By default TreeView images are only 8 bits per pixel which distorts photo-realistic images. On the desktop you can change this with the Door library as shown. Unfortunately on the device this is not possible so the code will not work there. Obj1 is a Door library object.
B4X:
tree.ImageSize(64,64)
tree.ImageMode = True
' must be after setting ImageMode
Obj1.New1(False)
Obj1.Value = tree.ControlRef
Obj1.Value = Obj1.GetProperty("ImageList")
Obj1.SetProperty("ColorDepth", 24)