Posterized - the Stencil inspired Tutorial

This tutorial came a long way, because i didnt know how to present it.

I had this interest in stencils since the mid-nineties, long before OBEY and Banksy became part of the mainstream with the streetart-phenomena.

When i still made clothes, i used stencils to get text on jackets, because heattransfer was too expensive.

Today you can find lots of tutorials on youtube, how to create multilayer stencils, there are even filters that imitate the Obama Hope poster effect.

One of the easiest ways to make stencils is by playing with the contrast or using the posterize filter. In Photoshop you have the Cutout filter, which has the advantage of simplifiying the edge.
And if you are a true artist you can of course draw or trace a stencil by hand or in a vector program, preferably with a tablet.

I looked into all of these methods, and im still experimenting.

One of my earlier hunts for research lead me to this tutorial by goblin, who has a very interesting opinion about the difference between Gimp's Posterize, in comparison to the Photoshop filter, which in return inspired me to do my own research.
I discovered, both the mighty saulgoode and RobA had written scripts which adress the problem of the Posterize filter.

saulgoode's Quantize: http://chiselapp.com/user/saulgoode/repository/script-fu/wiki?name=sg-quantize

RobA's Posterized Indexed (poster_indexed.scm): http://www.silent9.com/incoming/scripts/

This tutorial is not about how to make a stencil, but create an effect, that has a stencil aesthetic to it.

Before you can start, you have to install the 'Quantize' script by copying the scm-file into your user/script folder.

1. Get an image and crop it the way you like. I got mine from wikipedia.

2. Remove the background with the method you like best. I made a path in Inkscape and imported it into Gimp.

Its important that you have a way of calling up a selection later in the tutorial.
If you have a path, you are good to go.
If you rendered your image with a different method, you could save the alpha selection into a channel.

3. Add a layermask from selection.

04. Put a new white layer under the original image, so that we have a background for contrast reasons.

05. Make sure the Original Image is selected, then go to G'MIC → Repair → Smooth [bilateral] and apply with the default value. Make sure you set the 'Output Mode' on the left, to 'New Layer' !

06. Put the original Image under the white background layer and turn it off.

07. With the bilateral smoothed layer selected, apply Colours → Quantize.
This will reduce the number of colours. Saulgoode's Quantize script will give you better results than Gimp's Posterize, although the idea behind both tools is similar.

Another way to get quantized colours, is changing the Mode (from the Image Menu) to Indexed. But you have to convert the Indexed image back into RGB.

Thats why in my opinion the Quantize script is the best tool for what we want, plus we have a built in smoothing option, which is excellent for getting simplified edges.

08. For some comic style lines, duplicate the original images and send it to the top. Delete the layermask and then duplicate the layer again.

Gaussian Blur the top layer by 20px, then set the Mode to 'Divide' !

09. Merge the top layer down and apply 'Selective Gaussian Blur'.
This will get rid of the noise and midtones.

10. Apply 'Threshold', so that you get a nice pencil effect.
Clean up your result with a white brush where necessary.

Rename the layer to 'Pencil'.

Set the Mode to 'Multiply' to get rid of the white.

11. For an outline, call up your selection and stroke it on a new transparent layer.
I used a line width of 2px and it doesnt matter if its jaggy, because we are gonna process it some more.

a.) Apply: Filters → Noise → Spread 5px
b.) Gaussian Blur by 5px
c.) apply an Alpha Curve. This will give you an Andy Warhol blotted line effect.

12. I touched up the Pencil and Quantize layer a bit with a brush, where necessary.
Applied a Gaussian Blur of 2px to the Quantize layer because i didnt like the jaggy edges.
This is what we got so far.

13. Now for a hatching effect, we need to create a grid first.

a.) Duplicate the original image, send it to the top. Name it layermask.
b.) Invert the colours.
c.) Create a black layer and put it under the Layermask layer.
d.) Merge down.
e.) copy that layer.
f.) apply a layermask to the Grid layer.
g.) with the layermask of the Gridlayer selected → Paste and anchor !

14. Now with the layermask selected, call up the Levels or Curves Tool (whatever you like better). And manipulate the colours in the layermask, so that the Grid looks more like hatchings.

15. For even darker hatchings, i will create another grid layer, but this time twice as big.
Repeat the Grid filter, then rotate the layer by 45°. Apply layer to imagesize.
a.) apply a black Layermask to the gridlayer
b.) on the Quantize layer, select the dark gray with the 'Select by Colour Tool'
c.) invert the selection
d.) with the layermask selected fill the selection with white !
e.) deselect
f.) call up your saved selection
f.) Gaussian Blur the layermask by 30px for a smoother transition and deselect.

16. Copy a bunch of text, call up the Text Tool and draw a selection around the image, then paste.
Adjust the textsize and alignment until the whole image is filled.

Create a new white layer under text and merge both layers.

Apply the G'MIC → Black & White → Pencil Filter at default values.

Call up your saved selection and apply a layermask from selection (make sure its inverted).
Then deselect.

Adjust Opacity.

16. For a border, increase the Canvas Size by 20 px (make sure you hit the centered button) and create a new black layer at the bottom of all layers.