Where features tend to include:
- Points -
- Blobs - smooth areas that won't (necessarily) be detected by point detection. Their approximate centers may also be considered interest points
- Edges -
- a relatively one-dimensional feature, though with a direction
- Corners - Detects things like intersections and ends of sharp lines
- a relatively two-dimensional kind of feature
In comparisons between similar images, one should keep in mind that blob-centers can become interest points, gradients can become edges, etc., and that the difference to detectors can be and/or should be fuzzy.
- Interest point - could be said to group the above and more
- preferably has a clear definition
- has a well-defined position
- preferably quite reproducible, that is, stable under relatively minor image alterations such as scale, rotation, translation, brightness.
- useful in their direct image context - endpoints, corners, intersections
- Region of interest
Detecting anything more complex than a point, edge, blob, or corner. Regularly by example.