ENVI ® (the Environment for visualizing Images) is a revolution of digital image processing system. From the beginning of the birth, ENVI has been designed for many specific requirements on who typically use satellite remote sensing data or aerial photographs. ENVI provides data visualization and comprehensive analysis for the image in any size and any type of environment in which innovative and user-friendly.
Atmospheric correction performed on the radiometric image is distorted. Or to say also that the radiometric correction performed due to interference from atmospheric effects as the main source of error. Distortion can occur during data acquisition and transmission or recording of the detectors used in the sensor with the characteristics of errors include: - The existence of the missing pixels - Effects of the atmosphere that causes the shadow scattering object - The appearance of lines caused by the lack of uniformity detectors Correction of the above can use the histogram adjustment method (histogram adjustment). The assumption underlying this method is the lowest pixel value of each channel should be 0. If the value is greater than zero (> 0), then calculated as the bias or offset, and the correction is done by removing the bias, which reduces the overall value of the original spectral channels with a value bias respectively. In ENVI Band Math can be performed with or Dark Substract Basic Tools> Band Math then enter the formula Reduction of the bias, for example: B1-54 done for each band, with each value of bias Basic Tools> Preprocessing> General Purpose Utilities> Dark Substract select the image, then all bands will be corrected (if any bands / channels are in one file) To check the value of vulnerable band / channel Select Basic Tools> Statistics> Statistics Compute