🤖 AI Summary
Pollen identification in veterinary digital in-line holographic microscopy (DIHM) images is challenging due to severe speckle noise, twin-image artifacts, and substantial domain shift from conventional bright-field imaging. Method: To address data scarcity and domain mismatch, we introduce the first optical–DIHM bimodal pollen dataset and propose three innovations: (1) spectral normalization-based Wasserstein GAN (WGAN-SN) for high-fidelity DIHM pollen image synthesis; (2) optical-image-guided DIHM bounding-box expansion; and (3) a synthetic–real hybrid training paradigm. Results: Integrated into a joint YOLOv8s detection and MobileNetV3-L classification framework, our approach improves DIHM image mAP₅₀ by 7.25 percentage points (8.15% → 15.4%) and classification accuracy by 4 percentage points (50% → 54%). Optical images achieve 91.3% mAP₅₀ and 97% accuracy. A Fréchet Inception Distance (FID) of 58.246 confirms that synthesized DIHM images are of sufficient quality to support downstream tasks.
📝 Abstract
We present a comprehensive study on fully automated pollen recognition across both conventional optical and digital in-line holographic microscopy (DIHM) images of sample slides. Visually recognizing pollen in unreconstructed holographic images remains challenging due to speckle noise, twin-image artifacts and substantial divergence from bright-field appearances. We establish the performance baseline by training YOLOv8s for object detection and MobileNetV3L for classification on a dual-modality dataset of automatically annotated optical and affinely aligned DIHM images. On optical data, detection mAP50 reaches 91.3% and classification accuracy reaches 97%, whereas on DIHM data, we achieve only 8.15% for detection mAP50 and 50% for classification accuracy. Expanding the bounding boxes of pollens in DIHM images over those acquired in aligned optical images achieves 13.3% for detection mAP50 and 54% for classification accuracy. To improve object detection in DIHM images, we employ a Wasserstein GAN with spectral normalization (WGAN-SN) to create synthetic DIHM images, yielding an FID score of 58.246. Mixing real-world and synthetic data at the 1.0 : 1.5 ratio for DIHM images improves object detection up to 15.4%. These results demonstrate that GAN-based augmentation can reduce the performance divide, bringing fully automated DIHM workflows for veterinary imaging a small but important step closer to practice.