A thin and lensless two-dimensional (2D) to three-dimensional (3D) convertible display based on integral imaging using an organic light emitting diode (OLED) panel as a direct emissive light source is proposed with improved optical efficiency. A point light source array for 2D-3D convertible display is formed on the surface light source, i.e., the OLED panel. However, a blurring effect and color separation result from the finite (nonzero) size of point light sources since each point light source is generated by a pixel of the OLED panel. Simulation results for a blurring effect and color separation in terms of rays from a light source with finite size is presented. The proposed system has a thin structure and simple convertibility because it does not need any additional optical element to provide 2D-3D convertibility.