It is good that this article exists. It explains how to convert screenshot and video capture provided by DOSBox into web-oriented formats, with some welcome considerations about pixel aspect ratio. This is a good basis!

> but in these screenshots we want to retain the crisp and jagged edges that is typical of DOSBox and the old CRT monitors. Therefore we use the -sample option that does not introduce any new colours. Instead it uses nearest-neighbour interpolation (point sampling) to decide the colours of the scaled image.

There are 2 ironic things:

* modern world drifts away from pixel-to-pixel rendering, and indeed the web page presenting the captures constrains it (img in a div in a main with max-width:42em. So, web viewing does introduce some smoothing

* the CRTs-based screens of the days were not that crisp! Especially the color ones, they had a "shadow mask", a grid of RGB spots which had no reason to be aligned with the pixel locations (this is explained e.g. on "How Analog Color TV Works: The Beginnings" by "Technology Connections" https://www.youtube.com/watch?v=dX649lnKAU0 or jump straight to https://youtu.be/dX649lnKAU0?t=576 for explanations and https://youtu.be/dX649lnKAU0?t=665 for close-to-screen example )

> The screenshots obtained in this manner have an aspect ratio of 8:5 which makes the output look stretched horizontally.

Because modern format and/or modern displaying program tend to assume square pixels, which originals were not. Same issue on Amiga (pixel aspect ratio was even different on North-American Amigas and European Amigas) and many others, until VGA then LCD with digital links became established. Consider older CGA/EGA PCs. You mechanically can't fit 640x350 640x400 640x480 640x512 pixels on the same 4:3 area and still get square pixels in all cases. Some machines had border, which somehow can help, but in a number of cases, e.g. the Amstrad CPC, users didn't notice much but the pixels were still not squares!

> The old CRT computer monitors for which these old DOS programs were written had an aspect ratio of 4:3 instead. This stretched look can be fixed by resizing the images to an aspect ratio of 4:3.

The intention is right. Some people don't even notice extremely wrong aspect ratio, the author and I do.

Still, I agree the PNGs of this article are good as "pristine capture format".

The job that the author does to restore aspect ratio is based on repeating the lines and columns. This causes another effect: even programs (e.g. web browser showing that page) that try to do decent job of interpolating will blur some lines and not others, which IMHO adds an unpleasant effect reminiscent of what some LCD screen do when upscaling: they display some positions as is and blur some others.

I consider aspect ratio to be important along with uniform (fair) treatment when adjusting size to modern displays. I'm okay with sacrificing a crispness that does only mathematically existed anyway. You are allowed disagree with me.

As a conclusion, surprisingly enough, I would keep the 1:1 PNG as pristine capture format, and post upscaled versions with interpolation to get correct aspect ratio and fair rendering a bit like CRT did.