Image analysis provides an accurate and precise method of pest evaluation. The objective of this work was to compare the usefulness of the ImageJ® 1.43u image processor and visual estimation as methods to characterize brown rust lesions and estimate the resistance of new sugarcane cultivars. For this, leaves images of 10 cultivars were captured and the parameters quantity, most frequent size of the pustules and leaf area affected were determined. The data were correlated with the evaluations of the eight control (standard) genotypes to obtain a classification of disease resistance. The results showed that the software’s determinations were the most accurate, although all the methods were reliable for rating the reaction to brown rust.