About color correction in astrophotography

Color correction in standard images is mainly based on con- trolling the interaction of illuminant and reflectance and often re- sults in a compensation of actual chromatic casts with respect to a chosen reference illuminant. Primary reference illuminants come from our reference star, the sun, whose color characteristics are of G2V star class. Visually, color correction in standard im- ages allows us to obtain scene colors more pleasant and closer to our everyday experience. Quality of color is usually intended to please the vision system of the observer, that looks at the picture using the powerful mechanisms of visual color and contrast ad- justment (color constancy), a very different tool with respect to a camera. In astrophotography this basic principle does not apply: the illuminants of the many different stars or emission nebulae are the only information we detect, while the only reflectance involved (not considering Solar System planets) is originated by dust par- ticles producing the so called reflection nebulae. Thus, what is the meaning and the goal of color correction in astrophotogra- phy? In this paper, we try to present to the reader some points of discussion about this broad question.