I work with punch cards in my home workshop
Posted: Tue Jul 01, 2025 11:13 am
for fun, but I’m also fortunate enough to work with them at Stanford’s Textile Makerspace, where Quinn Dombrowski has been teaching data visualization using textiles on an assortment of knitting machines, looms, and sewing machines. Quinn’s colleague Simon Wiles, a Digital Scholarship Research Developer at Stanford’s Center for Interdisciplinary Digital Research, has worked on a computer-vision approach for converting images of punch cards into data that could be used to generate new physical punch cards. He previously worked on an incredible digitization effort on behalf of the Stanford Libraries to digitize their player piano rolls, which posed related technical challenges, so knitting-machine punch cards seemed like a challenge right up his alley.
When I asked Simon to describe his ideal digitization and preservation workflow for knitting machine punch cards, he said something that surprised me—that the encoded information preserved in magazines and books might color correction a better starting place than the punch cards themselves, depending on the goals of the project. It’s really hard to scan a punch card well. He pointed out that all sorts of things happen to physical punch cards that make them harder to digitize—they get bent or torn (and in the case of the player piano rolls he’s worked on, people repair and modify them in a variety of ways)—all of which are interesting material information about use, but which pose challenges for computer vision. The question of what to do with a hole that has been taped over is not only a creative decision, but also a technical one: will the scan be able to capture that? Do we introduce a new character to represent the tape in the encoding? Not that magazines are foolproof, he stresses—there are plenty of challenges in digitizing shiny paper, especially if one is trying to do it quickly or automatically.
Regardless of source material, Simon stresses the importance of high-quality scans: “From the point of view of posterity: the scan quality is really important—preserve it the best you can: things that are difficult to parse now will only get easier to parse in the future.”
When I asked Simon to describe his ideal digitization and preservation workflow for knitting machine punch cards, he said something that surprised me—that the encoded information preserved in magazines and books might color correction a better starting place than the punch cards themselves, depending on the goals of the project. It’s really hard to scan a punch card well. He pointed out that all sorts of things happen to physical punch cards that make them harder to digitize—they get bent or torn (and in the case of the player piano rolls he’s worked on, people repair and modify them in a variety of ways)—all of which are interesting material information about use, but which pose challenges for computer vision. The question of what to do with a hole that has been taped over is not only a creative decision, but also a technical one: will the scan be able to capture that? Do we introduce a new character to represent the tape in the encoding? Not that magazines are foolproof, he stresses—there are plenty of challenges in digitizing shiny paper, especially if one is trying to do it quickly or automatically.
Regardless of source material, Simon stresses the importance of high-quality scans: “From the point of view of posterity: the scan quality is really important—preserve it the best you can: things that are difficult to parse now will only get easier to parse in the future.”