A Reflection Is a View From Underneath, Not a Flipped Copy

How it works

The photograph is scaled to about one and a fifth megapixels and repainted at a low denoise, the lowest of the three compositing pages here, because the subject and the scene should survive nearly intact and only the surface below changes.

The instruction describes the reflection as a second view rather than as an effect: it begins exactly at the contact point, shows the subject from below rather than a copy of the front view, fades as it moves away from the contact line, and is blurred in proportion to the roughness of the surface.

The negative prompt leads with the mirrored copy of the front view, because that is what the category defaults to, followed by the other tells — a reflection detached from the contact point, one sharper than the surface allows, one that does not fade.

The geometry, briefly

A reflection is not an effect applied to an image. It is what you would photograph from a second camera position, and that position is completely determined: take your real camera, mirror it through the plane of the surface, and look up from there.

That single fact produces every rule people usually learn as a list.

You see undersides, because the mirrored camera is below the plane looking up.

The reflection is compressed vertically when the real camera is high, because the mirrored camera is looking up steeply, and extended when the real camera is near the surface.

Vertical lines stay vertical and horizontal ones converge differently, because it is a real perspective view rather than a transformation of a picture.

And the reflection touches the object exactly at the plane. There is never a gap, and a gap is the fastest way to spot a pasted one.

Fade and blur are two different things

These get conflated, and separating them explains why some fakes look plastic.

The fade is about how much light comes back. Surfaces reflect strongly at grazing angles and weakly when viewed head-on, so the part of the reflection nearest the contact line — seen at a very shallow angle — is the brightest, and it falls away with distance. This is why a reflection is never uniform, even on perfect glass.

The blur is about surface roughness. A polished stone returns a near-perfect image; a brushed or satin surface scatters each ray slightly, so the reflection softens with distance because scattered rays have farther to spread. A surface that visibly has texture cannot return a sharp reflection, whatever the fade looks like.

Get the fade right and the blur wrong and you have a glass table with a matte reflection, or a laminate worktop acting like a mirror. Both read as wrong immediately and neither is easy to articulate.

What the photograph does not contain

The honest limit is the same one that governs the multi-angle page, arrived at from a different direction.

A reflection shows the underside, and if your camera never saw the underside, that part of the image is inferred. For a smooth bottle this is nearly free, since the base is a continuation of a form that is fully described. For a shoe, a device with ports, or anything with printing on the bottom, it is invention with a convincing finish.

Which sets the usable boundary. As a hero treatment, a display image, or a banner, the reflection is decoration and nothing is being claimed. As part of a product gallery, an invented sole or base is a statement about the product that the photograph does not support.

Publication gate

This page ships once the workflow has been run against an upright bottle on polished stone, a shoe photographed from above, an object on a satin surface, and a subject whose contact line is cropped out of frame, with the first centimeter below contact inspected for gaps and the reflection's sharpness compared against the visible roughness of the surface in every case.