GraXpert is designed to remove gradients from astroimages. As the name suggests, gradients are gradual changes in brightness that are not part of the astrophoto but are caused by external interference. Causes can be e.g. light pollution or incorrect or missing flat correction, but also natural brightness gradients of the night sky and peculiarities of the optics used (shading in the form of a vignette).

In order to edit deep-sky photos, it makes sense to remove such gradients from the images. Not only does it look better, but also simplifies further processing of the image. Color casts can also be removed in this way and it generally makes sense to free the astrophoto from the amount of the sky background. In short: A gradient removal is very useful, if not mandatory.

GaXpert is freely available open source software that was programmed exclusively for this purpose. It works stand alone, not as a plug-in for any other software.