cohere2_vision.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
# Adapted from vllm/model_executor/models/aya_vision.py
"""Command-A-Vision (Cohere2Vision) multimodal model implementation for vLLM."""

from collections.abc import Iterable, Mapping, Sequence
from typing import Annotated, Literal

import torch
from torch import nn
from transformers import BatchFeature, PretrainedConfig
from transformers.models.cohere2_vision import Cohere2VisionConfig
from transformers.models.cohere2_vision.image_processing_cohere2_vision_fast import (  # noqa: E501
    Cohere2VisionImageProcessorFast,
)
from transformers.models.cohere2_vision.processing_cohere2_vision import (
    Cohere2VisionProcessor,
)

from vllm.config import VllmConfig
from vllm.config.multimodal import BaseDummyOptions
from vllm.inputs import MultiModalDataDict
from vllm.model_executor.layers.activation import MulAndSilu
from vllm.model_executor.layers.linear import (
    MergedColumnParallelLinear,
    RowParallelLinear,
)
from vllm.model_executor.layers.quantization import QuantizationConfig
from vllm.model_executor.layers.quantization.awq import AWQConfig
from vllm.multimodal import MULTIMODAL_REGISTRY
from vllm.multimodal.inputs import (
    MultiModalFieldConfig,
    MultiModalKwargsItems,
)
from vllm.multimodal.parse import ImageProcessorItems, ImageSize, MultiModalDataItems
from vllm.multimodal.processing import (
    BaseDummyInputsBuilder,
    BaseMultiModalProcessor,
    BaseProcessingInfo,
    PromptReplacement,
    PromptUpdate,
    PromptUpdateDetails,
)
from vllm.sequence import IntermediateTensors
from vllm.utils.tensor_schema import TensorSchema, TensorShape

from .interfaces import MultiModalEmbeddings, SupportsMultiModal, SupportsPP
from .siglip import SiglipVisionModel
from .utils import (
    AutoWeightsLoader,
    WeightsMapper,
    init_vllm_registered_model,
    maybe_prefix,
)


class Cohere2VisionImagePixelInputs(TensorSchema):
    """
    Dimensions:
        - np: The total number of patches over each image over each prompt in
              the batch
        - c: Number of channels
        - h: Height of each image patch
        - w: Width of each image patch
        - bn: Batch size * number of images
    """

    type: Literal["pixel_values"]

    pixel_values: Annotated[
        torch.Tensor,
        TensorShape("np", 3, "h", "w"),
    ]

    num_patches: Annotated[
        torch.Tensor,
        TensorShape("bn"),
    ]


class Cohere2VisionMultiModalProjector(nn.Module):
    """Multimodal projector that maps vision features to text embedding space.

    Uses pixel shuffle downsampling followed by SwiGLU activation.
    """

    def __init__(self, config: Cohere2VisionConfig, prefix: str = ""):
        super().__init__()
        self.downsample_factor = config.downsample_factor

        # Input dimension after pixel shuffle downsampling
        input_dim = config.vision_config.hidden_size * (config.downsample_factor**2)
        # MergedColumnParallelLinear expects the intermediate size to be a list
        # of sizes, so that it will load the weights as two separate linear
        # layers before applying any parallelism.
        # We need to divide the alignment intermediate size by 2 because
        # the weights are merged weights of two linear layers for SwiGLU.
        self.intermediate_size = config.alignment_intermediate_size // 2

        self.linear_1 = MergedColumnParallelLinear(
            input_dim,
            [self.intermediate_size] * 2,
            bias=True,
            return_bias=False,
            prefix=f"{prefix}.linear_1",
        )
        self.act = MulAndSilu()
        self.linear_2 = RowParallelLinear(
            self.intermediate_size,
            config.text_config.hidden_size,
            bias=True,
            return_bias=False,
            prefix=f"{prefix}.linear_2",
        )

    def forward(self, image_features):
        image_features = self.pixel_shuffle(image_features)
        hidden_states = self.linear_1(image_features)
        hidden_states = self.act(hidden_states)
        hidden_states = self.linear_2(hidden_states)
        return hidden_states

    def pixel_shuffle(self, image_features: torch.Tensor) -> torch.Tensor:
        """Apply pixel shuffle downsampling to reduce spatial dimensions.

        Args:
            image_features: Input tensor of shape [B, S, D] where S = H*W

        Returns:
            Downsampled tensor with increased channel dimension
        """
        height = width = int(image_features.shape[1] ** 0.5)
        x = image_features.reshape(image_features.shape[0], width, height, -1)
        n, h, w, c = x.size()
        scale_factor = 1.0 / self.downsample_factor
        nh = int(h * scale_factor)
        nw = int(w * scale_factor)
        x = x.reshape(n, nh, self.downsample_factor, nw, self.downsample_factor, c)
        x = x.permute(0, 1, 3, 2, 4, 5).contiguous()
        x = x.reshape(n, nh, nw, -1)
        return x


class Cohere2VisionProcessingInfo(BaseProcessingInfo):
    def get_hf_config(self) -> Cohere2VisionConfig:
        return self.ctx.get_hf_config(Cohere2VisionConfig)

    def get_hf_processor(self, **kwargs: object) -> Cohere2VisionProcessor:
        return self.ctx.get_hf_processor(Cohere2VisionProcessor, **kwargs)

    def get_image_processor(self, **kwargs: object):
        return self.get_hf_processor(**kwargs).image_processor

    def get_supported_mm_limits(self) -> Mapping[str, int | None]:
        return {"image": None}

    def get_image_size_with_most_features(self) -> ImageSize:
        image_processor = self.get_image_processor()
        height = image_processor.size["height"]
        width = image_processor.size["width"]
        max_patches = image_processor.max_patches
        return ImageSize(height=height * max_patches, width=width)

    def get_num_patches(
        self,
        *,
        image_width: int,
        image_height: int,
        processor: Cohere2VisionProcessor,
        mm_kwargs: Mapping[str, object],
    ) -> int:
        """
        Calculate the number of image patches for a given image.
        Uses the HF processor to determine the actual number of patches.
        """
        image_processor: Cohere2VisionImageProcessorFast = processor.image_processor

        return image_processor.get_number_of_image_patches(
            image_height,
            image_width,
            self.ctx.get_merged_mm_kwargs(mm_kwargs),
        )


class Cohere2VisionDummyInputsBuilder(
    BaseDummyInputsBuilder[Cohere2VisionProcessingInfo]
):
    def get_dummy_text(self, mm_counts: Mapping[str, int]) -> str:
        num_images = mm_counts.get("image", 0)

        processor = self.info.get_hf_processor()
        image_token = processor.image_token

        return image_token * num_images

    def get_dummy_mm_data(
        self,
        seq_len: int,
        mm_counts: Mapping[str, int],
        mm_options: Mapping[str, BaseDummyOptions],
    ) -> MultiModalDataDict:
        num_images = mm_counts.get("image", 0)
        image_size = self.info.get_image_size_with_most_features()

        image_overrides = mm_options.get("image")

        return {
            "image": self._get_dummy_images(
                width=image_size.width,
                height=image_size.height,
                num_images=num_images,
                overrides=image_overrides,
            )
        }


class Cohere2VisionMultiModalProcessor(
    BaseMultiModalProcessor[Cohere2VisionProcessingInfo]
):
    def _call_hf_processor(
        self,
        prompt: str,
        mm_data: Mapping[str, object],
        mm_kwargs: Mapping[str, object],
        tok_kwargs: Mapping[str, object],
    ) -> BatchFeature:
        processed_outputs = super()._call_hf_processor(
            prompt,
            mm_data,
            mm_kwargs,
            tok_kwargs,
        )

        # Ensure num_patches is available for proper tensor splitting
        if (
            "num_patches" not in processed_outputs
            and (images := mm_data.get("images")) is not None
        ):
            hf_processor = self.info.get_hf_processor(**mm_kwargs)

            # Fallback calculation if HF processor didn't provide num_patches
            mm_items = self.info.parse_mm_data({"image": images}, validate=False)
            parsed_images = mm_items.get_items("image", ImageProcessorItems)

            num_patches = [
                self.info.get_num_patches(
                    image_width=parsed_images.get_image_size(i).width,
                    image_height=parsed_images.get_image_size(i).height,
                    processor=hf_processor,
                    mm_kwargs=mm_kwargs,
                )
                for i in range(len(parsed_images))
            ]
            processed_outputs["num_patches"] = torch.tensor(num_patches)

        return processed_outputs

    def _get_mm_fields_config(
        self,
        hf_inputs: BatchFeature,
        hf_processor_mm_kwargs: Mapping[str, object],
    ) -> Mapping[str, MultiModalFieldConfig]:
        num_patches = hf_inputs.get("num_patches", torch.empty(0))
        return dict(
            pixel_values=MultiModalFieldConfig.flat_from_sizes("image", num_patches),
            num_patches=MultiModalFieldConfig.batched("image"),
            image_embeds=MultiModalFieldConfig.batched("image"),
        )

    def _get_prompt_updates(
        self,
        mm_items: MultiModalDataItems,
        hf_processor_mm_kwargs: Mapping[str, object],
        out_mm_kwargs: MultiModalKwargsItems,
    ) -> Sequence[PromptUpdate]:
        hf_processor = self.info.get_hf_processor(**hf_processor_mm_kwargs)
        image_token = hf_processor.image_token
        img_tokens_per_tile = int(hf_processor.patch_size**2)
        img_line_break_token = hf_processor.img_line_break_token
        boi_token = hf_processor.boi_token
        eoi_token = hf_processor.eoi_token

        def get_replacement(item_idx: int):
            images = mm_items.get_items("image", ImageProcessorItems)
            image_size: ImageSize = images.get_image_size(item_idx)

            num_patches = self.info.get_num_patches(
                image_width=image_size.width,
                image_height=image_size.height,
                processor=hf_processor,
                mm_kwargs=hf_processor_mm_kwargs,
            )
            patch_tokens = image_token * img_tokens_per_tile + img_line_break_token
            repl = f"{boi_token}{patch_tokens * num_patches}{eoi_token}"

            return PromptUpdateDetails.select_text(repl, image_token)

        return [
            PromptReplacement(
                modality="image",
                target=image_token,
                replacement=get_replacement,
            )
        ]


@MULTIMODAL_REGISTRY.register_processor(
    Cohere2VisionMultiModalProcessor,
    info=Cohere2VisionProcessingInfo,
    dummy_inputs=Cohere2VisionDummyInputsBuilder,
)
class Cohere2VisionForConditionalGeneration(nn.Module, SupportsMultiModal, SupportsPP):
    hf_to_vllm_mapper = WeightsMapper(
        orig_to_new_prefix={
            "model.vision_tower.": "vision_tower.",
            "model.multi_modal_projector.": "multi_modal_projector.",
            "model.language_model.": "language_model.model.",
            "lm_head.": "language_model.lm_head.",
        }
    )

    def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
        super().__init__()
        config: Cohere2VisionConfig = vllm_config.model_config.hf_config
        quant_config = vllm_config.quant_config
        multimodal_config = vllm_config.model_config.multimodal_config
        self.config = config
        self.quant_config = quant_config
        self.multimodal_config = multimodal_config
        self._patch_quant_config(config, quant_config)

        with self._mark_tower_model(vllm_config, "image"):
            self.vision_tower = SiglipVisionModel(
                config.vision_config,
                quant_config,
                prefix=maybe_prefix(prefix, "vision_tower"),
            )
            self.multi_modal_projector = Cohere2VisionMultiModalProjector(
                config, prefix=maybe_prefix(prefix, "multi_modal_projector")
            )

        with self._mark_language_model(vllm_config):
            self.language_model = init_vllm_registered_model(
                vllm_config=vllm_config,
                hf_config=config.text_config,
                prefix=maybe_prefix(prefix, "language_model"),
                architectures=config.text_config.architectures,
            )

    @property
    def dtype(self):
        return next(self.parameters()).dtype

    def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]) -> set[str]:
        loader = AutoWeightsLoader(self)
        return loader.load_weights(weights, mapper=self.hf_to_vllm_mapper)

    def _process_image_input(
        self, image_input: Cohere2VisionImagePixelInputs, **kwargs
    ) -> list[torch.Tensor]:
        """Process image pixels through vision tower and projector.

        Args:
            image_input: Validated image input containing pixel values and
                         patch counts

        Returns:
            List of flattened image embeddings, one per image
        """
        pixel_values = image_input["pixel_values"]
        num_patches = image_input["num_patches"]

        # Extract visual features
        image_features = self.vision_tower(pixel_values)

        # Project to text embedding space
        image_embeds = self.multi_modal_projector(image_features)

        # Split and flatten embeddings per image
        return [e.flatten(0, 2) for e in image_embeds.split(num_patches.tolist())]

    def _parse_and_validate_image_input(
        self, **kwargs: object
    ) -> Cohere2VisionImagePixelInputs | None:
        pixel_values = kwargs.pop("pixel_values", None)
        num_patches = kwargs.pop("num_patches", None)
        image_embeds = kwargs.pop("image_embeds", None)
        assert image_embeds is None, "Cohere2Vision does not support image_embeds."

        if pixel_values is None:
            return None

        return Cohere2VisionImagePixelInputs(
            type="pixel_values",
            pixel_values=pixel_values,
            num_patches=num_patches,
            resolve_bindings={
                "h": self.config.vision_config.image_size,
                "w": self.config.vision_config.image_size,
            },
        )

    def _patch_quant_config(
        self, config: PretrainedConfig, quant_config: QuantizationConfig
    ):
        # the awq models from OpenGVLab missing `modules_to_not_convert`
        # patch the quant_config to add `modules_to_not_convert` back
        if isinstance(quant_config, AWQConfig):
            text_config = config.text_config
            llm_quant_config = getattr(text_config, "quantization_config", None)
            if (not quant_config.modules_to_not_convert) and (
                llm_quant_config is not None
            ):
                quant_config.modules_to_not_convert.append("vision_tower")

    def embed_multimodal(self, **kwargs: object) -> MultiModalEmbeddings:
        image_input = self._parse_and_validate_image_input(**kwargs)
        if image_input is None:
            return []

        return self._process_image_input(image_input, **kwargs)

    def forward(
        self,
        input_ids: torch.Tensor | None,
        positions: torch.Tensor,
        intermediate_tensors: IntermediateTensors | None = None,
        inputs_embeds: torch.Tensor | None = None,
        **kwargs: object,
    ) -> torch.Tensor | IntermediateTensors:
        if intermediate_tensors is not None:
            inputs_embeds = None

        hidden_states = self.language_model.model(
            input_ids=input_ids,
            positions=positions,
            intermediate_tensors=intermediate_tensors,
            inputs_embeds=inputs_embeds,
        )
        return hidden_states

    def compute_logits(
        self,
        hidden_states: torch.Tensor,
    ) -> torch.Tensor | None:
        return self.language_model.compute_logits(hidden_states)