Digital image analysis (DIA) was used to achieve some information related to aspect ratio of the bubbles, bed expansion fluctuations and the emulsion area at different gas velocities and different bed heights. All experiments were done in a pseudo-2D gas-solid fluidized bed. Variations of the bubble fraction at different gas velocities and different bed heights were investigated. It was found that when the excess gas velocity increases, the dimensionless bed height increases linearly with slope of about 0.4 for LLDPE particles. To validate the analysis, the bubble diameter achieved by DIA results in this work was compared with the bubble diameter correlation presented by Shen et al. Bubble aspect ratio in different heights of the bed was extracted through image analysis, and it was observed that the bubble aspect ratio first increases with the bed height and near the freeboard becomes flattened. Results of the experiments show that the emulsion phase becomes more expanded at higher excess gas velocities. As demonstrated by the analysis results, by increasing the bed height, bubble fraction parameter is decreased.