Hi, I want to classify SPOT 7 multispectral image in ENVI 5.1. After I created subset image of my study area using ROI, background data (the pixel values outside of the ROI data) occurred. Background data has zero pixel value. In order to mask background pixels, I created ROI from band thresholds and chose thresholds parameters for all bands as min value=0; max values=0 and then saved ROI to .xml. I selected the subset image as classification input file. I imported "mask ROIs xml" using mask options. . I selected “Selected Areas "Off” option from the mask definition menu bar. After I created the mask file, I selected mask band in classification input file menu. Mask band has pixel values=1 for subset part and pixel values =0 for mask part. After classification process, background or masked pixels was assigned as unclassified class. I want to leave those pixels out of my classification, because unclassified class affected class statistics results and classification accuracy results. How can I do this? Thanks.