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modeling_yolos.py
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modeling_yolos.py
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# coding=utf-8
# Copyright 2022 School of EIC, Huazhong University of Science & Technology and The HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
""" PyTorch YOLOS model."""
import collections.abc
import math
from dataclasses import dataclass
from typing import Dict, List, Optional, Set, Tuple, Union
import torch
import torch.utils.checkpoint
from torch import Tensor, nn
from ...activations import ACT2FN
from ...modeling_outputs import BaseModelOutput, BaseModelOutputWithPooling
from ...modeling_utils import PreTrainedModel
from ...pytorch_utils import find_pruneable_heads_and_indices, prune_linear_layer
from ...utils import (
ModelOutput,
add_code_sample_docstrings,
add_start_docstrings,
add_start_docstrings_to_model_forward,
is_scipy_available,
is_vision_available,
logging,
replace_return_docstrings,
requires_backends,
)
from .configuration_yolos import YolosConfig
if is_scipy_available():
from scipy.optimize import linear_sum_assignment
if is_vision_available():
from transformers.image_transforms import center_to_corners_format
logger = logging.get_logger(__name__)
# General docstring
_CONFIG_FOR_DOC = "YolosConfig"
# Base docstring
_CHECKPOINT_FOR_DOC = "hustvl/yolos-small"
_EXPECTED_OUTPUT_SHAPE = [1, 3401, 384]
YOLOS_PRETRAINED_MODEL_ARCHIVE_LIST = [
"hustvl/yolos-small",
# See all YOLOS models at https://huggingface.co/models?filter=yolos
]
@dataclass
class YolosObjectDetectionOutput(ModelOutput):
"""
Output type of [`YolosForObjectDetection`].
Args:
loss (`torch.FloatTensor` of shape `(1,)`, *optional*, returned when `labels` are provided)):
Total loss as a linear combination of a negative log-likehood (cross-entropy) for class prediction and a
bounding box loss. The latter is defined as a linear combination of the L1 loss and the generalized
scale-invariant IoU loss.
loss_dict (`Dict`, *optional*):
A dictionary containing the individual losses. Useful for logging.
logits (`torch.FloatTensor` of shape `(batch_size, num_queries, num_classes + 1)`):
Classification logits (including no-object) for all queries.
pred_boxes (`torch.FloatTensor` of shape `(batch_size, num_queries, 4)`):
Normalized boxes coordinates for all queries, represented as (center_x, center_y, width, height). These
values are normalized in [0, 1], relative to the size of each individual image in the batch (disregarding
possible padding). You can use [`~YolosImageProcessor.post_process`] to retrieve the unnormalized bounding
boxes.
auxiliary_outputs (`list[Dict]`, *optional*):
Optional, only returned when auxilary losses are activated (i.e. `config.auxiliary_loss` is set to `True`)
and labels are provided. It is a list of dictionaries containing the two above keys (`logits` and
`pred_boxes`) for each decoder layer.
last_hidden_state (`torch.FloatTensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*):
Sequence of hidden-states at the output of the last layer of the decoder of the model.
hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `torch.FloatTensor` (one for the output of the embeddings, if the model has an embedding layer, +
one for the output of each layer) of shape `(batch_size, sequence_length, hidden_size)`. Hidden-states of
the model at the output of each layer plus the optional initial embedding outputs.
attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`. Attentions weights after the attention softmax, used to compute the weighted average in
the self-attention heads.
"""
loss: Optional[torch.FloatTensor] = None
loss_dict: Optional[Dict] = None
logits: torch.FloatTensor = None
pred_boxes: torch.FloatTensor = None
auxiliary_outputs: Optional[List[Dict]] = None
last_hidden_state: Optional[torch.FloatTensor] = None
hidden_states: Optional[Tuple[torch.FloatTensor]] = None
attentions: Optional[Tuple[torch.FloatTensor]] = None
class YolosEmbeddings(nn.Module):
"""
Construct the CLS token, detection tokens, position and patch embeddings.
"""
def __init__(self, config: YolosConfig) -> None:
super().__init__()
self.cls_token = nn.Parameter(torch.zeros(1, 1, config.hidden_size))
self.detection_tokens = nn.Parameter(torch.zeros(1, config.num_detection_tokens, config.hidden_size))
self.patch_embeddings = YolosPatchEmbeddings(config)
num_patches = self.patch_embeddings.num_patches
self.position_embeddings = nn.Parameter(
torch.zeros(1, num_patches + config.num_detection_tokens + 1, config.hidden_size)
)
self.dropout = nn.Dropout(config.hidden_dropout_prob)
self.interpolation = InterpolateInitialPositionEmbeddings(config)
self.config = config
def forward(self, pixel_values: torch.Tensor) -> torch.Tensor:
batch_size, num_channels, height, width = pixel_values.shape
embeddings = self.patch_embeddings(pixel_values)
batch_size, seq_len, _ = embeddings.size()
# add the [CLS] and detection tokens to the embedded patch tokens
cls_tokens = self.cls_token.expand(batch_size, -1, -1)
detection_tokens = self.detection_tokens.expand(batch_size, -1, -1)
embeddings = torch.cat((cls_tokens, embeddings, detection_tokens), dim=1)
# add positional encoding to each token
# this might require interpolation of the existing position embeddings
position_embeddings = self.interpolation(self.position_embeddings, (height, width))
embeddings = embeddings + position_embeddings
embeddings = self.dropout(embeddings)
return embeddings
class InterpolateInitialPositionEmbeddings(nn.Module):
def __init__(self, config) -> None:
super().__init__()
self.config = config
def forward(self, pos_embed, img_size=(800, 1344)) -> torch.Tensor:
cls_pos_embed = pos_embed[:, 0, :]
cls_pos_embed = cls_pos_embed[:, None]
det_pos_embed = pos_embed[:, -self.config.num_detection_tokens :, :]
patch_pos_embed = pos_embed[:, 1 : -self.config.num_detection_tokens, :]
patch_pos_embed = patch_pos_embed.transpose(1, 2)
batch_size, hidden_size, seq_len = patch_pos_embed.shape
patch_height, patch_width = (
self.config.image_size[0] // self.config.patch_size,
self.config.image_size[1] // self.config.patch_size,
)
patch_pos_embed = patch_pos_embed.view(batch_size, hidden_size, patch_height, patch_width)
height, width = img_size
new_patch_heigth, new_patch_width = height // self.config.patch_size, width // self.config.patch_size
patch_pos_embed = nn.functional.interpolate(
patch_pos_embed, size=(new_patch_heigth, new_patch_width), mode="bicubic", align_corners=False
)
patch_pos_embed = patch_pos_embed.flatten(2).transpose(1, 2)
scale_pos_embed = torch.cat((cls_pos_embed, patch_pos_embed, det_pos_embed), dim=1)
return scale_pos_embed
class InterpolateMidPositionEmbeddings(nn.Module):
def __init__(self, config) -> None:
super().__init__()
self.config = config
def forward(self, pos_embed, img_size=(800, 1344)) -> torch.Tensor:
cls_pos_embed = pos_embed[:, :, 0, :]
cls_pos_embed = cls_pos_embed[:, None]
det_pos_embed = pos_embed[:, :, -self.config.num_detection_tokens :, :]
patch_pos_embed = pos_embed[:, :, 1 : -self.config.num_detection_tokens, :]
patch_pos_embed = patch_pos_embed.transpose(2, 3)
depth, batch_size, hidden_size, seq_len = patch_pos_embed.shape
patch_height, patch_width = (
self.config.image_size[0] // self.config.patch_size,
self.config.image_size[1] // self.config.patch_size,
)
patch_pos_embed = patch_pos_embed.view(depth * batch_size, hidden_size, patch_height, patch_width)
height, width = img_size
new_patch_height, new_patch_width = height // self.config.patch_size, width // self.config.patch_size
patch_pos_embed = nn.functional.interpolate(
patch_pos_embed, size=(new_patch_height, new_patch_width), mode="bicubic", align_corners=False
)
patch_pos_embed = (
patch_pos_embed.flatten(2)
.transpose(1, 2)
.contiguous()
.view(depth, batch_size, new_patch_height * new_patch_width, hidden_size)
)
scale_pos_embed = torch.cat((cls_pos_embed, patch_pos_embed, det_pos_embed), dim=2)
return scale_pos_embed
class YolosPatchEmbeddings(nn.Module):
"""
This class turns `pixel_values` of shape `(batch_size, num_channels, height, width)` into the initial
`hidden_states` (patch embeddings) of shape `(batch_size, seq_length, hidden_size)` to be consumed by a
Transformer.
"""
def __init__(self, config):
super().__init__()
image_size, patch_size = config.image_size, config.patch_size
num_channels, hidden_size = config.num_channels, config.hidden_size
image_size = image_size if isinstance(image_size, collections.abc.Iterable) else (image_size, image_size)
patch_size = patch_size if isinstance(patch_size, collections.abc.Iterable) else (patch_size, patch_size)
num_patches = (image_size[1] // patch_size[1]) * (image_size[0] // patch_size[0])
self.image_size = image_size
self.patch_size = patch_size
self.num_channels = num_channels
self.num_patches = num_patches
self.projection = nn.Conv2d(num_channels, hidden_size, kernel_size=patch_size, stride=patch_size)
def forward(self, pixel_values: torch.Tensor) -> torch.Tensor:
batch_size, num_channels, height, width = pixel_values.shape
if num_channels != self.num_channels:
raise ValueError(
"Make sure that the channel dimension of the pixel values match with the one set in the configuration."
)
embeddings = self.projection(pixel_values).flatten(2).transpose(1, 2)
return embeddings
# Copied from transformers.models.vit.modeling_vit.ViTSelfAttention with ViT->Yolos
class YolosSelfAttention(nn.Module):
def __init__(self, config: YolosConfig) -> None:
super().__init__()
if config.hidden_size % config.num_attention_heads != 0 and not hasattr(config, "embedding_size"):
raise ValueError(
f"The hidden size {config.hidden_size,} is not a multiple of the number of attention "
f"heads {config.num_attention_heads}."
)
self.num_attention_heads = config.num_attention_heads
self.attention_head_size = int(config.hidden_size / config.num_attention_heads)
self.all_head_size = self.num_attention_heads * self.attention_head_size
self.query = nn.Linear(config.hidden_size, self.all_head_size, bias=config.qkv_bias)
self.key = nn.Linear(config.hidden_size, self.all_head_size, bias=config.qkv_bias)
self.value = nn.Linear(config.hidden_size, self.all_head_size, bias=config.qkv_bias)
self.dropout = nn.Dropout(config.attention_probs_dropout_prob)
def transpose_for_scores(self, x: torch.Tensor) -> torch.Tensor:
new_x_shape = x.size()[:-1] + (self.num_attention_heads, self.attention_head_size)
x = x.view(new_x_shape)
return x.permute(0, 2, 1, 3)
def forward(
self, hidden_states, head_mask: Optional[torch.Tensor] = None, output_attentions: bool = False
) -> Union[Tuple[torch.Tensor, torch.Tensor], Tuple[torch.Tensor]]:
mixed_query_layer = self.query(hidden_states)
key_layer = self.transpose_for_scores(self.key(hidden_states))
value_layer = self.transpose_for_scores(self.value(hidden_states))
query_layer = self.transpose_for_scores(mixed_query_layer)
# Take the dot product between "query" and "key" to get the raw attention scores.
attention_scores = torch.matmul(query_layer, key_layer.transpose(-1, -2))
attention_scores = attention_scores / math.sqrt(self.attention_head_size)
# Normalize the attention scores to probabilities.
attention_probs = nn.functional.softmax(attention_scores, dim=-1)
# This is actually dropping out entire tokens to attend to, which might
# seem a bit unusual, but is taken from the original Transformer paper.
attention_probs = self.dropout(attention_probs)
# Mask heads if we want to
if head_mask is not None:
attention_probs = attention_probs * head_mask
context_layer = torch.matmul(attention_probs, value_layer)
context_layer = context_layer.permute(0, 2, 1, 3).contiguous()
new_context_layer_shape = context_layer.size()[:-2] + (self.all_head_size,)
context_layer = context_layer.view(new_context_layer_shape)
outputs = (context_layer, attention_probs) if output_attentions else (context_layer,)
return outputs
# Copied from transformers.models.vit.modeling_vit.ViTSelfOutput with ViT->Yolos
class YolosSelfOutput(nn.Module):
"""
The residual connection is defined in YolosLayer instead of here (as is the case with other models), due to the
layernorm applied before each block.
"""
def __init__(self, config: YolosConfig) -> None:
super().__init__()
self.dense = nn.Linear(config.hidden_size, config.hidden_size)
self.dropout = nn.Dropout(config.hidden_dropout_prob)
def forward(self, hidden_states: torch.Tensor, input_tensor: torch.Tensor) -> torch.Tensor:
hidden_states = self.dense(hidden_states)
hidden_states = self.dropout(hidden_states)
return hidden_states
# Copied from transformers.models.vit.modeling_vit.ViTAttention with ViT->Yolos
class YolosAttention(nn.Module):
def __init__(self, config: YolosConfig) -> None:
super().__init__()
self.attention = YolosSelfAttention(config)
self.output = YolosSelfOutput(config)
self.pruned_heads = set()
def prune_heads(self, heads: Set[int]) -> None:
if len(heads) == 0:
return
heads, index = find_pruneable_heads_and_indices(
heads, self.attention.num_attention_heads, self.attention.attention_head_size, self.pruned_heads
)
# Prune linear layers
self.attention.query = prune_linear_layer(self.attention.query, index)
self.attention.key = prune_linear_layer(self.attention.key, index)
self.attention.value = prune_linear_layer(self.attention.value, index)
self.output.dense = prune_linear_layer(self.output.dense, index, dim=1)
# Update hyper params and store pruned heads
self.attention.num_attention_heads = self.attention.num_attention_heads - len(heads)
self.attention.all_head_size = self.attention.attention_head_size * self.attention.num_attention_heads
self.pruned_heads = self.pruned_heads.union(heads)
def forward(
self,
hidden_states: torch.Tensor,
head_mask: Optional[torch.Tensor] = None,
output_attentions: bool = False,
) -> Union[Tuple[torch.Tensor, torch.Tensor], Tuple[torch.Tensor]]:
self_outputs = self.attention(hidden_states, head_mask, output_attentions)
attention_output = self.output(self_outputs[0], hidden_states)
outputs = (attention_output,) + self_outputs[1:] # add attentions if we output them
return outputs
# Copied from transformers.models.vit.modeling_vit.ViTIntermediate with ViT->Yolos
class YolosIntermediate(nn.Module):
def __init__(self, config: YolosConfig) -> None:
super().__init__()
self.dense = nn.Linear(config.hidden_size, config.intermediate_size)
if isinstance(config.hidden_act, str):
self.intermediate_act_fn = ACT2FN[config.hidden_act]
else:
self.intermediate_act_fn = config.hidden_act
def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
hidden_states = self.dense(hidden_states)
hidden_states = self.intermediate_act_fn(hidden_states)
return hidden_states
# Copied from transformers.models.vit.modeling_vit.ViTOutput with ViT->Yolos
class YolosOutput(nn.Module):
def __init__(self, config: YolosConfig) -> None:
super().__init__()
self.dense = nn.Linear(config.intermediate_size, config.hidden_size)
self.dropout = nn.Dropout(config.hidden_dropout_prob)
def forward(self, hidden_states: torch.Tensor, input_tensor: torch.Tensor) -> torch.Tensor:
hidden_states = self.dense(hidden_states)
hidden_states = self.dropout(hidden_states)
hidden_states = hidden_states + input_tensor
return hidden_states
# Copied from transformers.models.vit.modeling_vit.ViTLayer with ViT->Yolos
class YolosLayer(nn.Module):
"""This corresponds to the Block class in the timm implementation."""
def __init__(self, config: YolosConfig) -> None:
super().__init__()
self.chunk_size_feed_forward = config.chunk_size_feed_forward
self.seq_len_dim = 1
self.attention = YolosAttention(config)
self.intermediate = YolosIntermediate(config)
self.output = YolosOutput(config)
self.layernorm_before = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps)
self.layernorm_after = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps)
def forward(
self,
hidden_states: torch.Tensor,
head_mask: Optional[torch.Tensor] = None,
output_attentions: bool = False,
) -> Union[Tuple[torch.Tensor, torch.Tensor], Tuple[torch.Tensor]]:
self_attention_outputs = self.attention(
self.layernorm_before(hidden_states), # in Yolos, layernorm is applied before self-attention
head_mask,
output_attentions=output_attentions,
)
attention_output = self_attention_outputs[0]
outputs = self_attention_outputs[1:] # add self attentions if we output attention weights
# first residual connection
hidden_states = attention_output + hidden_states
# in Yolos, layernorm is also applied after self-attention
layer_output = self.layernorm_after(hidden_states)
layer_output = self.intermediate(layer_output)
# second residual connection is done here
layer_output = self.output(layer_output, hidden_states)
outputs = (layer_output,) + outputs
return outputs
class YolosEncoder(nn.Module):
def __init__(self, config: YolosConfig) -> None:
super().__init__()
self.config = config
self.layer = nn.ModuleList([YolosLayer(config) for _ in range(config.num_hidden_layers)])
self.gradient_checkpointing = False
seq_length = (
1 + (config.image_size[0] * config.image_size[1] // config.patch_size**2) + config.num_detection_tokens
)
self.mid_position_embeddings = (
nn.Parameter(
torch.zeros(
config.num_hidden_layers - 1,
1,
seq_length,
config.hidden_size,
)
)
if config.use_mid_position_embeddings
else None
)
self.interpolation = InterpolateMidPositionEmbeddings(config) if config.use_mid_position_embeddings else None
def forward(
self,
hidden_states: torch.Tensor,
height,
width,
head_mask: Optional[torch.Tensor] = None,
output_attentions: bool = False,
output_hidden_states: bool = False,
return_dict: bool = True,
) -> Union[tuple, BaseModelOutput]:
all_hidden_states = () if output_hidden_states else None
all_self_attentions = () if output_attentions else None
if self.config.use_mid_position_embeddings:
interpolated_mid_position_embeddings = self.interpolation(self.mid_position_embeddings, (height, width))
for i, layer_module in enumerate(self.layer):
if output_hidden_states:
all_hidden_states = all_hidden_states + (hidden_states,)
layer_head_mask = head_mask[i] if head_mask is not None else None
if self.gradient_checkpointing and self.training:
layer_outputs = self._gradient_checkpointing_func(
layer_module.__call__,
hidden_states,
layer_head_mask,
output_attentions,
)
else:
layer_outputs = layer_module(hidden_states, layer_head_mask, output_attentions)
hidden_states = layer_outputs[0]
if self.config.use_mid_position_embeddings:
if i < (self.config.num_hidden_layers - 1):
hidden_states = hidden_states + interpolated_mid_position_embeddings[i]
if output_attentions:
all_self_attentions = all_self_attentions + (layer_outputs[1],)
if output_hidden_states:
all_hidden_states = all_hidden_states + (hidden_states,)
if not return_dict:
return tuple(v for v in [hidden_states, all_hidden_states, all_self_attentions] if v is not None)
return BaseModelOutput(
last_hidden_state=hidden_states,
hidden_states=all_hidden_states,
attentions=all_self_attentions,
)
class YolosPreTrainedModel(PreTrainedModel):
"""
An abstract class to handle weights initialization and a simple interface for downloading and loading pretrained
models.
"""
config_class = YolosConfig
base_model_prefix = "vit"
main_input_name = "pixel_values"
supports_gradient_checkpointing = True
def _init_weights(self, module: Union[nn.Linear, nn.Conv2d, nn.LayerNorm]) -> None:
"""Initialize the weights"""
if isinstance(module, (nn.Linear, nn.Conv2d)):
# Slightly different from the TF version which uses truncated_normal for initialization
# cf https://github.com/pytorch/pytorch/pull/5617
module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
if module.bias is not None:
module.bias.data.zero_()
elif isinstance(module, nn.LayerNorm):
module.bias.data.zero_()
module.weight.data.fill_(1.0)
YOLOS_START_DOCSTRING = r"""
This model is a PyTorch [torch.nn.Module](https://pytorch.org/docs/stable/nn.html#torch.nn.Module) subclass. Use it
as a regular PyTorch Module and refer to the PyTorch documentation for all matter related to general usage and
behavior.
Parameters:
config ([`YolosConfig`]): Model configuration class with all the parameters of the model.
Initializing with a config file does not load the weights associated with the model, only the
configuration. Check out the [`~PreTrainedModel.from_pretrained`] method to load the model weights.
"""
YOLOS_INPUTS_DOCSTRING = r"""
Args:
pixel_values (`torch.FloatTensor` of shape `(batch_size, num_channels, height, width)`):
Pixel values. Pixel values can be obtained using [`AutoImageProcessor`]. See
[`YolosImageProcessor.__call__`] for details.
head_mask (`torch.FloatTensor` of shape `(num_heads,)` or `(num_layers, num_heads)`, *optional*):
Mask to nullify selected heads of the self-attention modules. Mask values selected in `[0, 1]`:
- 1 indicates the head is **not masked**,
- 0 indicates the head is **masked**.
output_attentions (`bool`, *optional*):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under returned
tensors for more detail.
output_hidden_states (`bool`, *optional*):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors for
more detail.
return_dict (`bool`, *optional*):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
"""
@add_start_docstrings(
"The bare YOLOS Model transformer outputting raw hidden-states without any specific head on top.",
YOLOS_START_DOCSTRING,
)
class YolosModel(YolosPreTrainedModel):
def __init__(self, config: YolosConfig, add_pooling_layer: bool = True):
super().__init__(config)
self.config = config
self.embeddings = YolosEmbeddings(config)
self.encoder = YolosEncoder(config)
self.layernorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps)
self.pooler = YolosPooler(config) if add_pooling_layer else None
# Initialize weights and apply final processing
self.post_init()
def get_input_embeddings(self) -> YolosPatchEmbeddings:
return self.embeddings.patch_embeddings
def _prune_heads(self, heads_to_prune: Dict[int, List[int]]) -> None:
"""
Prunes heads of the model.
Args:
heads_to_prune (`dict` of {layer_num: list of heads to prune in this layer}):
See base class `PreTrainedModel`.
"""
for layer, heads in heads_to_prune.items():
self.encoder.layer[layer].attention.prune_heads(heads)
@add_start_docstrings_to_model_forward(YOLOS_INPUTS_DOCSTRING)
@add_code_sample_docstrings(
checkpoint=_CHECKPOINT_FOR_DOC,
output_type=BaseModelOutputWithPooling,
config_class=_CONFIG_FOR_DOC,
modality="vision",
expected_output=_EXPECTED_OUTPUT_SHAPE,
)
def forward(
self,
pixel_values: Optional[torch.Tensor] = None,
head_mask: Optional[torch.Tensor] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
return_dict: Optional[bool] = None,
) -> Union[Tuple, BaseModelOutputWithPooling]:
output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
)
return_dict = return_dict if return_dict is not None else self.config.use_return_dict
if pixel_values is None:
raise ValueError("You have to specify pixel_values")
# Prepare head mask if needed
# 1.0 in head_mask indicate we keep the head
# attention_probs has shape bsz x n_heads x N x N
# input head_mask has shape [num_heads] or [num_hidden_layers x num_heads]
# and head_mask is converted to shape [num_hidden_layers x batch x num_heads x seq_length x seq_length]
head_mask = self.get_head_mask(head_mask, self.config.num_hidden_layers)
embedding_output = self.embeddings(pixel_values)
encoder_outputs = self.encoder(
embedding_output,
height=pixel_values.shape[-2],
width=pixel_values.shape[-1],
head_mask=head_mask,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
return_dict=return_dict,
)
sequence_output = encoder_outputs[0]
sequence_output = self.layernorm(sequence_output)
pooled_output = self.pooler(sequence_output) if self.pooler is not None else None
if not return_dict:
head_outputs = (sequence_output, pooled_output) if pooled_output is not None else (sequence_output,)
return head_outputs + encoder_outputs[1:]
return BaseModelOutputWithPooling(
last_hidden_state=sequence_output,
pooler_output=pooled_output,
hidden_states=encoder_outputs.hidden_states,
attentions=encoder_outputs.attentions,
)
class YolosPooler(nn.Module):
def __init__(self, config: YolosConfig):
super().__init__()
self.dense = nn.Linear(config.hidden_size, config.hidden_size)
self.activation = nn.Tanh()
def forward(self, hidden_states):
# We "pool" the model by simply taking the hidden state corresponding
# to the first token.
first_token_tensor = hidden_states[:, 0]
pooled_output = self.dense(first_token_tensor)
pooled_output = self.activation(pooled_output)
return pooled_output
@add_start_docstrings(
"""
YOLOS Model (consisting of a ViT encoder) with object detection heads on top, for tasks such as COCO detection.
""",
YOLOS_START_DOCSTRING,
)
class YolosForObjectDetection(YolosPreTrainedModel):
def __init__(self, config: YolosConfig):
super().__init__(config)
# YOLOS (ViT) encoder model
self.vit = YolosModel(config, add_pooling_layer=False)
# Object detection heads
# We add one for the "no object" class
self.class_labels_classifier = YolosMLPPredictionHead(
input_dim=config.hidden_size, hidden_dim=config.hidden_size, output_dim=config.num_labels + 1, num_layers=3
)
self.bbox_predictor = YolosMLPPredictionHead(
input_dim=config.hidden_size, hidden_dim=config.hidden_size, output_dim=4, num_layers=3
)
# Initialize weights and apply final processing
self.post_init()
# taken from https://github.com/facebookresearch/detr/blob/master/models/detr.py
@torch.jit.unused
def _set_aux_loss(self, outputs_class, outputs_coord):
# this is a workaround to make torchscript happy, as torchscript
# doesn't support dictionary with non-homogeneous values, such
# as a dict having both a Tensor and a list.
return [{"logits": a, "pred_boxes": b} for a, b in zip(outputs_class[:-1], outputs_coord[:-1])]
@add_start_docstrings_to_model_forward(YOLOS_INPUTS_DOCSTRING)
@replace_return_docstrings(output_type=YolosObjectDetectionOutput, config_class=_CONFIG_FOR_DOC)
def forward(
self,
pixel_values: torch.FloatTensor,
labels: Optional[List[Dict]] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
return_dict: Optional[bool] = None,
) -> Union[Tuple, YolosObjectDetectionOutput]:
r"""
labels (`List[Dict]` of len `(batch_size,)`, *optional*):
Labels for computing the bipartite matching loss. List of dicts, each dictionary containing at least the
following 2 keys: `'class_labels'` and `'boxes'` (the class labels and bounding boxes of an image in the
batch respectively). The class labels themselves should be a `torch.LongTensor` of len `(number of bounding
boxes in the image,)` and the boxes a `torch.FloatTensor` of shape `(number of bounding boxes in the image,
4)`.
Returns:
Examples:
```python
>>> from transformers import AutoImageProcessor, AutoModelForObjectDetection
>>> import torch
>>> from PIL import Image
>>> import requests
>>> url = "http://images.cocodataset.org/val2017/000000039769.jpg"
>>> image = Image.open(requests.get(url, stream=True).raw)
>>> image_processor = AutoImageProcessor.from_pretrained("hustvl/yolos-tiny")
>>> model = AutoModelForObjectDetection.from_pretrained("hustvl/yolos-tiny")
>>> inputs = image_processor(images=image, return_tensors="pt")
>>> outputs = model(**inputs)
>>> # convert outputs (bounding boxes and class logits) to Pascal VOC format (xmin, ymin, xmax, ymax)
>>> target_sizes = torch.tensor([image.size[::-1]])
>>> results = image_processor.post_process_object_detection(outputs, threshold=0.9, target_sizes=target_sizes)[
... 0
... ]
>>> for score, label, box in zip(results["scores"], results["labels"], results["boxes"]):
... box = [round(i, 2) for i in box.tolist()]
... print(
... f"Detected {model.config.id2label[label.item()]} with confidence "
... f"{round(score.item(), 3)} at location {box}"
... )
Detected remote with confidence 0.994 at location [46.96, 72.61, 181.02, 119.73]
Detected remote with confidence 0.975 at location [340.66, 79.19, 372.59, 192.65]
Detected cat with confidence 0.984 at location [12.27, 54.25, 319.42, 470.99]
Detected remote with confidence 0.922 at location [41.66, 71.96, 178.7, 120.33]
Detected cat with confidence 0.914 at location [342.34, 21.48, 638.64, 372.46]
```"""
return_dict = return_dict if return_dict is not None else self.config.use_return_dict
# First, sent images through YOLOS base model to obtain hidden states
outputs = self.vit(
pixel_values,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
return_dict=return_dict,
)
sequence_output = outputs[0]
# Take the final hidden states of the detection tokens
sequence_output = sequence_output[:, -self.config.num_detection_tokens :, :]
# Class logits + predicted bounding boxes
logits = self.class_labels_classifier(sequence_output)
pred_boxes = self.bbox_predictor(sequence_output).sigmoid()
loss, loss_dict, auxiliary_outputs = None, None, None
if labels is not None:
# First: create the matcher
matcher = YolosHungarianMatcher(
class_cost=self.config.class_cost, bbox_cost=self.config.bbox_cost, giou_cost=self.config.giou_cost
)
# Second: create the criterion
losses = ["labels", "boxes", "cardinality"]
criterion = YolosLoss(
matcher=matcher,
num_classes=self.config.num_labels,
eos_coef=self.config.eos_coefficient,
losses=losses,
)
criterion.to(self.device)
# Third: compute the losses, based on outputs and labels
outputs_loss = {}
outputs_loss["logits"] = logits
outputs_loss["pred_boxes"] = pred_boxes
if self.config.auxiliary_loss:
intermediate = outputs.intermediate_hidden_states if return_dict else outputs[4]
outputs_class = self.class_labels_classifier(intermediate)
outputs_coord = self.bbox_predictor(intermediate).sigmoid()
auxiliary_outputs = self._set_aux_loss(outputs_class, outputs_coord)
outputs_loss["auxiliary_outputs"] = auxiliary_outputs
loss_dict = criterion(outputs_loss, labels)
# Fourth: compute total loss, as a weighted sum of the various losses
weight_dict = {"loss_ce": 1, "loss_bbox": self.config.bbox_loss_coefficient}
weight_dict["loss_giou"] = self.config.giou_loss_coefficient
if self.config.auxiliary_loss:
aux_weight_dict = {}
for i in range(self.config.decoder_layers - 1):
aux_weight_dict.update({k + f"_{i}": v for k, v in weight_dict.items()})
weight_dict.update(aux_weight_dict)
loss = sum(loss_dict[k] * weight_dict[k] for k in loss_dict.keys() if k in weight_dict)
if not return_dict:
if auxiliary_outputs is not None:
output = (logits, pred_boxes) + auxiliary_outputs + outputs
else:
output = (logits, pred_boxes) + outputs
return ((loss, loss_dict) + output) if loss is not None else output
return YolosObjectDetectionOutput(
loss=loss,
loss_dict=loss_dict,
logits=logits,
pred_boxes=pred_boxes,
auxiliary_outputs=auxiliary_outputs,
last_hidden_state=outputs.last_hidden_state,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
)
# Copied from transformers.models.detr.modeling_detr.dice_loss
def dice_loss(inputs, targets, num_boxes):
"""
Compute the DICE loss, similar to generalized IOU for masks
Args:
inputs: A float tensor of arbitrary shape.
The predictions for each example.
targets: A float tensor with the same shape as inputs. Stores the binary
classification label for each element in inputs (0 for the negative class and 1 for the positive
class).
"""
inputs = inputs.sigmoid()
inputs = inputs.flatten(1)
numerator = 2 * (inputs * targets).sum(1)
denominator = inputs.sum(-1) + targets.sum(-1)
loss = 1 - (numerator + 1) / (denominator + 1)
return loss.sum() / num_boxes
# Copied from transformers.models.detr.modeling_detr.sigmoid_focal_loss
def sigmoid_focal_loss(inputs, targets, num_boxes, alpha: float = 0.25, gamma: float = 2):
"""
Loss used in RetinaNet for dense detection: https://arxiv.org/abs/1708.02002.
Args:
inputs (`torch.FloatTensor` of arbitrary shape):
The predictions for each example.
targets (`torch.FloatTensor` with the same shape as `inputs`)
A tensor storing the binary classification label for each element in the `inputs` (0 for the negative class
and 1 for the positive class).
alpha (`float`, *optional*, defaults to `0.25`):
Optional weighting factor in the range (0,1) to balance positive vs. negative examples.
gamma (`int`, *optional*, defaults to `2`):
Exponent of the modulating factor (1 - p_t) to balance easy vs hard examples.
Returns:
Loss tensor
"""
prob = inputs.sigmoid()
ce_loss = nn.functional.binary_cross_entropy_with_logits(inputs, targets, reduction="none")
# add modulating factor
p_t = prob * targets + (1 - prob) * (1 - targets)
loss = ce_loss * ((1 - p_t) ** gamma)
if alpha >= 0:
alpha_t = alpha * targets + (1 - alpha) * (1 - targets)
loss = alpha_t * loss
return loss.mean(1).sum() / num_boxes
# Copied from transformers.models.detr.modeling_detr.DetrLoss with Detr->Yolos
class YolosLoss(nn.Module):
"""
This class computes the losses for YolosForObjectDetection/YolosForSegmentation. The process happens in two steps: 1)
we compute hungarian assignment between ground truth boxes and the outputs of the model 2) we supervise each pair
of matched ground-truth / prediction (supervise class and box).
A note on the `num_classes` argument (copied from original repo in detr.py): "the naming of the `num_classes`
parameter of the criterion is somewhat misleading. It indeed corresponds to `max_obj_id` + 1, where `max_obj_id` is
the maximum id for a class in your dataset. For example, COCO has a `max_obj_id` of 90, so we pass `num_classes` to
be 91. As another example, for a dataset that has a single class with `id` 1, you should pass `num_classes` to be 2
(`max_obj_id` + 1). For more details on this, check the following discussion
https://github.com/facebookresearch/detr/issues/108#issuecomment-650269223"
Args:
matcher (`YolosHungarianMatcher`):
Module able to compute a matching between targets and proposals.
num_classes (`int`):
Number of object categories, omitting the special no-object category.
eos_coef (`float`):
Relative classification weight applied to the no-object category.
losses (`List[str]`):
List of all the losses to be applied. See `get_loss` for a list of all available losses.
"""
def __init__(self, matcher, num_classes, eos_coef, losses):
super().__init__()
self.matcher = matcher
self.num_classes = num_classes
self.eos_coef = eos_coef
self.losses = losses
empty_weight = torch.ones(self.num_classes + 1)
empty_weight[-1] = self.eos_coef
self.register_buffer("empty_weight", empty_weight)
# removed logging parameter, which was part of the original implementation
def loss_labels(self, outputs, targets, indices, num_boxes):
"""
Classification loss (NLL) targets dicts must contain the key "class_labels" containing a tensor of dim
[nb_target_boxes]
"""
if "logits" not in outputs:
raise KeyError("No logits were found in the outputs")
source_logits = outputs["logits"]
idx = self._get_source_permutation_idx(indices)
target_classes_o = torch.cat([t["class_labels"][J] for t, (_, J) in zip(targets, indices)])
target_classes = torch.full(
source_logits.shape[:2], self.num_classes, dtype=torch.int64, device=source_logits.device
)
target_classes[idx] = target_classes_o
loss_ce = nn.functional.cross_entropy(source_logits.transpose(1, 2), target_classes, self.empty_weight)
losses = {"loss_ce": loss_ce}
return losses
@torch.no_grad()
def loss_cardinality(self, outputs, targets, indices, num_boxes):
"""
Compute the cardinality error, i.e. the absolute error in the number of predicted non-empty boxes.
This is not really a loss, it is intended for logging purposes only. It doesn't propagate gradients.
"""
logits = outputs["logits"]
device = logits.device
target_lengths = torch.as_tensor([len(v["class_labels"]) for v in targets], device=device)
# Count the number of predictions that are NOT "no-object" (which is the last class)
card_pred = (logits.argmax(-1) != logits.shape[-1] - 1).sum(1)
card_err = nn.functional.l1_loss(card_pred.float(), target_lengths.float())
losses = {"cardinality_error": card_err}
return losses
def loss_boxes(self, outputs, targets, indices, num_boxes):
"""
Compute the losses related to the bounding boxes, the L1 regression loss and the GIoU loss.
Targets dicts must contain the key "boxes" containing a tensor of dim [nb_target_boxes, 4]. The target boxes
are expected in format (center_x, center_y, w, h), normalized by the image size.
"""
if "pred_boxes" not in outputs:
raise KeyError("No predicted boxes found in outputs")
idx = self._get_source_permutation_idx(indices)
source_boxes = outputs["pred_boxes"][idx]
target_boxes = torch.cat([t["boxes"][i] for t, (_, i) in zip(targets, indices)], dim=0)
loss_bbox = nn.functional.l1_loss(source_boxes, target_boxes, reduction="none")
losses = {}
losses["loss_bbox"] = loss_bbox.sum() / num_boxes
loss_giou = 1 - torch.diag(
generalized_box_iou(center_to_corners_format(source_boxes), center_to_corners_format(target_boxes))
)
losses["loss_giou"] = loss_giou.sum() / num_boxes
return losses