Why do my screenshots look too dark on other PCs?

Thanks Sswift, the altered image you posted looks the way I intended it to look on mine. It is only marginally brighter than the one I posted at the top of the page.

I haven't used any calibration programs yet fortunately, so I'll try what you suggest.

- I just tried what you said (Contrast 100, Brightness on monitor set such that a 1,1,1 grey square is barely visible on black background) - and now it seems to be correct. My original image is now too dark (which is a good thing) and your altered image looks as it should (very similar to my original image).

I guess I'll have to render things again now.

Thanks,
Matt