User Manual - pancroma

During the internal processing of the band files, color information is extracted andplaced in intermediate scratch files that match the panchromatic file in size.Since Landsat band files are only ¼ the size of the panchromatic file, thesesparse files are interpolated to fill in the empty spaces in the data arrays.Increasing the number of interpolation iterations does not usually improve thequality of the results appreciably. Accept the default for the first run.After selecting the number of iterations, the program will begin computing yourpan-sharpened image.IMPORTANT NOTE: If you are submitting a full Landsat data set, computationtime can vary: around 200 seconds on a powerful computer under the bestconditions and as much as three hours on a slow computer. This is because thesheer volume of input and process data will exceed the application addressspace segment allowed by the Windows operating system. This is true no matterhow much RAM your system has installed. When the input file size exceeds apractical cutoff, the program will make scratch files on your hard disk for storingtemporary data, and disk access is slow compared to RAM access. When theprocess is complete, PANCROMA TM will display the panchromatic image.IMPORTANT NOTE: Without special automatic image processing techniques,some spectral distortion may occur during the four file HSI pan sharpeningprocess when processing Landsat data. This may cause green colors of the pansharpened image to look unnatural. Sometimes the default settings will producevery acceptable results. This is especially true of Landsat data sets due to thespectral characteristics of the panchromatic band. PANCROMA TM can employseveral automatic techniques to deal with this problem. These will be discussedin the following sections. PANCROMA TM also offers an extensive set of manualimage preprocessing and post processing utilities.49