Final answer:
Foreshortening and elongation are both types of shape distortions, altering the perceived dimensions of an object in an image. Magnification, however, is not a distortion but refers to the size relation between the image and the object, with a positive magnification less than 1 indicating an upright, smaller image.
Step-by-step explanation:
Among the options provided, foreshortening and elongation are considered a part of shape distortion. Both of these terms refer to types of distortions that can affect the appearance of an object in an image.
Foreshortening is a technique used to create perspective in an image by exaggerating the parts of an object that are closer to the viewer, which makes them appear shorter than they actually are. Elongation, on the other hand, is a distortion where the object appears stretched out along the axis parallel to the direction of projection or viewing.
Magnification, meanwhile, refers to the ratio of the image's height to the object's height. It is not a type of shape distortion, but rather a measure of how much larger or smaller the image is compared to the object itself. Positive magnification less than 1, as mentioned in the provided information, indicates the image is upright but smaller than the object, such as when viewing through a diverging or concave lens.