# Ultralytics 🚀 AGPL-3.0 License - https://ultralytics.com/license from __future__ import annotations import torch from PIL import Image from ultralytics.models.yolo.segment import SegmentationPredictor from ultralytics.utils import DEFAULT_CFG from ultralytics.utils.metrics import box_iou from ultralytics.utils.ops import scale_masks from ultralytics.utils.torch_utils import TORCH_1_10 from .utils import adjust_bboxes_to_image_border class FastSAMPredictor(SegmentationPredictor): """FastSAMPredictor is specialized for fast SAM (Segment Anything Model) segmentation prediction tasks. This class extends the SegmentationPredictor, customizing the prediction pipeline specifically for fast SAM. It adjusts post-processing steps to incorporate mask prediction and non-maximum suppression while optimizing for single-class segmentation. Attributes: prompts (dict): Dictionary containing prompt information for segmentation (bboxes, points, labels, texts). device (torch.device): Device on which model and tensors are processed. clip (Any, optional): CLIP model used for text-based prompting, loaded on demand. Methods: postprocess: Apply postprocessing to FastSAM predictions and handle prompts. prompt: Perform image segmentation inference based on various prompt types. set_prompts: Set prompts to be used during inference. """ def __init__(self, cfg=DEFAULT_CFG, overrides=None, _callbacks: dict | None = None): """Initialize the FastSAMPredictor with configuration and callbacks. This initializes a predictor specialized for Fast SAM (Segment Anything Model) segmentation tasks. The predictor extends SegmentationPredictor with custom post-processing for mask prediction and non-maximum suppression optimized for single-class segmentation. Args: cfg (dict): Configuration for the predictor. overrides (dict, optional): Configuration overrides. _callbacks (dict, optional): Dictionary of callback functions. """ super().__init__(cfg, overrides, _callbacks) self.prompts = {} def postprocess(self, preds, img, orig_imgs): """Apply postprocessing to FastSAM predictions and handle prompts. Args: preds (list[torch.Tensor]): Raw predictions from the model. img (torch.Tensor): Input image tensor that was fed to the model. orig_imgs (list[np.ndarray]): Original images before preprocessing. Returns: (list[Results]): Processed results with prompts applied. """ bboxes = self.prompts.pop("bboxes", None) points = self.prompts.pop("points", None) labels = self.prompts.pop("labels", None) texts = self.prompts.pop("texts", None) results = super().postprocess(preds, img, orig_imgs) for result in results: full_box = torch.tensor( [0, 0, result.orig_shape[1], result.orig_shape[0]], device=result.boxes.data.device, dtype=torch.float32 ) boxes = adjust_bboxes_to_image_border(result.boxes.xyxy, result.orig_shape) idx = torch.nonzero(box_iou(full_box[None], boxes) > 0.9).flatten() if idx.numel() != 0: result.boxes.xyxy[idx] = full_box return self.prompt(results, bboxes=bboxes, points=points, labels=labels, texts=texts) def prompt(self, results, bboxes=None, points=None, labels=None, texts=None): """Perform image segmentation inference based on cues like bounding boxes, points, and text prompts. Args: results (Results | list[Results]): Original inference results from FastSAM models without any prompts. bboxes (np.ndarray | list, optional): Bounding boxes with shape (N, 4), in XYXY format. points (np.ndarray | list, optional): Points indicating object locations with shape (N, 2), in pixels. labels (np.ndarray | list, optional): Labels for point prompts, shape (N, ). 1 = foreground, 0 = background. texts (str | list[str], optional): Textual prompts, a list containing string objects. Returns: (list[Results]): Output results filtered and determined by the provided prompts. """ if bboxes is None and points is None and texts is None: return results prompt_results = [] if not isinstance(results, list): results = [results] for result in results: if len(result) == 0: prompt_results.append(result) continue masks = result.masks.data if masks.shape[1:] != result.orig_shape: masks = (scale_masks(masks[None].float(), result.orig_shape)[0] > 0.5).byte() # bboxes prompt idx = torch.zeros(len(result), dtype=torch.bool, device=self.device) if bboxes is not None: bboxes = torch.as_tensor(bboxes, dtype=torch.int32, device=self.device) bboxes = bboxes[None] if bboxes.ndim == 1 else bboxes bbox_areas = (bboxes[:, 3] - bboxes[:, 1]) * (bboxes[:, 2] - bboxes[:, 0]) mask_areas = torch.stack([masks[:, b[1] : b[3], b[0] : b[2]].sum(dim=(1, 2)) for b in bboxes]) full_mask_areas = torch.sum(masks, dim=(1, 2)) union = bbox_areas[:, None] + full_mask_areas - mask_areas idx[torch.argmax(mask_areas / union, dim=1)] = True if points is not None: points = torch.as_tensor(points, dtype=torch.int32, device=self.device) points = points[None] if points.ndim == 1 else points if labels is None: labels = torch.ones(points.shape[0]) labels = torch.as_tensor(labels, dtype=torch.int32, device=self.device) assert len(labels) == len(points), ( f"Expected `labels` to have the same length as `points`, but got {len(labels)} and {len(points)}." ) point_idx = ( torch.ones(len(result), dtype=torch.bool, device=self.device) if labels.sum() == 0 # all negative points else torch.zeros(len(result), dtype=torch.bool, device=self.device) ) for point, label in zip(points, labels): point_idx[torch.nonzero(masks[:, point[1], point[0]], as_tuple=True)[0]] = bool(label) idx |= point_idx if texts is not None: if isinstance(texts, str): texts = [texts] crop_ims, filter_idx = [], [] for i, b in enumerate(result.boxes.xyxy.tolist()): x1, y1, x2, y2 = (int(x) for x in b) if (masks[i].sum() if TORCH_1_10 else masks[i].sum(0).sum()) <= 100: # torch 1.9 bug workaround filter_idx.append(i) continue crop = result.orig_img[y1:y2, x1:x2] * masks[i, y1:y2, x1:x2, None].cpu().numpy() crop_ims.append(Image.fromarray(crop[:, :, ::-1])) similarity = self._clip_inference(crop_ims, texts) text_idx = torch.argmax(similarity, dim=-1) # (M, ) if len(filter_idx): # Remap text_idx to its original index before filter ori_idxs = [i for i in range(len(result)) if i not in filter_idx] text_idx = torch.tensor(ori_idxs[int(text_idx)], device=self.device) idx[text_idx] = True prompt_results.append(result[idx]) return prompt_results def _clip_inference(self, images, texts): """Perform CLIP inference to calculate similarity between images and text prompts. Args: images (list[PIL.Image]): List of source images, each should be PIL.Image with RGB channel order. texts (list[str]): List of prompt texts, each should be a string object. Returns: (torch.Tensor): Similarity matrix between given images and texts with shape (M, N). """ from ultralytics.nn.text_model import CLIP if not hasattr(self, "clip"): self.clip = CLIP("ViT-B/32", device=self.device) images = torch.stack([self.clip.image_preprocess(image).to(self.device) for image in images]) image_features = self.clip.encode_image(images) text_features = self.clip.encode_text(self.clip.tokenize(texts)) return text_features @ image_features.T # (M, N) def set_prompts(self, prompts): """Set prompts to be used during inference.""" self.prompts = prompts