High-density LED arrays enable high-speed transmission in image sensor-based visible light communication (VLC) systems. However, when optical spots become blurred and spatially overlapped due to focal shift, resolution limitations, or interference, severe inter-symbol interference (ISI) occurs, significantly degrading decoding performance. Existing methods mitigate ISI by reducing LED transmission signaling density.This paper proposes a robust decoding framework that maintains full LED signaling density. We introduce a pilot-aided geo-metric recognition with a PSF-constrained Hough transform and circle center alignment refinement. By leveraging prior structural knowledge from pilot frames, the system effectively separates overlapping LED signals under severe optical distortion.Experimental results on a real-world VLC testbed confirm that the proposed method achieves superior decoding accuracy and throughput compared to conventional Hough-based and low-density baseline methods. The results highlight its potential for high-efficiency VLC applications in interference-prone environments. © 2025 IEICE.