Image processing method was applied to analyze the dying process at different locations on test cylinders in order to examine the variation of the surface chroma during the test.A complete test was divided into three stages:sub-dyed

balanced and over-dyed.The chroma distribution of balanced stage was normalized and defined as local water collection efficiency.Droplet impingement limits and the ratio of total impingement to the maximum local impingement efficiency can therefore be analyzed by the colorimetric integration curves.Comparing to the numerical simulation and the experiment of NASA (National Aeronautics and Space Administration)

the current results indicate that water droplets impingement characteristics can be correlated with the dynamic RGB(rad-green-blue) color space

with ±15% repeatability error.Interrelation among the three characteristics was also observed.