The study investigates effect of shape on gas bypassing and mixing of gas-fluidized Geldart A particles. A shallow Fluidized Bed (FB), configured at bench-scale, was used with Digital Image Analysis (DIA) for the investigation. The extent of scatter of tracer particles throughout the bed was assessed from DIA images of defluidized powder. A novel method, employed Jupyter notebook software, which directly determined Mixing Index from the images. Remarkably, Platelet-shaped China clay powder displayed the best mixing characteristics (Mixing Index: 0.79) with no significant bypassing. Angular shaped Quartz displayed moderate mixing (Mixing Index: 0.67), but high bypassing (Bypassing Index: 0.75). Contrary to conventional assumptions, spherical diatomite exhibited poor mixing (Mixing Index: 0.61) with the highest bypassing (Bypassing Index: 0.82). Platelet particles performed well even with fines removal or larger particles addition. Most likely, particle shape significantly influenced the number of available particle contact points, tracer migration, and tracer on particle binding.