fig3

Figure 3. Software-based needle localization methods can be categorized into three: (A) classical image processing methods that use a handcrafted feature extractor and decoder; (B) machine learning-based methods with a trainable decoder; (C and D) and deep learning-based methods with a trainable feature extractor and decoder. Generally, software-based methods take as input either single ultrasound images or a video stream of ultrasound images.