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Evaluating and creating dithering algorithms for epaper laptop

peterme.net

3 pointsby PMunch6 ay önce0 comments

Ask HN: Does anyone have a good corups of different Markdown?

1 pointsby PMunch3 yıl önce2 comments

Labelled exceptions for smoother error handling

peterme.net

1 pointsby PMunch3 yıl önce0 comments

NXP has messed up their password form validation

peterme.net

23 pointsby PMunch3 yıl önce33 comments

Is Nim a Transpiler?

peterme.net

44 pointsby PMunch5 yıl önce70 comments

comments

29 gün öncediscuss

Pretty sure it wasn't just some guy who figured "I could totally do that" and was allowed to give it a go. Rather it was probably a scientific study like the current efforts, using the best tools available at the time. In 1969 humanity sent people to the moon, and we can't even unroll some old scrolls? It's hard to know, when you're there, whether technology has gotten good enough to do something or if it isn't.

EDIT: Read some more into this. From Wikipedia and its sources:

> In 1969, Marcello Gigante founded the creation of the International Center for the Study of the Herculaneum Papyri (Centro Internazionale per lo Studio dei Papiri Ercolanesi; CISPE). With the intention of working toward the resumption of the excavation of the Villa of the Papyri, and promoting the renewal of studies of the Herculaneum texts, the institution began a new method of unrolling. Using the 'Oslo' peeling method, the CISPE team separated individual layers of the papyri. One of the scrolls exploded into 300 parts, and another did similarly but to a lesser extent.

> The results were mixed: one of the scrolls literally exploded (into more than 300 bits) during the "peeling" and attempts to put the scraps back together gave little hope for success. The second - PHerc.Paris.2 -, on the other hand, had survived in a slightly less fragmented state.

So this was new science being done on the possibility of unrolling the scrolls and piecing together information from the fragments. Whether the fragments from PHerc. 1667 was decoded I'm not sure. The work has been digitized (and photographed with specific wavelengths of light where the ink is more distinguishable), but I couldn't figure out if it was open to the public anywhere.

Another interesting part: > In 1756, Abbot Piaggio, conserver of ancient manuscripts in the Vatican Library, used a machine he also invented, to unroll the first scroll, which took four years (millimeters per day). The results were then copied (since the writing disappeared: see above), reviewed by Hellenist academics, and then corrected once more, if necessary, by the unrolling/copying team.

So it's not like they never got anything useful out of the scrolls but kept on trying anyways.

2 ay öncediscuss

I believe the Butlerian Jihad caused a ban for "thinking machines" with a tenet of "Thou shalt not make a machine in the likeness of a human mind." This to me at least points at a ban for things that behave or feel like a human, not on the underlying math. An ornithopter probably has some fancy AI-esque flight stabilization, but it isn't expressed in a human way. The same goes for function approximators and surrogate models, no one would do the things we see people doing with AIs today, letting them talk them into heinous acts or fall in love with them.

That being said I can very much recommend the two Hyperion books for a good look at AI and co-dependence in sci-fi.

6 ay öncediscuss

Definitely, I've been trying out a lot of dithering algorithms, and while they have big differences with only black and white as soon as you start adding more shades of grey they all look pretty much exactly the same as the input image. I'd imagine good dithering with colours would look amazing

6 ay öncediscuss

Just had a look at this and here is the result for the test image: https://uploads.peterme.net/test-image_qr.png.

Looks pretty good! It looks a bit like a dither, but with fewer artifacts. Definitely a "sharper" look than blue noise, but in places like the transitions between the text boxes you can definitely see a bit more artifacts (almost looks like the boxes have a staggered edge).

Thanks for bringing this to my attention!

6 ay öncediscuss

Thanks! I would imagine printing on paper would be a completely different ball game. I actually considered scanning the actual epaper display to show each of the dithering techniques in their intended environment as it does change the look quite a bit. From the little I know about typography and things like ink-wells I can definitely see how certain algorithms can change quite significantly. The original post here has a pattern which looks similar to old newspapers, maybe that's worth looking into?

6 ay öncediscuss

Ooh, I haven't actually! I'll need to implement and test this for sure. Looking at the results though it does remind me of a dither (https://pippin.gimp.org/a_dither/), which I guess makes sense since they are created in a broadly similar way.

6 ay öncediscuss

Just did a bit of a deep dive into dithering myself, for my project of creating an epaper laptop. https://peterme.net/building-an-epaper-laptop-dithering.html it compares both error diffusion algorithms as well as Bayer, blue noise, and some more novel approaches. Just in case anyone wants to read a lot more about dithering!

7 ay öncediscuss

Same! I've already signed up for the Time 2 and super stoked for it, then I saw the announcement for the Round 2 and I was about to switch over until I noticed it didn't have a heart rate sensor. I know its sleek and elegant, but that slight bulk would be worth it in my opinion. And who knows, with the extra thickness they might've been able to squeeze in more battery to get it to the 30 days battery life cited for the Time 2.

Also unfortunate that it's missing the RGB backlight of the Time 2. I can think of a few good use cases for it, but if it's only on the Time 2 that means fewer apps would use it.

7 ay öncediscuss

I've been wanting a browser plugin like this for ages. Basically tell it which sites to limit, then once loaded it won't re-load for a certain amount of time, or until the next day (not necessarily 24 hours). This way there is no reason to keep checking the news, they won't change.

8 ay öncediscuss

Indeed, I have a remote doorbell where the outer button is a piezo button and the inside bell part is connected to a socket. But the button is quite thick, presumably because it needs a bit of travel to get enough energy. Granted that's for a device that sends multi-wall penetrating strength of 433Mhz radio waves. For something like this where the distance is only about 25cm you might be able to get a button small enough.

8 ay öncediscuss

Nothing, and it fact this works. To move to an example which actually compiles:

    import math
    
    echo fcNormal
    echo FloatClass.fcNormal
    echo math.fcNormal
    echo math.FloatClass.fcNormal

All of these ways of identifying the `fcNormal` enum value works, with varying levels of specificity.

If instead you do `from math import nil` only the latter two work.

8 ay öncediscuss

There is a direct connection, you just don't have to bother with typing it. Same as type inference, the types are still there, you just don't have to specify them. If you have a collision in name and declaration then the compiler requires you to specify which version you wanted. And with language inspection tools (like LSP or other editor integration) you can easily figure out where something comes from if you need to. Most of the time though I find it fairly obvious when programming in Nim where something comes from, in your example it's trivial to see that the error code comes from the errorcodes module.

Oh, and as someone else pointed out you can also just `from std/errorcodes import nil` and then you _have_ to specify where things come from.

9 ay öncediscuss

Of course, I'm heavily biased, but also very interested in mediating any such issues. I obviously can't, or wouldn't want to, force you to report anything. But it would be very appreciated if you, or anyone else reading this with similar experiences, could report it here: https://docs.google.com/forms/d/1ZWa2GONAM825IxFt8ZOdfn_XeJy...

9 ay öncediscuss

> The community "leaders" / moderation team is also full of abrasive individuals with fragile egos.

I certainly hope this isn't the case any longer. As one of the moderators I feel the current group is very patient and welcoming. At least that's what we're trying for, no one is perfect so I'm certain you can find counter examples. But as a whole I think we're doing pretty well. If you have any specific complaints we would love to hear them. They can be left anonymously in our community feedback form, or you can find we anywhere in the community for a chat.

10 ay öncediscuss

Isn't this better though? The alternative being that every email or phone call is an hour, or that they batch it up based on gut feel. If I get a phone call that could easily steal 6 minutes of focus time (note that I specify focus time, even if the call is only 30 seconds you'd have to mentally switch tasks back and forth).

11 ay öncediscuss

Speech for the disabled would indeed be great, as long as the disability doesn't also affect the system which you use to "silent speak".

As for the privacy thing, I would say that I absolutely hate talking out loud to my devices. Just the idea of talking my ideas into a recorder in my own office where nobody can hear me feels very strange to me. But I love thinking through ideas and writing scripts for speeches or presentations in my mind, or to plan out some code or overall project. A device like this would allow me to do the internal monologue thing, then turn to "silent speak" them into this device to take notes which sounds great. And the form-factor doesn't look that dissimilar to a set a bone-conduction headsets which would be perfect for privacy-aware feedback while allowing you to take in your surroundings.

With this tech demo though it seems like the transmission rate is veeery slow, he sits still in his chair staring into the room and a short sentence is all that appears. Not exactly speed of thought..

And of course there is the cable running off to who knows what kind of computational resources.

The AI parts of this are less exciting to me, but as an input device I'm really on-board with the idea.

11 ay öncediscuss

As other people have pointed out "audio range" is generally 20Hz-20kHz. Your phone (and other audio equipment) is therefore built to be able to transmit those frequencies. The way a speaker creates sound is by passing electricity through a wire, creating a magnetic field, and pushing against a permanent magnet. Either the magnet or the wire is attached to a membrane that will then get pushed out. Doing this between 20-20k times a second and you make sound. However when charged particles (like the electrons in a wire) accelerate they create radio waves, so the magnetic coil in the speaker will also create a small amount of radio waves in the same frequency as the sound it is producing. This is what's called parasitic EMF, and in this case it turns out that this small amount of radio signal is enough to interact with the radio in the wheels.

11 ay öncediscuss

They left their e-mail in the talk, in case you want to increase the odds of reaching them

geçen yıldiscuss

The headline as I read the article was "How I Solved the Century-Old Mystery of a Miraculous Shipwreck Survivor", but it doesn't actually detail _how_ the mystery was solved. They talked to a couple different people, found an old newspaper clipping, but the crucial

> Davidson was picked up by a lifeboat and taken to the Storstad, which survived the collision.

The actual meat of the article, doesn't have any clear source. I guess it might've come from the mentioned piece in "St. Thomas Journal", but it's not exactly clear.

Cool story, but not exactly the "How I solved a mystery" that you'd expect from the headline.

geçen yıldiscuss

Well, the C that Nim outputs isn't exactly human readable. Sure if you know what you're doing you might be able to follow along, but no sane maintainer would admit it into a C project.

It could help the build process a you can pre-compile to C and only use the C build system. And it allows you to run anywhere C can run (we use it for everything from servers to microcontrollers). But apart from that it's mostly an implementation detail.