# heads

Python API: `luxonis_train.nodes.heads`

Heads that turn features into predictions.

Each head sets a task in its `task` class attribute. The task decides which losses, metrics, and visualizers can attach to the
head. The `parser` class attribute names the parser that reads the outputs of the head in the exported model. A head without an
export parser keeps the empty default `""`.

The heads, grouped by task:

 * Classification:
   [ClassificationHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/classification_head.md)
   and
   [TransformerClassificationHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/transformer_classification_head.md).
 * Segmentation:
   [SegmentationHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/segmentation_head.md),
   [BiSeNetHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/bisenet_head.md),
   [DDRNetSegmentationHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/ddrnet_segmentation_head.md),
   and
   [TransformerSegmentationHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/transformer_segmentation_head.md).
 * Bounding boxes:
   [EfficientBBoxHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/efficient_bbox_head.md)
   and
   [PrecisionBBoxHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/precision_bbox_head.md).
 * Instance keypoints:
   [EfficientKeypointBBoxHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/efficient_keypoint_bbox_head.md).
 * Instance segmentation:
   [PrecisionSegmentBBoxHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/precision_seg_bbox_head.md).
 * FOMO object centers:
   [FOMOHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/fomo_head.md).
 * Anomaly detection:
   [DiscSubNetHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/discsubnet_head/discsubnet_head.md).
 * OCR:
   [OCRCTCHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/ocr_ctc_head.md).
 * Embeddings:
   [GhostFaceNetHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/ghostfacenet_head.md).

The bounding box, instance keypoint, and instance segmentation heads derive from
[BaseDetectionHead](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/base_detection_head.md).
They run non-maximum suppression (NMS) only in evaluation mode. Training mode and export mode skip NMS. The metrics run in
evaluation mode. Thus `conf_thres`, `iou_thres`, and `max_det` change what a metric sees. The NN Archive stores the same three
values for the export parser.

## Child Pages

 * [discsubnet_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/discsubnet_head.md)
 * [base_detection_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/base_detection_head.md)
 * [base_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/base_head.md)
 * [bisenet_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/bisenet_head.md)
 * [classification_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/classification_head.md)
 * [ddrnet_segmentation_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/ddrnet_segmentation_head.md)
 * [efficient_bbox_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/efficient_bbox_head.md)
 * [efficient_keypoint_bbox_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/efficient_keypoint_bbox_head.md)
 * [fomo_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/fomo_head.md)
 * [ghostfacenet_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/ghostfacenet_head.md)
 * [ocr_ctc_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/ocr_ctc_head.md)
 * [precision_bbox_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/precision_bbox_head.md)
 * [precision_seg_bbox_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/precision_seg_bbox_head.md)
 * [segmentation_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/segmentation_head.md)
 * [transformer_classification_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/transformer_classification_head.md)
 * [transformer_segmentation_head](https://docs.luxonis.com/software-v3/ai-inference/model-source/training/luxonis-train/luxonis-train-api-reference/nodes/heads/transformer_segmentation_head.md)