Poor imaging is frequently observed in many subsalt regions, making the subsalt stratigraphy interpretation and prospect evaluation challenging. We propose a critical reflection illumination analysis to evaluate subsalt illumination in areas where high-velocity contrasts create illumination and imaging shadows. Critical reflection often occurs at the base or flank of salt bodies. If critical reflection occurred, continued iterations of processing and imaging would generate little, if any, improvement in imaging results. Similarly, increasing the offset/azimuth of the acquisition would offer limited or no advantage. We introduce the critical reflection illumination map and illumination rose diagram to efficiently and effectively evaluate the probability of critical reflection for the target. This analysis can help avoid expensive processing, imaging, and acquisition efforts for areas that are in the critical/postcritical reflection regime. Critical reflection illumination analysis can also be applied to other high-velocity contrast scenarios.