create preview coded
preview generated, but probbaly channels not read properly. need to guess how they are stored in memory
preview generated properly
minor changes
navigation with preview loading after zooming still not working, lines at preview appear green. why?
green lines problem solved by using unsigned chars
preview only generated if it didn't exist yet
now during whole navigation process, only preview is loaded. this avoids problems when appending char images and float images
For very large data, previsualization generation is too much time and memory consuming --> decimate preview accessing, for example, only one out of 4 pixels, and interpolating the rest.   Navigation with mouse on zoomed image now fails.   Sometimes mouse releases are not noticed.
attempt to generate downsampled preview, but not working
eventual crashes
minor changes
indentation changes for eclipse integration
navigation finally works well, problem was the area to be cropped after appending a new image part
first intent to add preview to the navigation, now that navigation works fine
problem about right side of the image solved, navigation almost perfect
problem when switching to scaled size mode (W key) solved, by assigning the image to the main_display instead of displaying it
minor changes. navigation works almost perfect in all cases. random bugs when pressing W key that cause X Error of failed request. TODO: solve the fact that when navigating, the preview doesn't follow the curstor position at all, even though when the right button is released, the HD image IS in the right position