So, now that I have a choice...

I am a fan of a free program called nircmd (nirsoft.net), which is the compact command-line utility that I use as part of my save-selected-screen-region-in-a-file macro under AutoHotKey.

The story so far is this: Up until yesterday, I used nircmd to save screen clips as PNG files, but when I couldn't get my Windows version of emacs to display such files, I modified my macro to save screen clips as JPG files. Then I figured out how to get emacs to display PNGs, so now I can save either type of file.

The question arises: is one format better than the other?

Asking if something is better than something else requires one to ask, "Better in what way?"

Is one image is more legible than the other?

Based on my informal eyeballing of a PNG and JPG of the same image, they are equally legible.

Is one kind of file consistently smaller than the other? Here, I ran into some interesting data.

If I clip a region of my screen that is completely white or completely black, both formats result in small files that weigh in at tens of kilobytes in size.

If I clip a region of my screen that contains a multicolored graphic image, the JPG format results in a file that is consistently much smaller (15% or less) than that of the PNG equivalent.

If I clip a region of text on my screen, the PNG file is consistently much smaller, but both types of files are small to begin with (the JPG version will be "high" tens of kilobytes in size).

Conclusion: if size is the criterion for "better," then I'd be better off saving all of my screen clips in JPG format.

And now, back to work...