<p>With the advent of polarization imaging sensors, flow-induced birefringence has emerged as a promising method for measuring fluid shear stress distributions. A primary challenge in establishing this measurement method is the determination of the photoelastic coefficient, which links measured retardation to the shear stress. In this study, we demonstrated quantitative imaging of a two-dimensional shear stress distribution based on flow-induced birefringence using polarized-image sensing. Cellulose nanocrystal (CNC) suspension was employed as the working fluid, and its photoelastic coefficient was calibrated in a circular Couette flow where the theoretical shear stress distribution can be analytically calculated. Based on the stress-optic law, shear stress was reconstructed from polarization intensity measurements using a camera equipped with a polarization image sensor. Using the calibrated photoelastic coefficient, we conducted quantitative measurements of the cumulative shear stress distribution of the fluid flowing vertically through a rectangular channel. The experimental results showed a distribution consistent with expectations, exhibiting low shear stress at the channel center and high stress near the walls. Furthermore, a numerical simulation was performed to verify the experimental findings. The simulation results showed good agreement with the experimental data in terms of the minimum values and the overall trend of the cumulative shear stress. In summary, the present study successfully demonstrates the fundamental feasibility and potential of polarized-image sensing for the quantitative evaluation of local shear stress fields.</p> Graphical abstract <p></p>