An object produced or shaped by human craft, especially a tool, weapon, or ornament of archaeological or historical interest.
Something viewed as a product of human conception or agency rather than an inherent element: “The very act of looking at a naked model was an artifact of male supremacy” (Philip Weiss).
A structure or feature not normally present but visible as a result of an external agent or action, such as one seen in a microscopic specimen after fixation, or in an image produced by radiology or electrocardiography.
An inaccurate observation, effect, or result, especially one resulting from the technology used in scientific investigation or from experimental error: The apparent pattern in the data was an artifact of the collection method.
Looking at each image, some are "covered" by vegetation.
that's a transparency issue, i think:
The difference in coloration seems to be due to the underlying photo.
they do seem to be distorting the light reflected by the subject matter (or the image thereof). this would be consistent, really, with either something between the ground and the lens, or a post-production artifact.
I think these must be left over from some sort of place holders that were in place before the pictures were put into the grid.
i'm still going with water-droplets in the transparent housing. some are stretched out of circular shapes, which suggests they were there BEFORE processing.