FlowRoI A Fast Optical Flow Driven Region of Interest Extraction Framework for High-Throughput Image Compression in Immune Cell Migration Analysis

TL;DR

FlowRoI is presented, a fast optical-flow-based region of interest (RoI) extraction framework designed for high-throughput image compression in immune cell migration studies and yields higher peak signal-to-noise ratio (PSNR) in cellular regions.

Abstract

Autonomous migration is essential for the function of immune cells such as neutrophils and plays a pivotal role in diverse diseases. Recently, we introduced ComplexEye, a multi-lens array microscope comprising 16 independent aberration-corrected glass lenses arranged at the pitch of a 96-well plate, capable of capturing high-resolution movies of migrating cells. This architecture enables high-throughput live-cell video microscopy for migration analysis, supporting routine quantification of autonomous motility with strong potential for clinical translation. However, ComplexEye and similar high-throughput imaging platforms generate data at an exponential rate, imposing substantial burdens on storage and transmission. To address this challenge, we present FlowRoI, a fast optical-flow-based region of interest (RoI) extraction framework designed for high-throughput image compression in immune cell migration studies. FlowRoI estimates optical flow between consecutive frames and derives RoI masks that reliably cover nearly all migrating cells. The raw image and its corresponding RoI mask are then jointly encoded using JPEG2000 to enable RoI-aware compression. FlowRoI operates with high computational efficiency, achieving runtimes comparable to standard JPEG2000 and reaching an average throughput of about 30 frames per second on a modern laptop equipped with an Intel i7-1255U CPU. In terms of image quality, FlowRoI yields higher peak signal-to-noise ratio (PSNR) in cellular regions and achieves 2.0-2.2x higher compression rates at matched PSNR compared to standard JPEG2000.

Figures (9)

• Figure 1: Framework of FlowRoI for high-throughput image compression in immune cell migration analysis.
• Figure 2: Comparison of FlowRoI and JPEG2000 in image quality using PSNR and instance segmentation using precision, recall and F1 score.
• Figure 3: Qualitative comparison of FlowRoI and JPEG2000 with different compression rate.
• Figure 4: Qualitative intermediate outputs with different settings of denoise, RoI threshold, and adjacent factors. After applying denoising, several scattered and irregular artifacts (highlighted in yellow) are effectively removed, resulting in cleaner RoI masks without affecting the main cell regions.
• Figure 5: Examples of cell missing cases (TP: true positive, FP: false positive, FN: false negative, and TN: true negative).