Kuvastin, Kuvastin, on the Wall

Due to the proliferation of compact, low-cost computers and displays, many hobbyist projects have been built to present calendars or task lists in unusual formats. These projects are most commonly created to enhance productivity or make important events highly visible. But that is not always the case. Consider Ilkka Turunen’s unique take on a calendar, for example. Rather than presenting a list of appointments and other events matter-of-factly, this calendar instead gives only a general impression of the day’s events in the form of a work of art.

More than simply informing the viewer, Kuvastin (from the Finnish word for “mirror”) seeks to brighten their day and engage their imagination. The basic concept of the project revolves around feeding a person’s calendar entries into a set of artificial intelligence (AI) tools to first create an appropriate text prompt describing an image to create, then feed that prompt into a generative AI tool to produce the image. This image is then displayed on a large E Ink display, along with the date and a brief, AI-generated caption describing the image.

The hardware used to build Kuvastin is relatively simple, consisting of a Raspberry Pi 4B 4 GB single-board computer. A 10.3 inch, 1872 × 1404 pixel Waveshare E Ink Display HAT is driven by the Raspberry Pi via SPI. And to make the device look presentable for display in the home, an A4-sized picture frame was used to house the components.

Code for the project was written in Python, and utilized the Omni-EPD library for interaction with the E Ink display. By using the Google Calendar API, Turunen was able to get a list of calendar events for any given day. This was included in a prompt that directed GPT-4, via the OpenAI API, to create an appropriate prompt for DALL-E 3. That prompt was then sent to DALL-E 3, again via an OpenAI API to produce the image, which was returned as a base64 encoded string. The program decodes that string and shows it on the E Ink display.

Creating a good prompt can be challenging, so Turunen first came up with a general idea of what the images should look like — something like a 1910's black and white newspaper satirical comic drawing. After generating some images using this description with DALL-E 3, Turunen showed them to Midjourney’s describe feature that gives a text description of an image. These results were used to refine the way the prompt was asked for from GPT-4. In this way, the images were engineered to not only be interesting and entertaining, but also to look great on an E Ink display.

Of course an E Ink display only needs power when the image has to change, so to keep the system up all day so that it could refresh a single time would be very wasteful. As such, the Kuvastin software was programmed to automatically run as soon as the system powers up and the network adapter comes online. After the run, the Raspberry Pi is automatically shut down, after which a power socket timer switch cuts power to the system, until the same time the next day.

Kuvastin is not especially expensive, but it is not quite cheap either, coming in at about $250 in hardware components, as designed. The biggest cost by far is the E Ink display, so if you wanted a smaller calendar, perhaps for desktop use, the price could be brought down a bit. The daily AI prompts will also add to the cost of the system. Turunen estimates those costs will be about $35 per year.

Moving forward, Turunen is exploring ways that the cost of the system could be reduced. Additional upgrades are also being considered, like the possibility of storing the year’s images so that they could later be used in a timelapse video. Be sure to check out the full project write-up if you are considering building your own copy of the device.