Abstract: A computer-implemented method, apparatus, and system for interactive identification of subsurface regions that represent lithology and/or fluid anomalies that indicate the presence of hydrocarbons may be provided. Since the introduction of AvO classes, AvO interpretation has largely been quantitatively driven through polygonal selection of non-background trend values from cross plots of seismic and/or derived seismic attributes such as intercept and slope. Embodiments of the invention may provide a system and/or method which allows qualitative and quantitative, interactive, visual observation of AvO and petrophysical classes and projections simultaneously, through, for example, co-blending based an intuitive parameterization of gradational color tables with varying opaqueness along axes representing respectively background trend and anomaly, or petrophysical variables.