Fig. 1. Feature analysis of phase contrast microscopy image. (a) Cell image; (b) gray value distribution at longitudinal lines; (c) gray value distribution at transverse line

Fig. 2. Flow chart of the proposed method

Fig. 3. Dual-Gaussian filtering process. (a) Input image; (b) Gaussian filtering (large kernel); (c) Gaussian filtering (small kernel); (d) difference calculation

Fig. 4. Effect of different σ₂ values ​​on the segmentation results

Fig. 5. Relationship between σ₂ value and standard deviation of f_dg

Fig. 6. Comparison diagrams before and after dual-Gaussian filtering. (a) Before processing; (b) grayscale mapping before processing; (c) after processing; (d) grayscale mapping after processing

Fig. 7. Binary segmentation image. (a) Threshold segmentation; (b) hole filling; (c) area constraint

Fig. 8. Segmentation results of low-density cell images processed by different algorithms. (a) Cell image; (b) 2D-Otsu algorithm; (c) Jaccard algorithm; (d) Flight algorithm; (e) Vicar algorithm; (f) proposed algorithm

Fig. 9. Segmentation results of medium-density cell images processed by different algorithms. (a) Cell image; (b) 2D-Otsu algorithm; (c) Jaccard algorithm; (d) Flight algorithm; (e) Vicar algorithm; (f) proposed algorithm

Fig. 10. Segmentation results of high-density cell images processed by different algorithms. (a) Cell image; (b) 2D-Otsu algorithm; (c) Jaccard algorithm; (d) Flight algorithm; (e) Vicar algorithm; (f) proposed algorithm

Fig. 11. Comparison of segmentation results of different algorithms in complex situations