Visual Features

Where

Position

Position of an object within the two-dimensional space of the retina, augmented with depth information from stereoscopy. (the comparison of the images received from the 2 eyes). The absolute position of something in visual space and the relative position of multiple objects in that space.

Motion

The changes in position of an object or group across time in absolute terms and in relation to others.

What

Colour

the mix of colour-related parameters (red vs green and blue vs yellow ) derived initial from the cones in the retina.

Brightness

the relative light intensity

Shape

Predominantly related to the spatial character of the outline of an object

Texture

spatial patterns of brightness and colour

Orientation

the spatial orientation of a shape (horizontal, vertical, angled, tilted toward or away)

Size

relative size of an object

Surface Curvature

The 3-dimensional contours of the surface of an object

Other Hybrid features

Transparency

the simultaneous visibility of multiple objects at the same 2 dimensional location in the image field

Shadow

sections of lower brightness interpreted as shadows cast by objects.

Figure / Ground

Perception organizes visual input into figures standing out against a background.

Depth of Field

This is not really a perceptual feature, but rather a useful attribute of vision. As the eye focussed on objects at a certain depth, things at other depths fall out of focus, providing a fovea-like effect in the depth dimension.

The visual cortex has extra sensitivity to specific combinations of these features. For example, the human vision system devotes a lot of resources to the recognition of faces which depends on a number of these feature in precise combination.