There are two different uses of the word ‘see’. You can see an object, a picture or a drawing for instance, where you see what is in front of you, as a blueprint. But you can also see a likeness in someone’s face. There’s a categorial difference between the two objects of sight.
Other examples of this seeing-as are seeing a geometrical drawing as a glass cube, seeing a triangle as a mountain, wedge or arrow, or the well known rabbit-duck drawing, in which you can recognize a rabbit as well as a duck.
The Austrian-British philosopher Ludwig Wittgenstein calls this experience ‘noticing an aspect’, or aspect perception (Aspektenwechsel): you see that the object you are looking at has not changed, and yet you see it differently.
Aspect perception is an unstable state. Only in the change of aspect does one become conscious of the aspect. In general, it involves noticing a similarity. You can say that you experience a comparison, an object is seen as a variation, or derivation, or copy, of another one.
When you see a tree, for example, and realize that it is a tree, you see its resemblance with other trees. Seeing is comparing, seeing is interpreting. Everything we perceive, we perceive in its relevant aspects: in a picture we immediately see what it represents and respond to it accordingly.
When a child plays with a box and cries out that it is a house, the box immediately becomes a house. To see this aspect means to see something that cannot be shown.
Seeing an aspect means recognizing an aspect that you hadn’t seen like that before. The picture doesn’t change, and our seeing doesn’t change either. It’s our interpretation that changes. This raises the question whether a picture is seen or thought of.