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# Ultralytics YOLO 🚀, AGPL-3.0 license
import torch
from ultralytics.engine.results import Results
from ultralytics.models.fastsam.utils import bbox_iou
from ultralytics.models.yolo.detect.predict import DetectionPredictor
from ultralytics.utils import DEFAULT_CFG, ops
class FastSAMPredictor(DetectionPredictor):
"""
FastSAMPredictor is specialized for fast SAM (Segment Anything Model) segmentation prediction tasks in Ultralytics
YOLO framework.
This class extends the DetectionPredictor, customizing the prediction pipeline specifically for fast SAM.
It adjusts post-processing steps to incorporate mask prediction and non-max suppression while optimizing
for single-class segmentation.
Attributes:
cfg (dict): Configuration parameters for prediction.
overrides (dict, optional): Optional parameter overrides for custom behavior.
_callbacks (dict, optional): Optional list of callback functions to be invoked during prediction.
"""
def __init__(self, cfg=DEFAULT_CFG, overrides=None, _callbacks=None):
"""
Initializes the FastSAMPredictor class, inheriting from DetectionPredictor and setting the task to 'segment'.
Args:
cfg (dict): Configuration parameters for prediction.
overrides (dict, optional): Optional parameter overrides for custom behavior.
_callbacks (dict, optional): Optional list of callback functions to be invoked during prediction.
"""
super().__init__(cfg, overrides, _callbacks)
self.args.task = 'segment'
def postprocess(self, preds, img, orig_imgs):
"""
Perform post-processing steps on predictions, including non-max suppression and scaling boxes to original image
size, and returns the final results.
Args:
preds (list): The raw output predictions from the model.
img (torch.Tensor): The processed image tensor.
orig_imgs (list | torch.Tensor): The original image or list of images.
Returns:
(list): A list of Results objects, each containing processed boxes, masks, and other metadata.
"""
p = ops.non_max_suppression(
preds[0],
self.args.conf,
self.args.iou,
agnostic=self.args.agnostic_nms,
max_det=self.args.max_det,
nc=1, # set to 1 class since SAM has no class predictions
classes=self.args.classes)
full_box = torch.zeros(p[0].shape[1], device=p[0].device)
full_box[2], full_box[3], full_box[4], full_box[6:] = img.shape[3], img.shape[2], 1.0, 1.0
full_box = full_box.view(1, -1)
critical_iou_index = bbox_iou(full_box[0][:4], p[0][:, :4], iou_thres=0.9, image_shape=img.shape[2:])
if critical_iou_index.numel() != 0:
full_box[0][4] = p[0][critical_iou_index][:, 4]
full_box[0][6:] = p[0][critical_iou_index][:, 6:]
p[0][critical_iou_index] = full_box
if not isinstance(orig_imgs, list): # input images are a torch.Tensor, not a list
orig_imgs = ops.convert_torch2numpy_batch(orig_imgs)
results = []
proto = preds[1][-1] if len(preds[1]) == 3 else preds[1] # second output is len 3 if pt, but only 1 if exported
for i, pred in enumerate(p):
orig_img = orig_imgs[i]
img_path = self.batch[0][i]
if not len(pred): # save empty boxes
masks = None
elif self.args.retina_masks:
pred[:, :4] = ops.scale_boxes(img.shape[2:], pred[:, :4], orig_img.shape)
masks = ops.process_mask_native(proto[i], pred[:, 6:], pred[:, :4], orig_img.shape[:2]) # HWC
else:
masks = ops.process_mask(proto[i], pred[:, 6:], pred[:, :4], img.shape[2:], upsample=True) # HWC
pred[:, :4] = ops.scale_boxes(img.shape[2:], pred[:, :4], orig_img.shape)
results.append(Results(orig_img, path=img_path, names=self.model.names, boxes=pred[:, :6], masks=masks))
return results