#downsampling

If you downsample a video game it means you’re rendering the image at a larger resolution than your monitor’s native resolution and shrinking it back down so it fits on the screen. 

So, for example, if you have a 1920x1080 monitor, you could downsample by forcing your graphics card driver to render the game at, say, 2560x1440 and shrink it back down to 1920x1080 so you can see the whole image. What it’s doing when it renders at 1440p is utilising more pixels than can normally be displayed by your monitor. That means more information is able to be rendered, rather than some information having to be interpolated. When viewed at your regular monitor size, this results in a cleaner, sharper image. Downsampling is an excellent form of anti-aliasing as a result.

The big drawback to this is that a lot more power needs to go into rendering all those extra pixels, even if the image is resized (downsampled) to fit on your monitor. Therefore, you need a pretty hefty PC to be able to play while downsampling, particularly if you want to go to 4k and beyond. With more demanding games this can be difficult to do, even with good GPUs.

Hotsampling is particularly useful for people who take screenshots but who aren’t necessarily that bothered about playing the game while downsampling. For these people, graphical fidelity is most important for the end shot, rather than during the experience of playing. 

Hotsampling lets you play at your native resolution (so, in our example, 1920x1080), but when you’re ready to take a screenshot you can momentarily render the image at a much higher resolution (so 2560x1440, or 3840x2160, etc). While it’s at this larger size it won’t fit on your monitor, so you’ll only be able to see some of the image. Once you’ve taken the screenshot, you can change the resolution back to native again. The screenshot will show the full image -- even the parts that didn’t fit on your screen -- and it will be at that larger size, so then when it’s displayed on a smaller screen it is downsampled - either automatically by a browser or manually if you choose to resize it in an image editor. 

The end result of both is the same: you get a screenshot that is larger than your native monitor resolution which, when resized in some way or another and viewed on your monitor, gives you better image quality. The benefit of hotsampling is that you can continue to play the game without constantly taxing your computer, and can theoretically as a result push the resolution of the screenshots further than you would otherwise be able to do.

There are various tools available that let you hotsample, but not all games are compatible. Downsampling, however, is relatively easy to do in many games now, thanks to technology like nvidia’s DSR (dynamic super resolution).