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I don't understand how my monitor works.

I am at 1920x1080 resolution which I thought was the native resolution of my monitor. I proceed to take a screenshot, then I open it up in a image program at 100% zoom (aseprite), which should mean that 1 pixel of the screen is 1 pixel of the image. The screenshot looks TWICE as big as my monitor.

How is this possible? Is my monitor downscaling the resolution to half so that it's not actually 1920x1080? I am questioning this because I could see some artifacts on the rendering of images that are supposed to be pixel perfect but look asymmetrical on my screen, though when I take a screenshot and zoom in they look perfect.

Here's an example: Photo of my monitor taken with phone

The 2 vertical side black lines of the arrow are clearly taking 3 physical pixels on the left and 4 physical pixels on the right.

When I take a screenshot of that exact image I get this:

Screenshot

Opening the screenshot up in an image software shows clearly how the 2 black lines are the exact same width in pixels.

How can a screenshot be different than what I see on my monitor, given that I should be using the native resolution of my monitor?

Is there some hidden upscaling/downscaling for some monitors that cause them to not be at their claimed native resolution?

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  • $\begingroup$ Which operating system are you using? And how did you do the screenshot? $\endgroup$
    – Thomas
    Jan 6, 2023 at 14:17
  • $\begingroup$ I'm on windows and it's just print screen. I think I have the answer now, incredibly this is related to how R G and B led are laid out (in that order) on the monitor, which breaks the square geometry of pixels for certain combination of colours. I think it's extremely interesting so I'll probably post my own answer to this XD $\endgroup$
    – Lake
    Jan 6, 2023 at 14:19

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This is related to how pixel LEDs are laid out on an LCD monitor.

Pixel LEDs

As shown in the image, for an LCD display, the RGB LEDs are arranged in that order, each one of them taking approximately 1/3 the width of a pixel.

This means that for the left black line of my red arrow, we will have this sequence of LEDs (x=off):

xxB xxx xxx xxx xxx Rxx .....

While for the thick line on the right, they will be like:

Rxx xxx xxx xxx xxx xxB

This changes the visual width of the line to be 4/3 of a pixel wider for the right line (4 more x in between coloured LEDs!).

So incredibly, the colour layout of an image can change its visual geometry due to how pixel colours are created.

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