Subpixel Rendering For Impossibly Small Terminal Text

When it comes to text, how small is too small? The experts say a six point font is the minimum for readability, but [James Bowman] shows us that you can get away with half of that. In this fascinating experiment, James attempts to display 40 characters on a 24 mm x 24 mm LCD with a resolution of 240 x 240 to show a serial terminal or other data using the "TermDriver2" USB-to-Serial adapter.

With 24 lines, that's a line per millimeter: very small text. To be precise, it's three points - half what the experts say you need. Diving this up into 40 columns gives a character cell of six by nine pixels. Is it enough? Not by itself, no. That's where the hack comes in: sub-pixel rendering.

A "white" pixel on an LCD is actually three elements: a red, a green, and a blue subpixel, stacked side-by-side. By driving each of those subpixels independently, 240 pixels now becomes 720 - plenty for a 40 column terminal. But how did James pull off this sub-pixel rendering? In general terms, he was able to achieve this impressive feat while keeping the font as legible as possible.

However, it's worth noting that the colored fringe around the characters can be uncomfortable to look at for some people - and then there's the physical size of the characters being 1 mm tall. If this trick were being used on a larger display with a 240-wide resolution, we'd say "yes, very legible, good job!"- but at this size? We hope we can find our reading glasses. Still, it's a neat trick to have in your back pocket for driving low-resolution LCDs.

But sub-pixel rendering is not just limited to improving legibility - it's also used for pixel art. The fact that James was able to achieve this impressive feat demonstrates the creativity and ingenuity of DIY electronics enthusiasts like himself. We can only imagine what other amazing projects he might be working on in his spare time.

As we continue to push the boundaries of what is possible with low-resolution displays, it's exciting to think about the possibilities that sub-pixel rendering opens up. Whether you're a seasoned hacker or just starting out, this technique is definitely worth trying - and who knows, you might just discover a new passion for DIY electronics.