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CARES: Context-Aware Resolution Selector for VLMs

Moshe Kimhi, Nimrod Shabtay, Raja Giryes, Chaim Baskin, Eli Schwartz

TL;DR

CARES introduces a lightweight, model-agnostic preprocessor that predicts the minimal sufficient input resolution for a given image–query pair, reducing token counts and compute prior to vision–language model tokenization. It uses a compact proxy VLM to extract joint image–text features from a low-resolution pass, then classifies among a discrete resolution menu and interpolates a continuous resolution at inference. Ground-truth resolutions are obtained via multi-resolution rollouts and an ANLS-based sufficiency rule, enabling efficient supervision without changing target VLMs. Across five multimodal benchmarks and multiple backbones, CARES achieves 70–85% prefill FLOPs savings with minimal to no drop in accuracy, demonstrating a practical, plug-and-play path to scalable VLM deployment. This front-end resolution control complements post-tokenization compression techniques and opens avenues for finer-grained, query-aware input allocation in multimodal systems.

Abstract

Large vision-language models (VLMs) commonly process images at native or high resolution to remain effective across tasks. This inflates visual tokens ofter to 97-99% of total tokens, resulting in high compute and latency, even when low-resolution images would suffice. We introduce \emph{CARES}-a \textbf{C}ontext-\textbf{A}ware \textbf{R}esolution \textbf{S}elector, a lightweight preprocessing module that, given an image-query pair, predicts the \emph{minimal} sufficient input resolution. CARES uses a compact VLM (350M) to extract features and predict when a target pretrained VLM's response converges to its peak ability to answer correctly. Though trained as a discrete classifier over a set of optional resolutions, CARES interpolates continuous resolutions at inference for fine-grained control. Across five multimodal benchmarks spanning documents and natural images, as well as diverse target VLMs, CARES preserves task performance while reducing compute by up to 80%.

CARES: Context-Aware Resolution Selector for VLMs

TL;DR

CARES introduces a lightweight, model-agnostic preprocessor that predicts the minimal sufficient input resolution for a given image–query pair, reducing token counts and compute prior to vision–language model tokenization. It uses a compact proxy VLM to extract joint image–text features from a low-resolution pass, then classifies among a discrete resolution menu and interpolates a continuous resolution at inference. Ground-truth resolutions are obtained via multi-resolution rollouts and an ANLS-based sufficiency rule, enabling efficient supervision without changing target VLMs. Across five multimodal benchmarks and multiple backbones, CARES achieves 70–85% prefill FLOPs savings with minimal to no drop in accuracy, demonstrating a practical, plug-and-play path to scalable VLM deployment. This front-end resolution control complements post-tokenization compression techniques and opens avenues for finer-grained, query-aware input allocation in multimodal systems.

Abstract

Large vision-language models (VLMs) commonly process images at native or high resolution to remain effective across tasks. This inflates visual tokens ofter to 97-99% of total tokens, resulting in high compute and latency, even when low-resolution images would suffice. We introduce \emph{CARES}-a \textbf{C}ontext-\textbf{A}ware \textbf{R}esolution \textbf{S}elector, a lightweight preprocessing module that, given an image-query pair, predicts the \emph{minimal} sufficient input resolution. CARES uses a compact VLM (350M) to extract features and predict when a target pretrained VLM's response converges to its peak ability to answer correctly. Though trained as a discrete classifier over a set of optional resolutions, CARES interpolates continuous resolutions at inference for fine-grained control. Across five multimodal benchmarks spanning documents and natural images, as well as diverse target VLMs, CARES preserves task performance while reducing compute by up to 80%.
Paper Structure (27 sections, 5 equations, 3 figures, 6 tables, 2 algorithms)

This paper contains 27 sections, 5 equations, 3 figures, 6 tables, 2 algorithms.

Figures (3)

  • Figure 1: Overview of CARES. Given an image and its query, CARES predicts the minimal sufficient input resolution. The image is resized accordingly and, together with the query, passed to a downstream VLM. Coarse queries are routed to lower resolution; fine-grained queries that require more detail trigger higher resolution, which yields more visual tokens in the VLM.
  • Figure 2: Accuracy vs. TTFT for DocVQA with Qwen2.5-VL-72B across native and fixed-resolution settings versus CARES. Bubble size indicates the number of pixels processed by the model.
  • Figure 3: Histogram of the predicted resolutions $\tilde{r}$ by CARES for OCRBench.