On this site we often have images of schematics or PCBs etc. that are relatively high in resolution. Using the standard way of embedding an image in the post reduces the image size to something that fits the posting format; but it doesn't rescale the image, it just sets the image tag so that the browser does the rescaling (to 660px or similar).
Even from long time users I often see comments that the image is in an unreadable resolution when all they need to do is to right click and chose "open image in new tab/window". This is not only inconvenient, it is also that many people forget that it is possible, and in the case the image is already in a scaled down resolution, it is wasted time.
I therefore propose that we add the feature to the image upload process that when the image would be scaled down by the img html tags values, it will automatically get a link to the higher resolution version. If it is smaller, then such a link is not necessary, and by the existence of the link we can see that there is (or is not) a higher resolution version available.
For visualizing things (and to have a possible solution markup available that people can use themselves manually), this is how it would currently be (random image from google image search):
And this is how it should be: