Forget Filters, Get a Hand-Drawn Print From This DIY Camera

In the world of photography, what’s old is new again. Ultra-high-resolution digital photography offers the best quality images you will get from any camera. However, the best isn’t always what people want. Some people find digital images to be too ephemeral, so there has been a resurgence of interest in instant cameras. Having a physical print to hold and put in a photo album has a different kind of appeal that cannot be matched with more pixels.

Jens of the YouTube channel Strange Inventions loves the idea of having physical prints of photos. But he also wanted something different that is more interesting, artistic, and thought provoking. With nothing matching his requirements commercially available, he settled on a plan to build a camera pen plotter. This is something that has been done many times before, but Jens’ build comes with a unique twist — it is just as portable as any traditional camera.

To bring this idea to life, a 3D-printed frame and mechanism was designed to move a pen over a small piece of paper on command. A Raspberry Pi Zero single-board computer controls its movement with the help of a servo control board and three servos. This arrangement allows for control over the x- and y-axis, and also makes it possible for the pen to lift and lower. A camera module snaps pictures for the device to draw.

That was the easiest part of the build; getting the software right was a much bigger challenge. After lots of testing, Jens found that using OpenCV’s contour detection algorithm was the best way to turn an image into line art that the plotter could draw. The raw results were too rough for use, however. Jens discovered that reducing the resolution of the input images helped somewhat. The software was also designed to iterate on each image, adjusting the detection sensitivity until a set number of line segments was detected.

As a final step, software called Potrace was used to smooth the jagged lines of the contour detection algorithm. Jens then used inverse kinematics to turn the line art into a series of movements for the servos.

The final result is by no means perfect — but that is kind of the point. If you want perfect, use your phone. If you want style, use Jens’ portable camera pen plotter.