Semiotician Roland Barthes writes in Camera Lucida about punctum and its opposite studium, as two different ways of experiencing images. He describes punctum as something in the image that 'pierces the viewer' and shoots arrows through the flat image.
It is often about a small detail which catches your interest and sticks in your memory, long after the picture in question is out of sight. Punctum is not part of the image, but in the viewer's mind and beyond the photographer's control. It can be difficult to point to the punctum of the image.
Once again: It can be difficult to point to the punctum of the image.
In retrospect the concept becomes clear and grows in strength. It could be a detail that captivates the viewer and strengthens the image, or acts in the opposite direction, as disturbance, error or deviation. The point that punctures the retina – to be read in Braille. The dots’ shape form a light dark shadow. If every library had a copy of Camera Lucida in Braille, could your fingers resist touching the dots?