There are several common types of image annotation techniques used in machine learning, including: 1. Bounding Box Annotation: Drawing rectangles around objects of interest. 2. Polygon Annotation: Drawing irregular shapes or outlines around objects. 3. Semantic Segmentation: Labeling individual pixels or regions with corresponding object classes. 4. Landmark Annotation: Identifying specific points or landmarks on objects. 5. 3D Cuboid Annotation: Annotating objects in 3D space using cuboid-shaped volumes. The choice of annotation technique depends on the specific requirements of the machine learning task and the level of detail needed for object detection or identification.