The effect of time on nanopore structures formed via electrochemical anodization of high purity Al2O3 was investigated. The electrochemical bath consists of 5 % phosphoric acid electrolyte; a platinum electrode was used as the cathode electrode, and TLC (thin layer chromatography) aluminium film as anode electrode. It is found that the regularity of nanopores arrangement can be significantly improved by increasing anodizing time at constant temperature and voltage. It is observed after the anodizing process, that at every interval of time there is a significant decrease in wall thickness from 58-26nm and increase in the nanopore diameter size about 31-86 nm. According to Nielsch, self-ordering of porous alumina requires a porosity of 10 % independently of anodizing conditions. It means that the most optimum anodizing conditions always results in a porosity of 10 %. The result optimized at 30 min is well matched with 10 % porosity. The morphology and phase composition were characterized by field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDX). The nanopores thin film images obtained by FESEM are used for image analysis using MATLAB software and porosity and nanowall thickness results are compared with experimental and automated methods, which demonstrate the efficacy of the proposed method.