Line intensity, ratio, and optical images of NGC 3627. Top panels: NGC 3627 [C I](1−0) (left) and CO(2−1) (right) integrated line intensity (moment-0) maps within our broad mask (representing high-completeness signals; see Appendix A). Bottom left panel: [C I](1−0)/CO(2−1) line ratio map within the combined signal mask. Bottom right panel: HST F814W − F555W − F438W RGB composite image (PHANGS-HST; Lee et al. 2022). Regions marked with the white boxes and labeled with numbers are mainly for illustration purpose and for discussion in the text. Their zoom-in images and extracted spectra are provided in our online data release. Examples for regions 1, 4, and 22 are presented in Appendix D. All images have the same field of view of 179″ × 179″ or 9.83 kpc × 9.83 kpc.