FIA (菲亚): Fluorescence Image Aligner

Robust Motion Correction for Biological Time-Lapse Microscopy
Specialized for Calcium Imaging (G/R-CaMP), Voltage Imaging, and Long-term Live Cell Monitoring.

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(FIA corrects both global drift and local tissue deformation)

📖 Overview

FIA (Fluorescence Image Aligner, 菲亚) v3.1.0 is a major update designed to solve the full spectrum of motion artifacts in fluorescence microscopy.

Whether you are dealing with sub-pixel jitter in functional imaging or complex tissue deformation in behaving animals, FIA provides a unified solution. It bridges the gap between high-precision rigid alignment and robust non-rigid registration.

🚀 What's New in v3.1.0?

• New "Dense Flow" Engine: A robust non-rigid registration mode using Temporal Averaging (Super Reference) and CLAHE pre-processing.
• Smart UI: Parameter panels now dynamically adapt to your selected mode.
• Scientific Validity: Strict separation of alignment calculation (using enhanced images) and pixel transformation (using raw data).

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✨ Key Features

1. Dual-Engine Core

• OpenCV ECC: Best for high-precision, sub-pixel rigid alignment (Rotation/Translation).
• Dense Flow (New Standard): State-of-the-art local deformation correction. Handles internal tissue warping better than any rigid method.
• Legacy Mode: A fallback engine based on Kang Li's "Image Stabilizer" for systems without OpenCV support.

2. Scientific Integrity

• Intensity Preservation: FIA guarantees that your ΔF/F analysis remains valid.
  • Navigation: Motion vectors are calculated using noise-reduced, contrast-enhanced temporary frames.
  • Transport: These vectors are applied to your original raw data using cubic interpolation.
  • Result: No artificial contrast or brightness is written to your final image.

3. Smart "Super Reference"

• In Dense Flow mode, FIA creates a reference anchor by averaging N frames (user-definable). This eliminates the "floating anchor" problem caused by shot noise in single-frame references.

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📥 Installation

1. Download the latest FIA-3.1.0.jar from the Releases Page.
2. Drag and drop the file into your Fiji/ImageJ plugins folder (or main window).
3. Restart Fiji.
4. Navigate to: Plugins > Biosensor Tool > FIA Image Aligner.

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🎮 Usage Guide

1. Engine Selection

Mode	Description	Best For
Global (Step 1)	Translation / Rigid / Affine	Corrects general XY drift and Rotation. (Recommended for behaving animals).
Dense Flow (Step 2)	(Recommended) Uses Super Reference + CLAHE.	95% of Biological Samples. Noisy fluorescence, brain slices, in vivo imaging.
Elastic (Step 2)	(Legacy) Raw optical flow without preprocessing.	High-SNR Data. Binary masks, artificial beads, or clean data where contrast enhancement is harmful.

2. Controller Settings

(The new Smart UI in v3.1.0 adapts to your selected mode)

• Global Settings (Hidden in Local Mode):

  • Max Iterations: Loop limit for Rigid/Affine calculation.
  • Precision: Convergence threshold ($10^{-x}$).

• Dense Flow Settings (New):

  • Flow WinSize: The "field of view" for local alignment.
    • Small (5): Captures fine jitter.
    • Large (15+): Captures global tissue waves.
  • Ref Depth: Number of frames averaged to create the "Super Reference". (Default: 5).
  • Poly N: Smoothing factor. 5 (Sharp) vs 7 (Blur/Noisy).

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📚 Algorithm References

FIA is built upon the following established computer vision algorithms:

1. Non-Rigid Registration (Dense Flow)

• Farnebäck, G. (2003). Two-Frame Motion Estimation Based on Polynomial Expansion. SCIA 2003.
• Zuiderveld, K. (1994). Contrast Limited Adaptive Histogram Equalization (CLAHE). Graphics Gems IV.

2. Rigid / Affine Alignment (ECC)

• Evangelidis, G. D., & Psarakis, E. Z. (2008). Parametric Image Alignment using Enhanced Correlation Coefficient Maximization. IEEE TPAMI.

3. Legacy Stabilization

• Li, K. (2008). The Image Stabilizer Plugin for ImageJ.
• Lucas, B. D., & Kanade, T. (1981). An Iterative Image Registration Technique with an Application to Stereo Vision. IJCAI.

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📚 Citation

If you use FIA in your research, please cite:

@software{wang_fia_2026,
  author = {Wang, Kui},
  title = {FIA: Fluorescence Image Aligner - Robust Motion Correction for ImageJ/Fiji},
  version = {v3.1.0},
  year = {2026},
  url = {[https://github.com/Epivitae/FIA-Fluorescence-Image-Aligner](https://github.com/Epivitae/FIA-Fluorescence-Image-Aligner)},
  doi = {10.5281/zenodo.18206931}
}

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© 2026 Dr. Kui Wang | Chimeric Nano Sensor Team | www.cns.ac.cn