OK, so what constitutes a low-key shot? I have analyzed some of the images in the exhibition gallery, in hope of getting wiser on the matter. In my opinion A-C and E above are no doubt low-key, D I would say is too, F and G are dubious and H is not low-key in my opinion. Now look at the histograms of the images. What are the common traits of the low-key ones? 1. No white to the left, in fact they all peak at the far left, in other words the shadows are clipped and totally black. 2. The median is low, picture D having the highest median of 16. What does this mean? Median is a statistical term, similar to mean or average, but more correct to use when the distribution (of tones in this case) is 'uneven'. The distribution of tones _is_ uneven in low-key shots, with the main weight of the tones in the shadows (left on the histogram). The histogram (the distribution of tones) in F looks similar to the low-key ones, but the median is almost twice as high as in D, the least certain low-key shot of the ones I consider low-key. Looking at the image, the lower half is low-key, even if the highest highlights reside here, while the upper half does not seem to be. I'd say too big of an area of the picture is in the midtones and highlights. This is reflected in the higher median. Image G does not clip the shadows enough - we see some white to the left of the shadow peak in the histogram. Also, there are quite a bit of midtones in the shot, which is reflected by the relatively high median of 31. The shadows of H peak even further up the greyscale and hardly has any totally black pixels. The midtones don't seem too many, so perhaps this image could be made into a low-key shot with some simple levels adjustment? Conclusion: If you want to be sure your image is a low-key shot, study its histogram. Make sure that shadows peak in black and look at the median, which should be very low, perhaps below 20 or perhaps even lower. Note: Everything above was written at an early stage of the challenge, at the same point in time as the composite image above was first posted. Since then, I've had to expand my view on when a photograph could be said to be low key. In fact I'd say all the images above are more or less low key shots. Please read the comments below for further details.