The display of pixel values in a 2D scatter plot for a high resolution image in floating point values can be resource intensive. So ENVI will use a subset of these points. ENVI Classic 2D scatterplots take the pixels from the Display window only. If you maximize the display window, the scatterplot will show more pixels. If you increase the resolution of your desktop and maximize the Display window, the scatterplot will show even more pixels but if the image is very large, it may get very slow. ENVI 5 allows the use of all pixels for 'small to medium size' images but for very large images, the memory requirements can be too large to display and still provide good display performance.

While this makes perfect sense as a default behavior, could this be modified to allow the user to view the entire scene? If she/he has the time or computing power, then let them make this choice. If the developers think it would be best, they could add a pop-up window with a warning, kind of like what our mothers may have done when they thought we were making a decision they disagreed with. But let us do what we think is needed. Oh, and add a Cancel button so we can bail out when we discover we are wrong in our choice? ;-)