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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 torch
from torch import nn
from torch.nn import functional as F

from typing import Any, Dict, List, Tuple

from .image_encoder import ImageEncoderViT
from .mask_decoder import MaskDecoder
from .prompt_encoder import PromptEncoder


class Sam(nn.Module):
    mask_threshold: float = 0.0
    image_format: str = "RGB"

    def __init__(

        self,

        image_encoder: ImageEncoderViT,

        prompt_encoder: PromptEncoder,

        mask_decoder: MaskDecoder,

        pixel_mean: List[float] = [123.675, 116.28, 103.53],

        pixel_std: List[float] = [58.395, 57.12, 57.375],

    ) -> None:
        """

        SAM predicts object masks from an image and input prompts.



        Arguments:

          image_encoder (ImageEncoderViT): The backbone used to encode the

            image into image embeddings that allow for efficient mask prediction.

          prompt_encoder (PromptEncoder): Encodes various types of input prompts.

          mask_decoder (MaskDecoder): Predicts masks from the image embeddings

            and encoded prompts.

          pixel_mean (list(float)): Mean values for normalizing pixels in the input image.

          pixel_std (list(float)): Std values for normalizing pixels in the input image.

        """
        super().__init__()
        self.image_encoder = image_encoder
        self.prompt_encoder = prompt_encoder
        self.mask_decoder = mask_decoder
        self.register_buffer("pixel_mean", torch.Tensor(pixel_mean).view(-1, 1, 1), False)
        self.register_buffer("pixel_std", torch.Tensor(pixel_std).view(-1, 1, 1), False)

    @property
    def device(self) -> Any:
        return self.pixel_mean.device

    # @torch.no_grad()
    def forward(

        self,

        batched_input: List[Dict[str, Any]],

        multimask_output: bool,

    ) -> List[Dict[str, torch.Tensor]]:
        """

        Predicts masks end-to-end from provided images and prompts.

        If prompts are not known in advance, using SamPredictor is

        recommended over calling the model directly.



        Arguments:

          batched_input (list(dict)): A list over input images, each a

            dictionary with the following keys. A prompt key can be

            excluded if it is not present.

              'image': The image as a torch tensor in 3xHxW format,

                already transformed for input to the model.

              'original_size': (tuple(int, int)) The original size of

                the image before transformation, as (H, W).

              'point_coords': (torch.Tensor) Batched point prompts for

                this image, with shape BxNx2. Already transformed to the

                input frame of the model.

              'point_labels': (torch.Tensor) Batched labels for point prompts,

                with shape BxN.

              'boxes': (torch.Tensor) Batched box inputs, with shape Bx4.

                Already transformed to the input frame of the model.

              'mask_inputs': (torch.Tensor) Batched mask inputs to the model,

                in the form Bx1xHxW.

          multimask_output (bool): Whether the model should predict multiple

            disambiguating masks, or return a single mask.



        Returns:

          (list(dict)): A list over input images, where each element is

            as dictionary with the following keys.

              'masks': (torch.Tensor) Batched binary mask predictions,

                with shape BxCxHxW, where B is the number of input prompts,

                C is determined by multimask_output, and (H, W) is the

                original size of the image.

              'iou_predictions': (torch.Tensor) The model's predictions

                of mask quality, in shape BxC.

              'low_res_logits': (torch.Tensor) Low resolution logits with

                shape BxCxHxW, where H=W=256. Can be passed as mask input

                to subsequent iterations of prediction.

        """
        input_images = torch.stack([self.preprocess(x["image"]) for x in batched_input], dim=0)
        image_embeddings = self.image_encoder(input_images)

        outputs = []
        for image_record, curr_embedding in zip(batched_input, image_embeddings):
            if "point_coords" in image_record:
                points = (image_record["point_coords"], image_record["point_labels"])
            else:
                points = None
            sparse_embeddings, dense_embeddings = self.prompt_encoder(
                points=points,
                boxes=image_record.get("boxes", None),
                masks=image_record.get("mask_inputs", None),
            )
            low_res_masks, iou_predictions = self.mask_decoder(
                image_embeddings=curr_embedding.unsqueeze(0),
                image_pe=self.prompt_encoder.get_dense_pe(),
                sparse_prompt_embeddings=sparse_embeddings,
                dense_prompt_embeddings=dense_embeddings,
                multimask_output=multimask_output,
            )
            masks = self.postprocess_masks(
                low_res_masks,
                input_size=image_record["image"].shape[-2:],
                original_size=image_record["original_size"],
            )
            masks = masks > self.mask_threshold
            outputs.append(
                {
                    "masks": masks,
                    "iou_predictions": iou_predictions,
                    "low_res_logits": low_res_masks,
                }
            )
        return outputs

    def postprocess_masks(

        self,

        masks: torch.Tensor,

        input_size: Tuple[int, ...],

        original_size: Tuple[int, ...],

    ) -> torch.Tensor:
        """

        Remove padding and upscale masks to the original image size.



        Arguments:

          masks (torch.Tensor): Batched masks from the mask_decoder,

            in BxCxHxW format.

          input_size (tuple(int, int)): The size of the image input to the

            model, in (H, W) format. Used to remove padding.

          original_size (tuple(int, int)): The original size of the image

            before resizing for input to the model, in (H, W) format.



        Returns:

          (torch.Tensor): Batched masks in BxCxHxW format, where (H, W)

            is given by original_size.

        """
        masks = F.interpolate(
            masks,
            (self.image_encoder.img_size, self.image_encoder.img_size),
            mode="nearest"
        )
        masks = masks[..., : input_size[0], : input_size[1]]
        masks = F.interpolate(masks, original_size, mode="nearest")
        return masks

    def preprocess(self, x: torch.Tensor) -> torch.Tensor:
        """Normalize pixel values and pad to a square input."""
        # Normalize colors
        x = (x - self.pixel_mean) / self.pixel_std

        # Pad
        h, w = x.shape[-2:]
        padh = self.image_encoder.img_size - h
        padw = self.image_encoder.img_size - w
        x = F.pad(x, (0, padw, 0, padh))
        return x


class SamBatched(nn.Module):
    mask_threshold: float = 0.0
    image_format: str = "RGB"

    def __init__(

        self,

        image_encoder: ImageEncoderViT,

        prompt_encoder: PromptEncoder,

        mask_decoder: MaskDecoder,

        pixel_mean: List[float] = [123.675, 116.28, 103.53],

        pixel_std: List[float] = [58.395, 57.12, 57.375],

    ) -> None:
        """

        SAM predicts object masks from an image and input prompts.



        Arguments:

          image_encoder (ImageEncoderViT): The backbone used to encode the

            image into image embeddings that allow for efficient mask prediction.

          prompt_encoder (PromptEncoder): Encodes various types of input prompts.

          mask_decoder (MaskDecoder): Predicts masks from the image embeddings

            and encoded prompts.

          pixel_mean (list(float)): Mean values for normalizing pixels in the input image.

          pixel_std (list(float)): Std values for normalizing pixels in the input image.

        """
        super().__init__()
        self.image_encoder = image_encoder
        self.prompt_encoder = prompt_encoder
        self.mask_decoder = mask_decoder
        self.register_buffer("pixel_mean", torch.Tensor(pixel_mean).view(-1, 1, 1), False)
        self.register_buffer("pixel_std", torch.Tensor(pixel_std).view(-1, 1, 1), False)

    @property
    def device(self) -> Any:
        return self.pixel_mean.device

    # @torch.no_grad()
    def forward(

        self,

        batched_input: torch.Tensor,

        multimask_output: bool,

    ) -> List[Dict[str, torch.Tensor]]:
        """

        Predicts masks end-to-end from provided images and prompts.

        If prompts are not known in advance, using SamPredictor is

        recommended over calling the model directly.



        Arguments:

          batched_input (list(dict)): A list over input images, each a

            dictionary with the following keys. A prompt key can be

            excluded if it is not present.

              'image': The image as a torch tensor in 3xHxW format,

                already transformed for input to the model.

              'original_size': (tuple(int, int)) The original size of

                the image before transformation, as (H, W).

              'point_coords': (torch.Tensor) Batched point prompts for

                this image, with shape BxNx2. Already transformed to the

                input frame of the model.

              'point_labels': (torch.Tensor) Batched labels for point prompts,

                with shape BxN.

              'boxes': (torch.Tensor) Batched box inputs, with shape Bx4.

                Already transformed to the input frame of the model.

              'mask_inputs': (torch.Tensor) Batched mask inputs to the model,

                in the form Bx1xHxW.

          multimask_output (bool): Whether the model should predict multiple

            disambiguating masks, or return a single mask.



        Returns:

          (list(dict)): A list over input images, where each element is

            as dictionary with the following keys.

              'masks': (torch.Tensor) Batched binary mask predictions,

                with shape BxCxHxW, where B is the number of input prompts,

                C is determined by multimask_output, and (H, W) is the

                original size of the image.

              'iou_predictions': (torch.Tensor) The model's predictions

                of mask quality, in shape BxC.

              'low_res_logits': (torch.Tensor) Low resolution logits with

                shape BxCxHxW, where H=W=256. Can be passed as mask input

                to subsequent iterations of prediction.

        """
        with torch.no_grad():
            input_images = torch.stack([self.preprocess(x["image"]) for x in batched_input], dim=0)
            image_embeddings = self.image_encoder(input_images)

        outputs = []
        for image_record, curr_embedding in zip(batched_input, image_embeddings):
            if "point_coords" in image_record:
                points = (image_record["point_coords"], image_record["point_labels"])
            else:
                points = None
            sparse_embeddings, dense_embeddings = self.prompt_encoder(
                points=points,
                boxes=image_record.get("boxes", None),
                masks=image_record.get("mask_inputs", None),
            )
            low_res_masks, iou_predictions = self.mask_decoder(
                image_embeddings=curr_embedding.unsqueeze(0),
                image_pe=self.prompt_encoder.get_dense_pe(),
                sparse_prompt_embeddings=sparse_embeddings,
                dense_prompt_embeddings=dense_embeddings,
                multimask_output=multimask_output,
            )
            masks = self.postprocess_masks(
                low_res_masks,
                input_size=image_record["image_size"],
                original_size=image_record["original_size"],
            )
            masks = masks > self.mask_threshold
            outputs.append(
                {
                    "masks": masks,
                    "iou_predictions": iou_predictions,
                    "low_res_logits": low_res_masks,
                }
            )
        return outputs

    def postprocess_masks(

        self,

        masks: torch.Tensor,

        input_size: Tuple[int, ...],

        original_size: Tuple[int, ...],

    ) -> torch.Tensor:
        """

        Remove padding and upscale masks to the original image size.



        Arguments:

          masks (torch.Tensor): Batched masks from the mask_decoder,

            in BxCxHxW format.

          input_size (tuple(int, int)): The size of the image input to the

            model, in (H, W) format. Used to remove padding.

          original_size (tuple(int, int)): The original size of the image

            before resizing for input to the model, in (H, W) format.



        Returns:

          (torch.Tensor): Batched masks in BxCxHxW format, where (H, W)

            is given by original_size.

        """
        masks = F.interpolate(
            masks,
            (self.image_encoder.img_size, self.image_encoder.img_size),
            mode="bilinear",
            align_corners=True,
        )
        masks = masks[..., : int(input_size[0]), : int(input_size[1])]
        masks = F.interpolate(masks, original_size, mode="bilinear", align_corners=True)
        return masks

    def preprocess(self, x: torch.Tensor) -> torch.Tensor:
        """Normalize pixel values and pad to a square input."""
        # Normalize colors
        x = (x - self.pixel_mean) / self.pixel_std

        # Pad
        h, w = x.shape[-2:]
        padh = self.image_encoder.img_size - h
        padw = self.image_encoder.img_size - w
        x = F.pad(x, (0, padw, 0, padh))
        return x