  The ability of large language models (LLMs) to process visual inputs has
given rise to general-purpose vision systems, unifying various vision-language
(VL) tasks by instruction tuning. However, due to the enormous diversity in
input-output formats in the vision domain, existing general-purpose models fail
to successfully integrate segmentation and multi-image inputs with coarse-level
tasks into a single framework. In this work, we introduce VistaLLM, a powerful
visual system that addresses coarse- and fine-grained VL tasks over single and
multiple input images using a unified framework. VistaLLM utilizes an
instruction-guided image tokenizer that filters global embeddings using task
descriptions to extract compressed and refined features from numerous images.
Moreover, VistaLLM employs a gradient-aware adaptive sampling technique to
represent binary segmentation masks as sequences, significantly improving over
previously used uniform sampling. To bolster the desired capability of
VistaLLM, we curate CoinIt, a comprehensive coarse-to-fine instruction tuning
dataset with 6.8M samples. We also address the lack of multi-image grounding
datasets by introducing a novel task, AttCoSeg (Attribute-level
Co-Segmentation), which boosts the model's reasoning and grounding capability
over multiple input images. Extensive experiments on a wide range of V- and VL
tasks demonstrate the effectiveness of VistaLLM by achieving consistent
state-of-the-art performance over strong baselines across all downstream tasks.
Our project page can be found at https://shramanpramanick.github.io/VistaLLM/.
