Comment by maxbond | Hacker News Reader

Comment by maxbond | Hacker News Reader

Parent Full thread

Pixels are a unit of area like an acre or square meter (see [1] if skeptical). So a line of pixels is still 2D, in the same way a 1x5 unit rectangle is a 2D object with an area of 5 units squared. I'm not sure there's an accepted name for a 1 dimensional picture element. Maybe lenxel, working backwards from length like voxels works backwards from volume?

I like the sibling's suggestion about audio; if we were to adopt it, it would make a 1D element a "sample".

[1] People are often confused on this point, because in the course of everyday conversation we don't distinguish between the number of pixels on the side of a rectangle (which is a 1D quantity) and the number of pixels inside that rectangle (a 2D quantity). So if I say I have a 10 pixel by 10 pixel image, what I mean is that I have a grid with an area of 100 pixels, with sides measuring 10 pixel-widths by 10 pixel-heights (each a 1D quantity of length). If that looks awkward and tiresomely pedantic to you, well, that's why we just say pixels and let the details be implied.

If you're still skeptical, consider for instance that voxels are more clearly a unit of volume (think Minecraft blocks), and that pixels are obtained by subdividing a rectangle. Another useful way to think about it might be by replacing "pixels" with "dominos" and imagining making grids out of dominos, pixels can be tricky since you can't see their area yourself.

Still, fixed size pixels arranged in a line, where each pixel's position is described by a single coordinate, could be called a 1-dimensional arrangement of pixels. You could do the same with voxels, or corn fields of 1 ha each, or hypercubes.

Yeah, if you have an array of pixels or hypercubes, you can think of it as a 1D array and leave the details of what's contained below your barrier of abstraction. And that's a useful mental model much of the time.

But I would still argue that an array of pixels doesn't represent a 1D image. If a 2D image associates areas with color or intensity values, a 1D image would associate intervals with color or intensity values (since intervals are the measure of 1D space which is analogous to areas in 2D space). In my mind, those are different data structures, but the difference is pretty nuanced and I would understand if people felt I was splitting hairs.

Given the question, "what's a 1D image?" I'd argue this is the more complete answer. But if we were to ask that question in the context of a real world problem, yours is likely to be the more useful answer.

> Pixels are a unit of area like an acre or square meter.

Some computer graphics experts don't agree with this: http://alvyray.com/Memos/CG/Microsoft/6_pixel.pdf

I've skimmed the article, it's gunnuh take me a while to read it so that I can respond properly. In case I don't get around to it, thanks for the article. It's an interesting perspective.

“1D image” is the technical term used in graphics programming for a single row buffer of width * bytes per pixel.

Am I so out of touch? No, it's the children who are wrong!

But in all seriousness, call it what you want, I happen to enjoy this minutia but understand many people see it as an impediment to clear communication. If you're working in the unusual contexts where the difference matters you probably know.

Reply on news.ycombinator.com