Hi, I use ENVI 5.6.3 for my drone imagery analysis. The background around of my region of interest is set to No Data via edit metadata with the data ignore value set to 0, and thus appears as white (or mabye this is transparent). I am applying thresholds via the decision tree classifer to classify my drone imagery into bare, herbaceous and woody classes. But, the background area also gets classified as bare, which affects the statistics and the confusion matrix calculations. I tried to subset the classified map but this does help. I also tried to make the cover classes as bare = 1; herbaceous = 2 and woody = 3, instead of the default output which labels the classes from 0. Is there a way to fix this?

Thank you.