Ok, but that’s not what an digital image is. Images are designed to be invariant across camera capture and display hardware. The panel driver should interpret the dsp representation into an appropriate electronic pixel output.
Truth is, a pixel is both a sample and a transducer. And in transduction, a pixel is both an integrator and an emitter.
> If you are looking to understand how your operating system will display images, or how your graphics drivers work, or how photoshop will edit them, or what digital cameras aim to produce, then it’s the point sample definition.
They also look more like a square when I back away. And the mismatch of the square model doesn't mean the point model is good.
So your intuition for why squares makes sense is wrong, but you’re still holding on to it.
> doesn't mean the point model is good.
What does show it’s a good model is all the theory of image processing and the implementation of this theory in camera display systems.
You’re welcome to propose an alternative theory, and if that is consistent, try to get manufacturers to adopt it.
I said subpixels are rectangles. Because they are.
If the point model was all you need, then objects small enough to slip between points would be invisible. Which is not the case.
In particular a shot of the night sky would look pure black.
So if being wrong means we should abandon the model, then we can't use squares or points.
https://upload.wikimedia.org/wikipedia/commons/4/4d/Pixel_ge...
I look forward to your paper about a superior digital image representation.
Or are you arguing that the slightly rounded corners on the rectangles make a significant difference in how the filtering math works out? It doesn't. On a scale between "gaussian" and "perfect rectangles", the filtering for this shape is 95% toward the latter.
Even some VGA modes have non-square pixels, and these were used by many games and... Windows 9x splash screen.
They are just bits in a computer. But there is a correct way of to interpret them in a particular context. For example 32 bits can be meaningless - or it can have an interpretation as a twos complement integer which is well defined.
If you are looking to understand how an operating system will display images, or how graphics drivers work, or how photoshop will edit them, or what digital cameras produce, then it’s the point sample definition.
And for pixel art, the intent is usually far from points on a smooth color territory.
Multiple interpretations matter within different contexts inside the computer context.
They use a physical process to attempt to determine light at a single point. That’s their model they try to approximate.
> And for pixel art, the intent is usually far from points on a smooth color territory.
And notice that to display pixel art you need to tell it to interpret the image data differently.
Also it has a vastly different appearance on a CRT where it was designed which is less like a rectangle.
According to who?
A naked camera sensor with lens sure doesn't do that, it collects squares of light, usually in a mosaic of different colors. Any point approximation would have to be in software.
> Any point approximation would have to be in software.
Circuits can process signals too.
And outputs what? Just because the input is an area does not mean the output is an area.
What it if it outputs the peak of the distribution across the area?
> that are pretty square.
If we look at a camera sensor and do not see a uniform grid of packed area elements would that convince you?
I notice you haven’t shared any criticism of the point model - widely understood by the field.
> What it if it outputs the peak of the distribution across the area?
It outputs a voltage proportional to the (filtered) photon count across the entire area.
> If we look at a camera sensor and do not see a uniform grid of packed area elements would that convince you?
Non-uniformity won't convince me points are a better fit, but if the median camera doesn't use a grid I'll be interested in what you have to show.
> I notice you haven’t shared any criticism of the point model - widely understood by the field.
This whole comment line is a criticism of the input being modeled as points, and my criticism of the output is implied by my pixel art comment above (because point-like upscaling causes a giant blur) and also exists in other comments like this one: https://news.ycombinator.com/item?id=43777957
This is not true. And it’s even debunked in the original article.
No, it's not. That article does not mention digital cameras anywhere. It briefly says that scanners give a gaussian, and I don't want to do enough research to see how accurate that is, but that's the only input device that gets detailed.
It also gives the impression that computer rendering uses boxes, when usually it's the opposite and rendering uses points.
In signal processing you have a finite number of samples of an infinitely precise contiguous signal, but in image processing you have a discrete representation mapped to a discrete output. It's contiguous only when you choose to model it that way. Discrete → contiguous → discrete conversion is a useful tool in some cases, but it's not the whole story.
There are images designed for very specific hardware, like sprites for CRT monitors, or font glyphs rendered for LCD subpixels. More generally, nearly all bitmap graphics assumes that pixel alignment is meaningful (and that has been true even in the CRT era before the pixel grid could be aligned with the display's subpixels). Boxes and line widths, especially in GUIs, tend to be designed for integer multiples of pixels. Fonts have/had hinting for aligning to the pixel grid.
Lack of grid alignment, an equivalent of a phase shift that wouldn't matter in pure signal processing, is visually quite noticeable at resolutions where the hardware pixels are little squares to the naked eye.
Since the pixels never were a waveform, never were sampled from such signal (even light in camera sensors isn't sampled along these axis), and don't get displayed as a 2D waveform, the pixels-as-points model from the article at the top of this thread is just an arbitrary abstract model, but it's not an accurate representation of what pixels are.