<p>Rock mass classification systems are fundamental to the design of rock structures and are widely applied in rock engineering. Among these systems, the geological strength index (GSI) is particularly significant as a commonly used classification method. GSI comprises four primary parameters: the uniaxial compressive strength of intact rock (σ_ci), discontinuity spacing (S_d), rock quality designation (RQD), and the condition of discontinuities (C_d). Notably, RQD is inherently linked to discontinuity spacing, with both parameters collectively accounting for approximately 42% of the GSI ratings. Evaluating S_d and RQD through conventional methods is challenging due to the variation in measured S_d and RQD across different scanline orientations and the lack of a standardized criterion for their determination. Rock masses consist of heterogeneous elements of various sizes and shapes, interlocking like a three-dimensional puzzle, which complicates the assessment of block size distribution. Image analysis techniques offer an effective solution to capture the roles of both S_d and RQD within the GSI framework. In this study, the parameters σ_ci, RQD, S_d, C_d, and the median block size (F₅₀) were measured across 96 scan lines in various mines, trenches, and tunnels. Analysis of the results revealed a good correlation between GSI and the combination of the discontinuity condition rating (R_cd) and F₅₀. Consequently, a new relation was developed, linking GSI to these parameters, thereby simplifying the GSI assessment process.</p>