Patent ID: 7480052
Filing Date: 2009-01-20
Classification: G06K

Abstract:
1. A method of detecting clouds in a digital image, the method comprising the steps of: for an area of the digital image, determining a reflectance value R1 in a discrete electromagnetic spectrum band from 400 nm to 460 nm, a reflectance value R2 in a discrete electromagnetic spectrum band from 630 nm to 690 nm and a reflectance value R3 in a discrete electromagnetic spectrum band from 830 nm to 890 nm; computing in a first computing step a first ratio of the R3 reflectance value minus the R1 reflectance value and the same two values added together; computing in a second computing step a second ratio of the R3 reflectance value and to the R2 reflectance value; choosing the R2 reflectance value; and concluding that an opaque cloud exists in the area if the results of each of the two computing steps and the choosing step fall within three corresponding predetermined ranges.