Plant leaf color is an important indicator for diagnosing the plant nutrient status. A software was developed by Crop Environment and Production Technology Lab. of Seoul National University to analyze the color image of rice canopy taken at panicle initiation stage (PIS) with digital camera and to recommend nitrogen fertilizer rate for target yield or protein content of rice. The software was coded in Visual Basic Ver. 6.0 and includes subroutine to calculate color indices from the digital image and several model equations relating the color indices to biomass and nitrogen accumulation of rice canopy at PIS, the grain yield to nitrogen density at PIS (PNup) and nitrogen accumulation from PIS to maturity (PHNup), and the PHNup to PNup and nitrogen fertilization rate at PIS. The objective of this study were to test the performance of the Software. Using the Software, nitrogen fertilization rate at PIS was recommended targeting the rice protein content of 6.3% for the 12 plots subjected to different amount of basal and tillering N fertilizer. N recommendation using the software reduced the coefficient of variation (CV, %) of rice yield and protein content among plots compared to the conventional N treatment plots. However, the actual protein content of rice was lower than the predicted value. This discrepancy would be attributable to the much better weather condition during grain filling period in 2009 compared to the normal year that assume in the Software for N recommendation. Additional calibration process is needed to improve the accuracy of this Software.