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This classic article is wrong, BTW, there's no nicer way to put it. It applies the wrong theory. It was already wrong in 1995 when monitors where CRTs, and it's

This classic article is wrong, BTW, there's no nicer way to put it. It applies the wrong theory. It was already wrong in 1995 when monitors where CRTs, and it's way wrong in 2025 in the LCD/OLED era where pixels are truly discrete. Audio samples are point samples (usually). This is nice, because there's a whole theory on how to upsample point samples without loss of information. But more importantly, this theory works because it matches how your playback hardware functions (for both analog and digital reasons that I won't go into). Pixels, however, are actually displayed by the hardware as little physical rectangles. Take a magnifying glass and check. Treating them as points is a bad approximation that can only result in unnecessarily blurry images. I have no idea why this article is quoted so often. Maybe "everybody is doing it wrong" is just a popular article genre. Maybe not everyone is familiar enough with sampling theory to know exactly why it works in audio (to see why those reasons don't apply to graphics).

p0w3n3d 1y ago
I think you're wrong. According to my knowledge the pixels on CRT were rectangular and were throwing their color on neighbouring pixels. Graphics created for CRT were shown nicely on those screens, had much better visuals than displayed on LCD/LED and were antialiases by default (i.e. by the display technology)
- badmintonbaseba 1y ago
  Pixels displayed on CRT displays are not squares, but they are not infinitely small dots either. They are much less well-defined blobs, that even overlap with each other. There is also the complication of composite video signals, where you can't treat pixels as linearly independent components.
  - codeflo 1y ago
    Good PC monitors (especially in 1995) displayed pixels as almost perfect discrete squares. It was home consoles on televisions where people get the idea from that all CRTs were blurry.
    - p0w3n3d 1y ago
      Let me guess: when game creators were thinking about result visuals were they considering that everyone would have this good pc monitor with exact square pixel, or were they taking into account possible distortions that would occur on average CRT? Also: people playing retro nowadays use shaders to emulate CRT https://youtube.com/shorts/W_ZI3w9CYnI https://youtube.com/shorts/W_ZI3w9CYnI
      - codeflo 1y ago
        As I said, >> It was home consoles on televisions where people get the idea from that all CRTs were blurry. The video you linked shows a PS1 game, which proves my point. It's possible you're too young to remember the big difference between a CRT TV and a CRT monitor. Monitors really did show discrete pixels (which was important for tiny text in applications to be readable), while TVs were blurry messes.
justin_ 1y ago
> Audio samples are point samples (usually). This is nice, because there's a whole theory on how to upsample point samples without loss of information. This signal processing applies to images as well. Resampling is used very often for upscaling, for example. Here's an example: https://en.wikipedia.org/wiki/Lanczos_resampling https://en.wikipedia.org/wiki/Lanczos_resampling > It was already wrong in 1995 when monitors where CRTs, and it's way wrong in 2025 in the LCD/OLED era where pixels are truly discrete. I don't think it has anything to do with display technologies though. Imagine this: there is a computer that is dedicated to image processing. It has no display, no CRT, no LCD, nothing. The computer is running a service that is resizing images from 100x100 pixels to 200x200 pixels. Would the programmer of this server be better off thinking in terms of samples or rectangular subdivisions of a display? Alvy Ray Smith, the author of this paper, was coming from the background of developing Renderman for Pixar. In that case, there were render farms doing all sorts of graphics processing before the final image was displayed anywhere.
- jansan 1y ago
  > I don't think it has anything to do with display technologies though. Imagine this: there is a computer that is dedicated to image processing. It has no display, no CRT, no LCD, nothing. The computer is running a service that is resizing images from 100x100 pixels to 200x200 pixels. Would the programmer of this server be better off thinking in terms of samples or rectangular subdivisions of a display? How about a counter example: As part of a vectorization engine you need to trace the outline of all pixels of the same color in a bitmap. What other choice to you have than to think of pixels as squares with four sides?
  - jvanderbot 1y ago
    I really think it would be defined by the set of pixels not of that color that border that color, but maybe I'm thinking about this wrong.
    - thaumasiotes 1y ago
      If your model of the pixels is that they're point samples, they have no edges and there's no way to know what they do or don't border. They're near other pixels, but there could be anything in between.
jvanderbot 1y ago
A pixel is a box that changes color to match the point sample it represents. What's the issue?
- codeflo 1y ago
  To quote my post that you reply to, it's > a bad approximation that can only result in unnecessarily blurry images

p0w3n3d 1y ago

I think you're wrong. According to my knowledge the pixels on CRT were rectangular and were throwing their color on neighbouring pixels. Graphics created for CRT were shown nicely on those screens, had much better visuals than displayed on LCD/LED and were antialiases by default (i.e. by the display technology)

badmintonbaseba 1y ago
Pixels displayed on CRT displays are not squares, but they are not infinitely small dots either. They are much less well-defined blobs, that even overlap with each other. There is also the complication of composite video signals, where you can't treat pixels as linearly independent components.
- codeflo 1y ago
  Good PC monitors (especially in 1995) displayed pixels as almost perfect discrete squares. It was home consoles on televisions where people get the idea from that all CRTs were blurry.
  - p0w3n3d 1y ago
    Let me guess: when game creators were thinking about result visuals were they considering that everyone would have this good pc monitor with exact square pixel, or were they taking into account possible distortions that would occur on average CRT? Also: people playing retro nowadays use shaders to emulate CRT https://youtube.com/shorts/W_ZI3w9CYnI https://youtube.com/shorts/W_ZI3w9CYnI
    - codeflo 1y ago
      As I said, >> It was home consoles on televisions where people get the idea from that all CRTs were blurry. The video you linked shows a PS1 game, which proves my point. It's possible you're too young to remember the big difference between a CRT TV and a CRT monitor. Monitors really did show discrete pixels (which was important for tiny text in applications to be readable), while TVs were blurry messes.

justin_ 1y ago

> Audio samples are point samples (usually). This is nice, because there's a whole theory on how to upsample point samples without loss of information. This signal processing applies to images as well. Resampling is used very often for upscaling, for example. Here's an example: https://en.wikipedia.org/wiki/Lanczos_resampling https://en.wikipedia.org/wiki/Lanczos_resampling > It was already wrong in 1995 when monitors where CRTs, and it's way wrong in 2025 in the LCD/OLED era where pixels are truly discrete. I don't think it has anything to do with display technologies though. Imagine this: there is a computer that is dedicated to image processing. It has no display, no CRT, no LCD, nothing. The computer is running a service that is resizing images from 100x100 pixels to 200x200 pixels. Would the programmer of this server be better off thinking in terms of samples or rectangular subdivisions of a display? Alvy Ray Smith, the author of this paper, was coming from the background of developing Renderman for Pixar. In that case, there were render farms doing all sorts of graphics processing before the final image was displayed anywhere.

jansan 1y ago
> I don't think it has anything to do with display technologies though. Imagine this: there is a computer that is dedicated to image processing. It has no display, no CRT, no LCD, nothing. The computer is running a service that is resizing images from 100x100 pixels to 200x200 pixels. Would the programmer of this server be better off thinking in terms of samples or rectangular subdivisions of a display? How about a counter example: As part of a vectorization engine you need to trace the outline of all pixels of the same color in a bitmap. What other choice to you have than to think of pixels as squares with four sides?
- jvanderbot 1y ago
  I really think it would be defined by the set of pixels not of that color that border that color, but maybe I'm thinking about this wrong.
  - thaumasiotes 1y ago
    If your model of the pixels is that they're point samples, they have no edges and there's no way to know what they do or don't border. They're near other pixels, but there could be anything in between.

jvanderbot 1y ago

A pixel is a box that changes color to match the point sample it represents. What's the issue?

codeflo 1y ago
To quote my post that you reply to, it's > a bad approximation that can only result in unnecessarily blurry images