you use that method, it will be obvious that you did as the results are mathmatecial in nature. Also being able to use the techniques described in the process are beneficial for other applications, and allows you more control over the end result.

The workflow of using overlapping layers with the use of Multiple Layer mode is a general method I use to design whole shirts. It makes for on the fly revisions with painting, erasing, and also makes it very simple to maintaining a specific number of colors. It's quite an efficient workflow. Another tutorial is on the way with a detailed description of the workflow.

I take a drawing made with pencil and a Sharpee and...

1. Using the path tool, the shape of the fist is cut out.
2. The cut out is duplicated twice.
3. The duplicated layers above the original are grouped so painting inside the lines becomes less of a concern.

So now we have our setup.
White canvas
Main fist shape layer, which will be saved as the base
A duplicated gray layer grouped to the base
A final duplicate black layer grouped to the base

On the black layer,
1. Using levels (Ctrl-L), the gray pencil areas of the drawing are leveled out.

It is important that you level the white and black to where both pointers are overlapping, thus resulting in a image which is only made of black and white. No grayscale date will exist if you do so. Why is it important? When vectorizing, if there are more than black and white in an image, it will take longer for the vectorizing program to compute as well as creating errant sections of shapes that would not exist if you level out all the grayscale and anti-aliasing. Also an image with no antialiasing which is what happens when you level to black and white, the selections will be cleaner.

If you need a primer on using levels, click here.

After the black layer is leveled, many errant pixels will exist, but you can use a filter to rid of them.

1. Use Filters>Noise>Dust & Scratches filter to clean the image.

Sometimes you may have to do this several times or with a higher radius. Radius and threshold will depend upon the size of the image. Disregard the numeral settings of the filters as it will be different for every image.

2. After you obtain a decent image, use Levels again to adjust the image. In my final image, you will see the areas where there are gray pixels (see image above near knuckoles) have been removed. They were done so by leveling after you run the Dust & Scratches filter.

1. Turn off the black later.
2. Take the gray layer and level up all midtone pixels to black.
3. Repeat the method of using the Dust & Scratches filter to clean errant pixels.

1. Using Brightness/Contrast, increase the brightness to manipulate the black pixels of the gray layer to the desired tone.

1. Turn on the black layer, and Set it to Multiply.

Your image should take shape now, and with some manual painting, clean up the image.

When painting, the workflow setup allows for very quick to revisions. You can color pick by holding ALT while using the brush/pencil tool, so you can paint quickly, BUT ALSO 'erase' by color picking white, and painting to erase. If you use the eraser tool in this workflow, it will actually interfere and not work.

After all cleaning is done, you can take the image, which in this case is white, gray, black, and vectorize easily in a tool such as Illustrator or online with VectorMagic.com.

If you used the levels properly, this image should be easily converted to vector without major differences in the contours.

Raise your fist and resist.