fig3
![Advancements in needle visualization enhancement and localization methods in ultrasound: a literature review](https://image.oaes.cc/79a69f4a-333a-43e6-b302-f191c95e0ebf/ais4020.fig.3.jpg)
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.