Send Images To Your Terminal With Rich Pixels

September 13, 2025 by Donald Papp 10 Comments

[darrenburns]’ Rich Pixels is a library for sending colorful images to a terminal. Give it an image, and it’ll dump it to your terminal in full color. While it also supports ASCII art, the cool part is how it makes it so easy to display an arbitrary image — a pixel-art rendition of it, anyway — in a terminal window.

How it does this is by cleverly representing two lines of pixels in the source image with a single terminal row of characters. Each vertical pixel pair is represented by a single Unicode ▄ (U+2584 “lower half block”) character. The trick is to set the background color of the half-block to the upper pixel’s RGB value, and the foreground color of the half-block to the lower pixel’s RGB. By doing this, a single half block character represents two vertically-stacked pixels. The only gotcha is that Rich Pixels doesn’t resize the source image; if one’s source image is 600 pixels wide, one’s terminal is going to receive 600 U+2584 characters per line to render the Rich Pixels version.

[Simon WIllison] took things a step further and made show_image.py, which works the same except it resizes the source image to fit one’s terminal first. This makes it much more flexible and intuitive.

The code is here on [Simon]’s tools GitHub, a repository for software tools he finds useful, like the Incomplete JSON Pretty Printer.

What Is The Fourier Transform?

September 12, 2025 by John Elliot V 20 Comments

Over at Quanta Magazine [Shalma Wegsman] asks What Is the Fourier Transform?

[Shalma] begins by telling you a little about Joseph Fourier, the French mathematician with an interest in heat propagation who founded the field of harmonic analysis in the early 1800s.

Fourier’s basic insight was that you can represent everything as a sum of very basic oscillations, where the basic oscillations are sine or cosine functions with certain parameters. [Shalma] explains that the biology of our ear can do a similar thing by picking the various notes out from a tune which is heard, but mathematicians and programmers work without the benefit of evolved resonant hairs and bone, they work with math and code.

[Shalma] explains how frequency components can be discovered by trial and error, multiplying candidate frequencies with the original function to see if there are large peaks, indicating the frequency is a component, or if the variations average to zero, indicating the frequency is not a component. [Shalma] tells how even square waves can be modeled with an infinite set of frequencies known as the Fourier series.

Taking a look at higher-dimensional problems [Shalma] mentions how Fourier transforms can be used for graphical compression by dropping the high frequency detail which our eyes can barely perceive anyway. [Shalma] gives us a fascinating look at the 64 graphical building blocks which can be combined to create any possible 8×8 image.

[Shalma] then mentions James Cooley and John Tukey and the development of the Fast Fourier Transform in the 1960s. This mathematical tool has been employed to study the tides, to detect gravitational waves, to develop radar and magnetic resonance imaging, and to support signal processing and data compression. Even quantum mechanics finds use for harmonic analysis, and [Shalma] explains how it relates to the uncertainty principle. The Fourier transform has spread through pure mathematics and into number theory, too.

[Shalma] closes with a quote from Charles Fefferman: “If people didn’t know about the Fourier transform, I don’t know what percent of math would then disappear, but it would be a big percent.”

If you’re interested in the Fourier transform and want to dive deeper we would encourage you to read The Fastest Fourier Transform In The West and Even Faster Fourier Transforms On The Raspbery Pi Zero.

Header image: Joseph Fourier, Attributed to Pierre-Claude Gautherot, Public domain.

Everything In A Linux Terminal

September 10, 2025 by Al Williams 49 Comments

Here at Hackaday Central, we fancy that we know a little something about Linux. But if you’d tasked us to run any GUI program inside a Linux terminal, we’d have said that wasn’t possible. But, it turns out, you should have asked [mmulet] who put together term.everything.

You might be thinking that of course, you can launch a GUI program from a terminal. Sure. That’s not what this is. Instead, it hijacks the Wayland protocol and renders the graphics as text. Or, if your terminal supports it, as an image. Performance is probably not your goal if you want to do this. As the old saying goes, “It’s not that the dog can sing well; it’s that the dog can sing at all.”

If, like us, you are more interested in how it works, there’s a write up explaining the nuances of the Wayland protocol. The article points out that Wayland doesn’t actually care what you do with the graphical output. In particular, “… you could print out the graphics and give them to a league of crochet grandmas to individually tie together every single pixel into the afghan of legend!” We expect to see this tested at an upcoming hacker conference. Maybe even Supercon.

We generally don’t like Wayland very much. We use a lot of hacks like xdotool and autokey that Wayland doesn’t like. We also think people didn’t understand X11’s network abilities until it was too late. If you think of it as only a video card driver, then you get what you deserve. But we have to admit, we are humbled by term.everything.

The Most Personalized Font Is Your Own Handwriting

September 6, 2025 by Tyler August 58 Comments

When making a personal website, one will naturally include a personal touch. What could be more personal than creating a font from your own handwriting? That’s what [Chris Smith] has done, and it looks great on his blog, which also has a post summarizing the process.

Like most of us [Chris] tried to use open-source toolkits first, but the workflow (and thus the result) was a bit wanting. Still, he details what it takes to create a font in Inkscape or Font Forge if anyone else wants to give it a try. Instead he ended up using a web app called Calligraphr designed for this exact use case.

Above is hand written; below is the font. Aside from the lighting the difference isn’t obvious.

Fair warning: the tool is closed-source and he needed to pay to get all the features he wanted — specifically ligatures, glyphs made from two joined letters. By adding ligatures his personalized font gets a little bit of variation, as the ‘l’ in an ‘lf’ ligature (for example) need not be identical to the stand-alone ‘l’. In a case of “you get what you pay for” the process worked great and to the credit of the folks at Calligraphr, while it is Software-As-Service they offer a one-time payment for one month’s use of the “pro” features. While nobody likes SaS, that’s a much more user-friendly way to do it — or perhaps “least-user-hostile”.

All [Chris] had to do was write out and scan a few sheets that you can see above, while the software handled most of the hard work automagically. [Chris] only had to apply a few tweaks to get the result you see here. Aside from websites, we could see a personalized font like this being a nice touch to laser cut, CNC or even 3D printed projects. If you don’t want a personalized touch, the “Gorton” lettering of retro machinery might be more to your liking.

Capture And Plot Serial Data In The Browser

September 5, 2025 by Jenny List 5 Comments

If you’re working with a microcontroller that reads a sensor, the chances are that at some point you’re faced with a serial port passing out continuous readings. The workflow of visualizing this data can be tedious, involving a cut-and-paste from a terminal to a CSV file. What if there were a handy all-in-one serial data visualization tool, a serial data oscilloscope, if you will? [Atomic14] has you covered, with the web serial plotter.

It’s a browser-based tool that uses the WebSerial API, so sadly if you’re a Firefox user you’re not invited to the party. Serial data can be plotted and exported, and there are a range of options for viewing. Behind the scenes there’s some Node and React magic happening, but should you wish to avoid getting your hands dirty there’s an online demo you can try.

Looking at it we’re ashamed to have been labouring under a complex workflow, particularly as we find this isn’t the first to appear on these pages.

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A hand holding a One ROM with a Commodore 64 in the background

One ROM: The Latest Incarnation Of The Software Defined ROM

September 3, 2025 by John Elliot V 25 Comments

Retrocomputers need ROMs, but they’re just so read only. Enter the latest incarnation of [Piers]’s One ROM to rule them all, now built with a RP2350, because the newest version is 5V capable. This can replace the failing ROMs in your old Commodore gear with this sweet design on a two-layer PCB, using a cheap microcontroller.

[Piers] wanted to use the RP2350 from the beginning but there simply wasn’t space on the board for the 23 level shifters which would have been required. But now that the A4 stepping adds 5 V tolerance [Piers] has been able to reformulate his design.

The C64 in the demo has three different ROMs: the basic ROM, kernel ROM, and character ROM. A single One ROM can emulate all three. The firmware is performance critical, it needs to convert requests on the address pins to results on the data bus just as fast as it can and [Piers] employs a number of tricks to meet these requirements.

The PCB layout for the RP2350 required extensive changes from the larger STM32 in the previous version. Because the RP2350 uses large power and ground pads underneath the IC this area, which was originally used to drop vias to the other side of the board, was no longer available for signal routing. And of course [Piers] is constrained by the size of the board needing to fit in the original form factor used by the C64.

The One ROM code is available over on GitHub, and the accompanying video from [Piers] is an interesting look into the design process and how tradeoffs and compromises and hacks are made in order to meet functional requirements.

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The (Data) Plot Thickens

August 28, 2025 by Al Williams 35 Comments

You’ve generated a ton of data. How do you analyze it and present it? Sure, you can use a spreadsheet. Or break out some programming tools. Or try LabPlot. Sure, it is sort of like a spreadsheet. But it does more. It has object management features, worksheets like a Juypter notebook, and a software development kit, in case it doesn’t do what you want out of the box.

The program is made to deal with very large data sets. There are tons of output options, including the usual line plots, histograms, and more exotic things like Q-Q plots. You can have hierarchies of spreadsheets (for example, a child spreadsheet can compute statistics about a parent spreadsheet). There are tons of regression analysis tools, likelihood estimation, and numerical integration and differentiation built in.

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