[Model] Add min_pixels / max_pixels to Qwen2VL as mm_processor_kwargs

[alex-jw-brooks]

FIX #9545

This PR:

• Adds support for passing min_pixels / max_pixels as mm_processor_kwargs for Qwen2VL
• Updates the single image to show usage of min_pixels / max_pixels

Example usage for reference (mm_processor_kwargs can be passed at init time or inference time):

from vllm import LLM, SamplingParams
from vllm.assets.image import ImageAsset

image = ImageAsset("cherry_blossom").pil_image.convert("RGB")
prompt = ("<|im_start|>system\nYou are a helpful assistant.<|im_end|>\n"
            "<|im_start|>user\n<|vision_start|><|image_pad|><|vision_end|>"
            "Can you describe this image?<|im_end|>\n"
            "<|im_start|>assistant\n")

llm = LLM(
    model="Qwen/Qwen2-VL-2B-Instruct",
    max_num_seqs=5,
)

sampling_params = SamplingParams(temperature=0.2, max_tokens=64)

outputs = llm.generate(
    {
        "prompt": prompt,
        "multi_modal_data": {"image": image},
        "mm_processor_kwargs": {"min_pixels": 64 * 64 * 3, "max_pixels": 512 * 512 * 3},

    }, 
    sampling_params=sampling_params
)

for o in outputs:
    generated_text = o.outputs[0].text
    print(generated_text)

sample output

The image depicts a beautiful scene featuring a tall tower with a distinctive cylindrical shape, set against a clear blue sky. The tower appears to be a modern architectural structure, possibly a telecommunications or observation tower, given its height and design. The tower is surrounded by a dense canopy of cherry blossom trees, which are in full bloom

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[alex-jw-brooks]

Should this be enforced on actual requests also? I'm a bit confused why there are bounds on these values only while getting the max mm tokens, since it means actual requests can exceed the max like in one of the tests I added 🤔

[DarkLight1337]

Should this be enforced on actual requests also?

You mean requests coming in from online inference? Probably not, since this is model specific.

[alex-jw-brooks]

Not generically, I mostly meant in the input processor and multimodal mappers for this class. It seemed a bit weird to only use an upper bound on max_pixels in the max calculation, but not apply the same restriction in places like this, because it makes the max token per image count wrong

[DarkLight1337]

Ah I see. @fyabc can you comment on this?

[DarkLight1337]

Let's still merge this PR first as this issue is already present in the existing code, so we can fix this in a separate PR.

[DarkLight1337]

Overall LGTM!