SKY_September2014.pdf

68 September 2014 sky & telescope

Image Processing

Gradients

CONQUERING

Get the most out of this powerful technique in PixInsight.

Rogelio Bernal Andreo

Gradients. It’s the one thing every deep-sky astrophotographer has to deal with

sooner or later. They appear in images as an uneven background, often introducing

unwanted color biases and overpowering the signal of your subject galaxy, nebula, or

star cluster. In an ideal world, astrophotographers wouldn’t have to address gradients,

and we wouldn’t have to worry about things such as noise, either. But unlike noise, we

can remove gradients from our images without compromising the underlying data.

ALL PHOTOS ARE COURTESY OF THE AUTHOR

PixInsight.indd 68 6/23/14 12:17 PM