The bulge test a highly adaptable mechanical testing method extensively employed in biomedical fields materials science and engineering to comprehend material and structural mechanical behaviors. In this investigation, a biocomposite blown film made of PLA and 2wt.% of date palm leaf powder (PLA_2%) underwent characterization via the bulge test, with subsequent property comparisons to uniaxial testing results. Employing 3D digital image correlation (3D-DIC) ensured more precise and accurate deformation measurements, offering superior capabilities in testing while detecting defects like cracks, voids, and delamination. Throughout the bulge testing, 3D-DIC enabled the analysis of strain field evolution within the sample and confirmed the isotropic deformation of the film sample in the elastic deformation region, as evidenced by the perfect isodisplacement lines of the bulged film bubble, and the same maximum and mean deformation along the transverse direction (TD) and the machine direction (MD) of the film sample. As the deformation progressed, the deformation became anisotropic, with the bubble shape gradually shifting towards an elliptical form, indicating deviation from the ideal spherical shape due to plasticity. Uniaxial characterization showed a significant difference in the deformation at break for the film along the TD and the MD. 3D-DIC analysis revealed that while the sample undergoes comparable average deformation in both the TD and MD under the same loading conditions, it shows a higher strain concentration specifically, double the amount in the TD compared to the MD. The strain concentrations in the TD are manifested within bands that run parallel to the blown direction, indicative of localized thickness reduction in those regions.