Question

I have looked at sources on optics and vision science which use the expressions "real optical image," "optical image" or "retinal image" for the image which the optical system of the human eye projects onto the retina, and which either state or infer (by way of illustrations, pictures of optical images in pinhole cameras or eyes) that this image is a picture, a visual representation of the scene in front of the eye.

But surely an optical image as projected by a lens or lens system (or by a pinhole) is not, in itself, a picture, but a certain kind of two-dimensional distribution of visible EMR flowing through a plane in space, i.e. one in which the light energy at each point is coming from a single object point in 3D space lying in a single direction from the lens or pinhole, and which may or may not be projected onto a surface and reflected from it, and which may or may not then be reflected to the eyes of an observer.

Since the human eye evolved to form such as "image" of a scene on the retina, and since this distribution of visible EMR is interpreted by the brain as the kind of distribution that it usually is (as defined above in my non-scientific way), when an observer looks at a surface that is reflecting one, and it’s re-projected onto the retina, then the brain interprets it in the same way, and the observer sees 3D objects. Then and only then does a picture come into being. That’s when picture perception take place, and only in the mind of the observer.

There is no little observer in the eye looking at the optical image on the retina, which in any case is being absorbed by the photoreceptor layer, not reflected from it.

Surely such optical images must have been formed perfectly well by small holes (as in pinhole images of the Sun under a tree) or (not so well) by translucent bits of rock (or water drops?) long before there was any such thing as a visual perceiver.

On a sunny day I can look out my bedroom window and see a sunny scene outside, or I can use a magnifying glass as a lens to project an inverted optical image of the scene onto the opposite wall.

As long as the lens is in place, each point on a small area of wall is receiving visible EMR from a single point in the scene (there’s an optical image there), and each point on the wall and is reflecting that EMR diffusely. When I look at that area of wall, the optical system of my eye focusses the EMR from each point on the wall to a single point on my retina, forming what my brain interprets as the optical image of a 3D scene, not an area of wall, and I see a picture of the scene.

In short (!), am I right in thinking that, without a visual perceiver, there may be "images" of objects in the sense of optical images (those patterns of EMR, projected on a wall, on the ground, or on a retina), but there is no such thing as an "image" in the sense of a visual representation or picture of objects?
A) The optical image is a direct visual representation, resembling a picture of the scene observed.
B) An optical image is a representation solely characterized by the distribution of visible electromagnetic radiation (EMR) without intrinsic pictorial qualities.
C) The optical image on the retina is perceived as a picture only when observed by a visual perceiver; otherwise, it remains an abstract distribution of EMR.
D) Optical images, regardless of whether observed or not, inherently represent visual scenes as perceived by a visual perceiver.

Answer 1

A real image is a pattern of EMR which can be projected and formed by converging light rays from an object's points. This pattern does not possess pictorial qualities until it is perceived by an observer, where the brain synthesizes it into an image with perceived depth and form.

Step-by-step explanation:

The concept you're discussing relates to the nature of optical images and how they are perceived. A real image is an arrangement of light rays that originate from distinct points in the real world and converge to form coherent visual information, capable of being projected onto a surface, such as film in a camera or the retina in the human eye.

This optical image is, fundamentally, a two-dimensional distribution of visible electromagnetic radiation (EMR), which doesn't intrinsically hold any pictorial value until it is perceived by a visual observer. The process of perceiving a real image involves the conversion of this EMR distribution into electrical signals by the retina, which are then interpreted by the brain to construct the perception of a three-dimensional scene.

Without a perceiver, what exists is simply the pattern of EMR that has the potential to be interpreted as a visual scene, but it is not an 'image' in the sense of a visual representation or picture itself. Therefore, the correct understanding would be articulated by option C: The optical image on the retina is perceived as a picture only when observed by a visual perceiver; otherwise, it remains an abstract distribution of EMR.