Emacs's hexl-mode does this, incidentally, though annoyingly by default it makes all faces the same color. I never understood why it defines the faces but then doesn't customize them.

I think semantic coloring (based on structure) is more useful. Also (can't help as someone working with z/OS), if you really want to make hex output readable, I recommend using big-endian machine.

I've started doing this with hashes in a CLI I'm working on. For slow prints, it's somewhat helpful https://asciinema.org/a/aD38Pk88CZgSZqtq but for debug dumps with many many hashes it really helps readability and tracking hashes across lines.

When I read this article a few days ago it inspired me to create my own hex viewer : https://ar-ms.me/thoughts/3sl-a-sweet-hex-utility/

The cool thing about it imo (outside of colors) is a `--windows` flag. Which separates the hex view into partitions: so `-w 2:-3:5` shows the first two bytes on a line, then skips three bytes, then shows the next 5 bytes on a line, then the rest of the file. Easy to use combined with a terminal's up arrow.

That said, even colored these dumps still feels unappealing to me — so yes this is admittedly subjective gut jumping in the conversation. I get that occult form can also be an attractive force.

The post put on the table an interesting point about how to improve the presentation layer to fit what’s human cognition is good at spotting (in general, or at least for the expected audience with some training). And it does start proposing something with these color schemes. But isn’t it kind of missing the forest for the tree? Actually why do we even have rendering with [012345678ABCDEF], when a specific set of (colored/imaged?) glyphs would be able to make more obvious what’s on the table? Or even beyond the hexadecimal grouping, wouldn’t be more relevant to render something "intuitively" far more easy to grap without several layer of internalized interpretation through acculturation?

I really like hexyl [1], which does this by default.

https://github.com/sharkdp/hexyl

This article made me think how I could use similar techinques to colour code the data in database tables. Has anyone here tried that and has some recommendations where to start, etc.?

If you analyze binary files often, I highly recommend binvis - http://binvis.io/. It creates a colored minimap for files it loads and has two available arrangements. Pixel color is based on range of bytes, eg ASCII/null bytes/FF bytes. Besides, it’s a pretty basic hex viewer that runs in your browser. The minimap is extremely powerful for identifying interesting areas and patterns in unknown data.

Everything should try do some basic syntax highlighting IMO. Not too much, or it just becomes a sea of formatting that doesn't help at all. It is surprising how much difference a little splash of colour makes. If possible, always include configuration options for the user though, so those with colour-blindness issues can tweak things to their needs, those who are just fussy can make the output fit with their finely adjusted system-wide colour schemes¹, and even better, where you can, allow bold/italic/other as well as colours so that those who barely see colour at all can play too.

Of course none of this helps those using screen-readers and other tech, so make sure that all your fancy colouring & such is additive so if it is all “lost” no meaning is absolutely lost with it.

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[1] Some people can be very vocal about this, more so than if highlighting isn't possible at all. If you give any output formatting they'll expect you to match, or be able to be made to match, their preferred style.