Fast full-color pathological imaging via an optimized illumination pattern with color transfer in Fourier ptychographic microscopy (OIP-CTFPM).

Whole slide imaging (WSI) has become the core of digital pathology, yet its inherent drawbacks, such as stitching artifacts and high costs, have motivated the pursuit of stitching-free and cost-effective imaging solutions. Fourier ptychographic microscopy (FPM) represents a promising stitching-free technology for next-generation digital pathology. Traditional full-color high-resolution (HR) imaging needs to synthesize the independent reconstruction of HR images from three channels (red, green, and blue), which leads to excessively long overall processing time. To reduce imaging time, this study proposes sparse illumination patterns combined with color transfer to accelerate full-color HR images without significantly compromising image quality. According to theoretical simulations of wavelet-transform FPM, two kinds of sparse illumination patterns (45-LED pattern and 57-LED pattern 1) demonstrate better performances than the other five kinds of illumination patterns in the metrics of PSNR and SSIM. In the resolution validation of the phase plate, the 57-LED pattern 1 outperforms the other patterns, which have the same resolution (435 nm) as the full sampling pattern under a 4X objective with NA 0.1. Based on the 57-LED pattern 1 combined with color transfer, the overall scheme saves four-fifths of the imaging time while maintaining a resolution comparable to the ground truth (full sampling). This method can be applied in the WSI of the pathological slide of lung cancer for cancer diagnosis. The joint approach of sparse illumination and color transfer effectively reduces imaging time and yields favorable performance of whole slide pathological imaging.