HD Stencils



High Definition Stencils is a graffiti technique invented by Paolo Cirio. The technique digitally creates special stencils for high definition full-color graffiti made with spray paint for the reproduction of pictures and graphics. HD Stencils make use of custom-made software and laser cutters. The final stencils offer a high level of detail through tiny cut-out holes of any geometrical shape. Like subtractive color printing, HD Stencils have the ability to reproduce full color pictures with four stencils for each color channel (CMYB). These stencils can be used on a range of surfaces, from small pieces of paper and canvas to big walls of buildings. The stencils are digitally generated by a simple script coded in Processing, which converts bitmap images in special vector files that can be printed with laser cutter machines. This technique requires a specific process for the preparation of the images for the script, its configuration with manual settings, and the use of the resulting stencils to ultimately make graffiti. The artist released the code and the instructions of his technique with open source license to give everyone the opportunity to learn to create HD Stencils.

The script in Processing as well as the Technique HD Stencils invented and created for this project are released in Open Source with Attribution-NonCommercial-ShareAlike CC BY-NC-SA. This license lets others remix, tweak, and build upon the work non-commercially as long as they credit the artist Paolo Cirio and license their new creations under the identical terms.

High Definition Stencils - How It Works
This is a painting technique rendered with special stencils and spray paint, that begins with the use of custom-made software and laser cutters, using four channels as in subtractive color printing.

Each element of a given image begins as a PSD file so that it can be split into four channels, CMYK, for subtractive color printing. The individual channels are then saved as four JPGs, inverted in negative for each color channel of the image.

A custom-made software script in Processing transforms the JPGs into PDF vector files, ready to be used with the laser cutter. The script in Processing draws a vector grid of tiny holes, which never overlap, and their scale corresponds to the luminance of the pixels from the initial JPG. Through the settings in the script, it is also possible to determine the shape of of the pinholes (circle, triangle, square, star, etc.), regulate the resolution of the grid of the stencil by changing the density, and the maximum and minimum size of the pinholes. Once the PDF is printed through the laser cutter, the resulting stencil is ready to be sprayed. Four stencils will need to be cut from each initial JPG to recreate a full-color painting.

The size of the JPGs, in centimeters or inches, will be the actual final size of the PDFs and of the physical stencil; therefore, size should be taken into consideration for the laser cutter and for printing on various surfaces. The DPI of the source JPGs will only slightly affect the resolution of the stencil, but not the size; even low resolution JPGs (72 DPI) will produce a high quality HD stencil.

With the four resulting stencils, each layer is applied in order of the abbreviation of the channels, spraying the stencils in order of color: first, Cyan; second Magenta; third, Yellow; and last, Black. White background surfaces yield the best results.

The stencils are keyed so that the layers and the offset align, resulting in a full-color image painted on any surface. This is facilitated through the template of the PDF with alignment holes cut by the laser cutter at the same position for each layer.

Project Created: 
August 2012