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# Copyright 2024 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 PaliGemmamodel."""
from collections.abc import Callable
from dataclasses import dataclass
import torch
from torch import nn
from ...cache_utils import Cache
from ...configuration_utils import PreTrainedConfig
from ...generation import GenerationMixin
from ...masking_utils import create_masks_for_generate
from ...modeling_flash_attention_utils import FlashAttentionKwargs
from ...modeling_outputs import BaseModelOutputWithPast, BaseModelOutputWithPooling
from ...modeling_utils import PreTrainedModel
from ...processing_utils import Unpack
from ...utils import (
ModelOutput,
TransformersKwargs,
auto_docstring,
can_return_tuple,
logging,
torch_compilable_check,
)
from ..auto import AutoModel
from .configuration_paligemma import PaliGemmaConfig
logger = logging.get_logger(__name__)
@dataclass
@auto_docstring(
custom_intro="""
Base class for Paligemma outputs, with hidden states and attentions.
"""
)
class PaligemmaModelOutputWithPast(BaseModelOutputWithPast):
r"""
image_hidden_states (`torch.FloatTensor`, *optional*):
A `torch.FloatTensor` of size `(batch_size, num_images, sequence_length, hidden_size)`.
image_hidden_states of the model produced by the vision encoder and after projecting the last hidden state.
"""
image_hidden_states: torch.FloatTensor | None = None
@dataclass
@auto_docstring(
custom_intro="""
Base class for PaliGemma causal language model (or autoregressive) outputs.
"""
)
class PaliGemmaCausalLMOutputWithPast(ModelOutput):
r"""
loss (`torch.FloatTensor` of shape `(1,)`, *optional*, returned when `labels` is provided):
Language modeling loss (for next-token prediction).
logits (`torch.FloatTensor` of shape `(batch_size, sequence_length, config.text_config.vocab_size)`):
Prediction scores of the language modeling head (scores for each vocabulary token before SoftMax).
past_key_values (`Cache`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
It is a [`~cache_utils.Cache`] instance. For more details, see our [kv cache guide](https://huggingface.co/docs/transformers/en/kv_cache).
Contains pre-computed hidden-states (key and values in the self-attention blocks) that can be used (see
`past_key_values` input) to speed up sequential decoding.
image_hidden_states (`torch.FloatTensor`, *optional*):
A `torch.FloatTensor` of size `(batch_size, num_images, sequence_length, hidden_size)`.
image_hidden_states of the model produced by the vision encoder after projecting last hidden state.
"""
loss: torch.FloatTensor | None = None
logits: torch.FloatTensor | None = None
past_key_values: Cache | None = None
hidden_states: tuple[torch.FloatTensor] | None = None
attentions: tuple[torch.FloatTensor] | None = None
image_hidden_states: torch.FloatTensor | None = None
class PaliGemmaMultiModalProjector(nn.Module):
def __init__(self, config: PaliGemmaConfig):
super().__init__()
self.linear = nn.Linear(config.vision_config.hidden_size, config.vision_config.projection_dim, bias=True)
def forward(self, image_features):
hidden_states = self.linear(image_features)
return hidden_states
def token_type_ids_mask_function(
token_type_ids: torch.Tensor | None,
image_group_ids: torch.Tensor | None,
) -> Callable | None:
"""
This function adds the correct offsets to the `q_idx` and `kv_idx` as the torch API can only accept lengths,
not start and end indices.
"""
# Do not return an additional mask in this case
if token_type_ids is None:
return None
def inner_mask(batch_idx: int, head_idx: int, q_idx: int, kv_idx: int) -> bool:
# If it's 1 for both query and key/value, we are in an image block
# NOTE: static cache shape goes beyond input seq length, while token_type_ids.shape[1] == input seq length
# Since vmap doesn't support `if statement` we workaround it with `torch.where`
safe_q_idx = torch.where(q_idx < token_type_ids.shape[1], q_idx, 0)
safe_kv_idx = torch.where(kv_idx < token_type_ids.shape[1], kv_idx, 0)
token_type_ids_at_q_idx = token_type_ids[batch_idx, safe_q_idx]
token_type_ids_at_q_idx = torch.where(q_idx < token_type_ids.shape[1], token_type_ids_at_q_idx, 0)
token_type_ids_at_kv_idx = token_type_ids[batch_idx, safe_kv_idx]
token_type_ids_at_kv_idx = torch.where(kv_idx < token_type_ids.shape[1], token_type_ids_at_kv_idx, 0)
image_group_ids_at_q_idx = image_group_ids[batch_idx, safe_q_idx]
image_group_ids_at_q_idx = torch.where(q_idx < image_group_ids.shape[1], image_group_ids_at_q_idx, -1)
image_group_ids_at_kv_idx = image_group_ids[batch_idx, safe_kv_idx]
image_group_ids_at_kv_idx = torch.where(kv_idx < image_group_ids.shape[1], image_group_ids_at_kv_idx, -1)
is_image_block = (token_type_ids_at_q_idx == 1) & (token_type_ids_at_kv_idx == 1)
same_image_block = image_group_ids_at_q_idx == image_group_ids_at_kv_idx
# This is bidirectional attention whenever we are dealing with image tokens
return is_image_block & same_image_block
return inner_mask
def create_causal_mask_mapping(
config: PreTrainedConfig,
input_embeds: torch.Tensor,
attention_mask: torch.Tensor | None,
cache_position: torch.Tensor,
past_key_values: Cache | None,
position_ids: torch.Tensor | None,
token_type_ids: torch.Tensor | None = None,
pixel_values: torch.FloatTensor | None = None,
is_training: bool | None = False,
is_first_iteration: bool | None = None,
**kwargs,
) -> dict:
"""
Overwrites the base `create_masks_for_generate` with `token_type_ids` masking to create the causal mask mapping
for all kinds of forward passes. Paligemma uses a bidirectional mask on the prompt tokens.
Uses `pixel_values` as an optional input to disambiguate edge cases.
"""
if is_training and token_type_ids is None:
raise ValueError("`token_type_ids` is required as a model input when training")
mask_kwargs = {
"config": config.get_text_config(),
"input_embeds": input_embeds,
"attention_mask": attention_mask,
"cache_position": cache_position,
"past_key_values": past_key_values,
"position_ids": position_ids,
}
# Infer if prefill or decoding stage, if the flag isn't passed. This happens only when the mask is constructed
# from `forward` call. If users run a `forward` call, we have no option to infer `is_first_iteration` because users may be
# running generation with custom loop. Thus we need to infer it in a `non-perfect` way
# NOTE: Determining prefill in that case requires checking data values, which is not compile-compatible.
is_first_iteration = (
is_first_iteration
if is_first_iteration
else (past_key_values is None or not past_key_values.is_initialized or pixel_values is not None)
)
if is_first_iteration or not kwargs.get("use_cache", True):
if token_type_ids is not None:
# The logic bellow was originally written for Gemma3, where `token_type_ids` is reversed. Let's reverse
# it to then use exactly the same logic.
token_type_ids = 1 - token_type_ids
else:
logger.warning_once(
"It is a prefill stage but The `token_type_ids` is not provided. We recommend "
"passing `token_type_ids` to the model to prevent bad attention masking."
)
# NOTE: this branch can't be reached when training because `token_type_ids` is required as a model input.
token_type_ids = torch.ones_like(input_embeds)[:, :, 0]
# Logic originally copied from Gemma3. It holds up for Paligemma as well because Paligemma assumes up to one image
# per prompt AND we reverse `token_type_ids` above. Gemma3 uses a bidirectional mask for images, tagged through
# `token_type_ids` 1s.
if token_type_ids is not None and is_first_iteration:
# We need to pass an additional mask function to account for token type ids, and it needs to be an `or` (to
# undo the causal masking)
# First find where a new image block starts: 1 if image and previous not image
# The images cannot attend to future images, but can attend to all prev images and to itself bidirectionally
is_image = (token_type_ids == 1).to(cache_position.device)
is_previous_image = nn.functional.pad(is_image, (1, 0), value=0)[:, :-1]
new_image_start = is_image & ~is_previous_image
image_group_ids = torch.cumsum(new_image_start.int(), dim=1) - 1
image_group_ids = torch.where(is_image, image_group_ids, torch.full_like(token_type_ids, -1))
mask_kwargs["or_mask_function"] = token_type_ids_mask_function(
token_type_ids.to(cache_position.device), image_group_ids
)
return create_masks_for_generate(**mask_kwargs)
@auto_docstring
class PaliGemmaPreTrainedModel(PreTrainedModel):
config: PaliGemmaConfig
base_model_prefix = "model"
input_modalities = ("image", "text")
supports_gradient_checkpointing = True
_no_split_modules = ["PaliGemmaMultiModalProjector"]
_skip_keys_device_placement = "past_key_values"
_can_compile_fullgraph = False
_supports_flash_attn = True
_supports_sdpa = True
_supports_flex_attn = True
_supports_attention_backend = True
@auto_docstring(
custom_intro="""
The Base Paligemma model which consists of a vision backbone and a language model without language modeling head.,
"""
)
class PaliGemmaModel(PaliGemmaPreTrainedModel):
_checkpoint_conversion_mapping = {"language_model.model": "language_model"}
# we are filtering the logits/labels so we shouldn't divide the loss based on num_items_in_batch
accepts_loss_kwargs = False
def __init__(self, config: PaliGemmaConfig):
super().__init__(config)
self.vision_tower = AutoModel.from_config(config=config.vision_config)
self.multi_modal_projector = PaliGemmaMultiModalProjector(config)
self.vocab_size = config.text_config.vocab_size
language_model = AutoModel.from_config(config=config.text_config)
self.language_model = language_model
self.text_config_dtype = self.config.get_text_config().dtype or self.dtype
self.post_init()
# Copied from transformers.models.llava.modeling_llava.LlavaModel.get_input_embeddings with Llava->PaliGemma
def get_input_embeddings(self):
return self.language_model.get_input_embeddings()
# Copied from transformers.models.llava.modeling_llava.LlavaModel.set_input_embeddings with Llava->PaliGemma
def set_input_embeddings(self, value):
self.language_model.set_input_embeddings(value)
@can_return_tuple
@auto_docstring(
custom_intro="Obtains image last hidden states from the vision tower and apply multimodal projection."
)
def get_image_features(
self, pixel_values: torch.FloatTensor, **kwargs: Unpack[TransformersKwargs]
) -> tuple | BaseModelOutputWithPooling:
image_outputs = self.vision_tower(pixel_values, return_dict=True, **kwargs)
selected_image_feature = image_outputs.last_hidden_state
image_features = self.multi_modal_projector(selected_image_feature)
image_features = image_features / (self.config.text_config.hidden_size**0.5)
image_outputs.pooler_output = image_features
return image_outputs
def get_placeholder_mask(
self, input_ids: torch.LongTensor, inputs_embeds: torch.FloatTensor, image_features: torch.FloatTensor
):
"""
Obtains multimodal placeholder mask from `input_ids` or `inputs_embeds`, and checks that the placeholder token count is
equal to the length of multimodal features. If the lengths are different, an error is raised.
"""
if input_ids is None:
special_image_mask = inputs_embeds == self.get_input_embeddings()(
torch.tensor(self.config.image_token_id, dtype=torch.long, device=inputs_embeds.device)
)
special_image_mask = special_image_mask.all(-1)
else:
special_image_mask = input_ids == self.config.image_token_id
n_image_tokens = special_image_mask.sum()
n_image_features = image_features.shape[0] * image_features.shape[1]
special_image_mask = special_image_mask.unsqueeze(-1).expand_as(inputs_embeds).to(inputs_embeds.device)
torch_compilable_check(
inputs_embeds[special_image_mask].numel() == image_features.numel(),
f"Image features and image tokens do not match, tokens: {n_image_tokens}, features: {n_image_features}",
)
return special_image_mask
@can_return_tuple
@auto_docstring
def forward(
self,
input_ids: torch.LongTensor | None = None,
pixel_values: torch.FloatTensor | None = None,
attention_mask: torch.Tensor | None = None,
position_ids: torch.LongTensor | None = None,
past_key_values: Cache | None = None,
token_type_ids: torch.LongTensor | None = None,
cache_position: torch.LongTensor | None = None,
inputs_embeds: torch.FloatTensor | None = None,
labels: torch.LongTensor | None = None,
use_cache: bool | None = None,
output_attentions: bool | None = None,
output_hidden_states: bool | None = None,
return_dict: bool | None = None,
**kwargs: Unpack[FlashAttentionKwargs],
) -> tuple | PaligemmaModelOutputWithPast:
r"""
labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
config.text_config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
(masked), the loss is only computed for the tokens with labels in `[0, ..., config.text_config.vocab_size]`.
Example:
```python
>>> from PIL import Image
>>> import httpx
>>> from io import BytesIO
>>> from transformers import AutoProcessor, PaliGemmaForConditionalGeneration
>>> model = PaliGemmaForConditionalGeneration.from_pretrained("google/paligemma2-3b-mix-224")
>>> processor = AutoProcessor.from_pretrained("google/paligemma2-3b-mix-224")
>>> prompt = "Where is the cat standing?"
>>> url = "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/pipeline-cat-chonk.jpeg"
>>> with httpx.stream("GET", url) as response:
... image = Image.open(BytesIO(response.read()))
>>> inputs = processor(images=image, text=prompt, return_tensors="pt")
>>> # Generate
>>> generate_ids = model.generate(**inputs,)
>>> processor.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
"Where is the cat standing?\nsnow"
```"""
if (input_ids is None) ^ (inputs_embeds is not None):
raise ValueError("You must specify exactly one of input_ids or inputs_embeds")
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
# Replace image id with PAD if the image token if OOV, to avoid index-errors
if input_ids is not None and self.config.image_token_id >= self.vocab_size:
special_image_mask = input_ids == self.config.image_token_id
llm_input_ids = input_ids.clone()
llm_input_ids[special_image_mask] = 0
else:
llm_input_ids = input_ids
if inputs_embeds is None:
inputs_embeds = self.get_input_embeddings()(llm_input_ids)
if cache_position is None:
past_seen_tokens = past_key_values.get_seq_length() if past_key_values is not None else 0
cache_position = torch.arange(
past_seen_tokens, past_seen_tokens + inputs_embeds.shape[1], device=inputs_embeds.device
)
if position_ids is None:
position_ids = cache_position.unsqueeze(0) + 1 # Paligemma positions are 1-indexed
# Merge text and images
if pixel_values is not None:
image_features = self.get_image_features(pixel_values, return_dict=True).pooler_output
image_features = image_features.to(inputs_embeds.device, inputs_embeds.dtype)
special_image_mask = self.get_placeholder_mask(
input_ids, inputs_embeds=inputs_embeds, image_features=image_features
)
inputs_embeds = inputs_embeds.masked_scatter(special_image_mask, image_features)
# It may already have been prepared by e.g. `generate`
if not isinstance(causal_mask_mapping := attention_mask, dict):
causal_mask_mapping = create_causal_mask_mapping(
self.config,
inputs_embeds,
attention_mask,
cache_position,
past_key_values,
position_ids,
token_type_ids,
pixel_values,
is_training=self.training,
)
outputs = self.language_model(
attention_mask=causal_mask_mapping,
position_ids=position_ids,
past_key_values=past_key_values,
inputs_embeds=inputs_embeds,
use_cache=use_cache,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
return_dict=True,
cache_position=cache_position,
**kwargs,
)
return PaligemmaModelOutputWithPast(
last_hidden_state=outputs.last_hidden_state,
past_key_values=outputs.past_key_values,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
image_hidden_states=image_features if pixel_values is not None else None,
)
@auto_docstring(
custom_intro="""
The Base Paligemma model which consists of a vision backbone and a language model without language modeling head.,
"""
)
class PaliGemmaForConditionalGeneration(PaliGemmaPreTrainedModel, GenerationMixin):
_checkpoint_conversion_mapping = {
"^language_model.model": "model.language_model",
"^vision_tower": "model.vision_tower",
"^multi_modal_projector": "model.multi_modal_projector",
"^language_model.lm_head": "lm_head",
}
_tied_weights_keys = {"lm_head.weight": "model.language_model.embed_tokens.weight"}
def __init__(self, config: PaliGemmaConfig):
super().__init__(config)
self.model = PaliGemmaModel(config)
self.lm_head = nn.Linear(config.text_config.hidden_size, config.text_config.vocab_size, bias=False)
self.post_init()
def get_input_embeddings(self):
return self.model.get_input_embeddings()
def set_input_embeddings(self, value):
self.model.set_input_embeddings(value)
@auto_docstring
def get_image_features(self, pixel_values: torch.FloatTensor, **kwargs: Unpack[TransformersKwargs]):
return self.model.get_image_features(pixel_values, **kwargs)
@can_return_tuple
@auto_docstring
def forward(
self,
input_ids: torch.LongTensor | None = None,
pixel_values: torch.FloatTensor | None = None,
attention_mask: torch.Tensor | None = None,
position_ids: torch.LongTensor | None = None,
past_key_values: Cache | None = None,
token_type_ids: torch.LongTensor | None = None,
cache_position: torch.LongTensor | None = None,
inputs_embeds: torch.FloatTensor | None = None,
labels: torch.LongTensor | None = None,
use_cache: bool | None = None,
output_attentions: bool | None = None,
output_hidden_states: bool | None = None,
return_dict: bool | None = None,
logits_to_keep: int | torch.Tensor = 0,
**kwargs: Unpack[TransformersKwargs],
) -> tuple | PaliGemmaCausalLMOutputWithPast:
r"""
labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
config.text_config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
(masked), the loss is only computed for the tokens with labels in `[0, ..., config.text_config.vocab_size]`.
Example:
```python
>>> from PIL import Image
>>> import httpx
>>> from io import BytesIO
>>> from transformers import AutoProcessor, PaliGemmaForConditionalGeneration
>>> model = PaliGemmaForConditionalGeneration.from_pretrained("google/paligemma2-3b-mix-224")
>>> processor = AutoProcessor.from_pretrained("google/paligemma2-3b-mix-224")
>>> prompt = "Where is the cat standing?"
>>> url = "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/pipeline-cat-chonk.jpeg"
>>> with httpx.stream("GET", url) as response:
... image = Image.open(BytesIO(response.read()))
>>> inputs = processor(images=image, text=prompt, return_tensors="pt")
>>> # Generate
>>> generate_ids = model.generate(**inputs,)
>>> processor.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
"Where is the cat standing?\nsnow"
```"""
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
outputs = self.model(
input_ids=input_ids,
pixel_values=pixel_values,
token_type_ids=token_type_ids,
attention_mask=attention_mask,
position_ids=position_ids,
past_key_values=past_key_values,
inputs_embeds=inputs_embeds,
use_cache=use_cache,
labels=labels,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
return_dict=True,
cache_position=cache_position,
**kwargs,
)
hidden_states = outputs[0]
# Only compute necessary logits, and do not upcast them to float if we are not computing the loss
slice_indices = slice(-logits_to_keep, None) if isinstance(logits_to_keep, int) else logits_to_keep
logits = self.lm_head(hidden_states[:, slice_indices, :])
loss = None
if labels is not None:
loss = self.loss_function(
logits=logits, labels=labels, vocab_size=self.config.text_config.vocab_size, **kwargs
)
return PaliGemmaCausalLMOutputWithPast(
loss=loss,
logits=logits,
past_key_values=outputs.past_key_values,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
image_hidden_states=outputs.image_hidden_states,
)
def prepare_inputs_for_generation(
self,
input_ids,
past_key_values=None,
inputs_embeds=None,
cache_position=None,
position_ids=None,
pixel_values=None,
attention_mask=None,
token_type_ids=None,
use_cache=True,
logits_to_keep=None,
labels=None,
is_first_iteration=False,
**kwargs,
):
# Overwritten -- custom `position_ids` and `pixel_values` handling
model_inputs = super().prepare_inputs_for_generation(
input_ids,
past_key_values=past_key_values,
inputs_embeds=inputs_embeds,
attention_mask=attention_mask,
position_ids=position_ids,
cache_position=cache_position,
use_cache=use_cache,
logits_to_keep=logits_to_keep,
token_type_ids=token_type_ids,
is_first_iteration=is_first_iteration,
**kwargs,
)
# position_ids in Paligemma are 1-indexed
if model_inputs.get("position_ids") is not None:
model_inputs["position_ids"] += 1
# Pixel values are used only in the first iteration if available
# In subsquent iterations, they are already merged with text and cached
# NOTE: first iteration doesn't have to be prefill, it can be the first
# iteration with a question and cached system prompt (continue generate from cache). NOTE: use_cache=False needs pixel_values always
if is_first_iteration or not use_cache:
model_inputs["pixel_values"] = pixel_values
return model_inputs
@staticmethod
def create_masks_for_generate(
config: PreTrainedConfig,
input_embeds: torch.Tensor,
attention_mask: torch.Tensor | None,
cache_position: torch.Tensor,
past_key_values: Cache | None,
position_ids: torch.Tensor | None,
token_type_ids: torch.Tensor | None = None,
is_first_iteration: bool | None = False,
**kwargs,
) -> dict:
# Uses the overwritten `create_masks_for_generate` with `token_type_ids` masking
return create_causal_mask_mapping(
config,
input_embeds,
attention_mask,
cache_position,
past_key_values,
position_ids,
token_type_ids,
is_first_iteration=is_first_iteration,
**{k: v for k, v in kwargs.items() if k != "pixel_values"},
)
__all__ = ["PaliGemmaForConditionalGeneration", "PaliGemmaPreTrainedModel", "PaliGemmaModel"]