One of the walls in my house is decorated with pop-up flowers. The wall is quite a dark grey, and the flowers are white. Eerily, I've noticed that if I stare at one of the flowers, I get the impression that the surrounding flowers appear to turn.
This illusion reminded me of some others that I'd seen on the internet of moving circles, like the one below.
Seeing the moving circles? Unsettling, isn't it.. And of course, there's the one that went viral about the dress, is it blue/black or white/gold?
Of course, we know when we look at these that the circles aren't actually moving, and if I drop the dress image into Lightroom I can quickly check the colours to get an accurate answer. But this does show how much of what we see is actually in our heads and not a reality. We aren't computers that logically record what we see. The world we live in is complex, and so our brain takes shortcuts and second guesses, often making mistakes or giving different results compared to others.
This is something that I'm beginning to notice a lot more in photography. The colour of light changes dramatically and can swing from very red to very blue depending on the time of day and cloud cover. But our brain is very good at balancing this out, so we don't notice that light is often blue on cloudy mornings, or how orange the lights in our house can be at night time.
This also applies to the tone of an image (the light and dark areas). We often assume that the sky in an image is bright, and that areas in shadow must be dark. But often this isn't the case, an under exposed image will move the sky towards the midtones, but we may not notice because we just assume that the sky must be bright.
In my original image of snow in Iceland, I assumed that the image was quite bright, but after re-evaluating it and a quick re-edit, you can see that it's actually much darker than it should have been.
I've now become trained and regularly checking my histogram in Lightroom/Photoshop. Running your pointer over different areas of the image will also show you the RGB values and give you a more accurate display of the tones in your image.
This is worth doing on a regular basis so you can start to train yourself to see your work objectively and not be fooled by our brains, which is where the illusion really lies!