A blob is a region that we can discern based on color. Perhaps the blob itself has a distinctive color, or perhaps the background does. Unlike the term "object", the term "blob" does not necessarily imply something with mass and volume. For example, surface variations such as stains can be blobs, even though they have negligible mass and volume. Optical effects can also be blobs. For example, a lens's aperture can produce bokeh balls or out-of-focus highlights that can make lights or shiny things appear strangely large and strangely similar to the aperture's shape. However, in BeanCounter, we tend to assume that a blob is a classifiable object.
Note
The term "bokeh" comes from a Japanese word for bamboo. Different authors give different stories about the etymology, but perhaps someone thought bokeh balls resemble the bright rim of a chopped piece of bamboo.
Typically, a blob detector needs to solve the following sequence of problems:
Segmentation: Distinguish between...