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# Copyright (c) Meta Platforms, Inc. and affiliates. | |
# All rights reserved. | |
# This source code is licensed under the license found in the | |
# LICENSE file in the root directory of this source tree. | |
import warnings | |
import torch | |
import torch.nn as nn | |
import torch.nn.functional as F | |
from torchvision.transforms import Normalize, Resize, ToTensor | |
class SAM2Transforms(nn.Module): | |
def __init__( | |
self, resolution, mask_threshold, max_hole_area=0.0, max_sprinkle_area=0.0 | |
): | |
""" | |
Transforms for SAM2. | |
""" | |
super().__init__() | |
self.resolution = resolution | |
self.mask_threshold = mask_threshold | |
self.max_hole_area = max_hole_area | |
self.max_sprinkle_area = max_sprinkle_area | |
self.mean = [0.485, 0.456, 0.406] | |
self.std = [0.229, 0.224, 0.225] | |
self.to_tensor = ToTensor() | |
self.transforms = torch.jit.script( | |
nn.Sequential( | |
Resize((self.resolution, self.resolution)), | |
Normalize(self.mean, self.std), | |
) | |
) | |
def __call__(self, x): | |
x = self.to_tensor(x) | |
return self.transforms(x) | |
def forward_batch(self, img_list): | |
img_batch = [self.transforms(self.to_tensor(img)) for img in img_list] | |
img_batch = torch.stack(img_batch, dim=0) | |
return img_batch | |
def transform_coords( | |
self, coords: torch.Tensor, normalize=False, orig_hw=None | |
) -> torch.Tensor: | |
""" | |
Expects a torch tensor with length 2 in the last dimension. The coordinates can be in absolute image or normalized coordinates, | |
If the coords are in absolute image coordinates, normalize should be set to True and original image size is required. | |
Returns | |
Un-normalized coordinates in the range of [0, 1] which is expected by the SAM2 model. | |
""" | |
if normalize: | |
assert orig_hw is not None | |
h, w = orig_hw | |
coords = coords.clone() | |
coords[..., 0] = coords[..., 0] / w | |
coords[..., 1] = coords[..., 1] / h | |
coords = coords * self.resolution # unnormalize coords | |
return coords | |
def transform_boxes( | |
self, boxes: torch.Tensor, normalize=False, orig_hw=None | |
) -> torch.Tensor: | |
""" | |
Expects a tensor of shape Bx4. The coordinates can be in absolute image or normalized coordinates, | |
if the coords are in absolute image coordinates, normalize should be set to True and original image size is required. | |
""" | |
boxes = self.transform_coords(boxes.reshape(-1, 2, 2), normalize, orig_hw) | |
return boxes | |
def postprocess_masks(self, masks: torch.Tensor, orig_hw) -> torch.Tensor: | |
""" | |
Perform PostProcessing on output masks. | |
""" | |
from sam2.utils.misc import get_connected_components | |
masks = masks.float() | |
input_masks = masks | |
mask_flat = masks.flatten(0, 1).unsqueeze(1) # flatten as 1-channel image | |
try: | |
if self.max_hole_area > 0: | |
# Holes are those connected components in background with area <= self.fill_hole_area | |
# (background regions are those with mask scores <= self.mask_threshold) | |
labels, areas = get_connected_components( | |
mask_flat <= self.mask_threshold | |
) | |
is_hole = (labels > 0) & (areas <= self.max_hole_area) | |
is_hole = is_hole.reshape_as(masks) | |
# We fill holes with a small positive mask score (10.0) to change them to foreground. | |
masks = torch.where(is_hole, self.mask_threshold + 10.0, masks) | |
if self.max_sprinkle_area > 0: | |
labels, areas = get_connected_components( | |
mask_flat > self.mask_threshold | |
) | |
is_hole = (labels > 0) & (areas <= self.max_sprinkle_area) | |
is_hole = is_hole.reshape_as(masks) | |
# We fill holes with negative mask score (-10.0) to change them to background. | |
masks = torch.where(is_hole, self.mask_threshold - 10.0, masks) | |
except Exception as e: | |
# Skip the post-processing step if the CUDA kernel fails | |
warnings.warn( | |
f"{e}\n\nSkipping the post-processing step due to the error above. You can " | |
"still use SAM 2 and it's OK to ignore the error above, although some post-processing " | |
"functionality may be limited (which doesn't affect the results in most cases; see " | |
"https://github.com/facebookresearch/sam2/blob/main/INSTALL.md).", | |
category=UserWarning, | |
stacklevel=2, | |
) | |
masks = input_masks | |
masks = F.interpolate(masks, orig_hw, mode="bilinear", align_corners=False) | |
return masks | |