Please add an Offset feature (often placed next to Gain) to ASIAIR: -- Most Astro camera applications allow for an Offset in addition to Gain settings for each camera.
According to Dale Ghent "Offset is exactly as its name implies: it is an offset that is applied to the histogram curve which shifts it – offsets it – farther to the right on the histogram by some amount. This ensures that the minimum value that any pixel might record is not underexposed and is therefore clipped in the blacks. This is especially important in astrophotography because of the nature of it – some pixels on the sensor might be positioned to look at purely dark space and therefore will collect far, far fewer photons than pixels that has the light from a star, nebula, or other light-producing object pouring into it.
Avoiding clipped-black pixels means that you avoid having pixels with insufficient signal or, worse, a value of 0. This is the opposite predicament of an image that has pixels that are clipped-white. Both types of clipped pixels effectively have no data that can be meaningfully acted upon during processing."
