Individual getters and setters on GPUImageLevelsFilter

I'm actually developing an application on desktop (using GPUImage Mac) that generates filter class. The user has an interface an add the filter one by one and chain them. The user can set every fields in every GPUImage filters and actually see what's going on on an image he loaded previously. I was thus in need of the individual getters and setters in GPUImageLevelsFilter, so when the setting view shows up it can set its various cursors at the right position using getters, and set the individual fields when the user moves cursors using the setters.