In Nebulb all the adjustments that are applied are non-destructive, that is, you can make all the changes you want without degrading the image quality.
This is because Nebulb always keeps the images internally in the color space of the camera and at 32 bits. In this way, the resulting stacked images contain much more information than the original RAW, thanks to which Nebulb is then able, among other things, to achieve a great light pollution reduction.
This also makes it possible to undo and redo adjustments without any loss of image quality.
Undo changes
To undo the last adjustment you have applied, simply press the key combination "Ctrl + Z" or click on the menu "Edit -> Undo".
This action will undo the last of the adjustments you have made. And in case you want to undo more adjustments, you can apply it several times and the adjustments will be undone in order.
Redo changes
Analogously to the above you have the option to redo changes you have undone by pressing the key combination "Ctrl + Y" or by clicking on the menu "Edit -> Redo".
Just keep in mind that this action can be applied right after you have undone any adjustments, as long as you have not yet applied any new changes.
Restore default settings
Nebulb allows you to reset the default settings of each of the tools at any time (in case you are not satisfied with the settings you have applied and want to start over quickly).
To do this you must press the "Alt" key and when you do so you will see a broom-shaped button appear next to the header of each of the tools.
And if you press the broom button, Nebulb will automatically reset the tool's settings to their default values:
ATTENTION: The undo changes option does not apply to this action, i.e., if you reset the default settings of a tool and then want to return to the values you had previously, you will have to do it by adjusting each of the controls again by hand.