We use PixInsight and Photoshop to process our images. Both software packages have their strengths in astro image processing.
PixInsight handles all of our preprocessing (image calibration, registration and integration), linear processing (removing background gradients, deconvolution, denoising and linear fitting), stretching, channel combination, global color calibration, global curves adjustment, and nonlinear sharpening. PixInsight’s masking capabilities are great, and make it very easy to mask stars or structured objects in the image. While we are able to achieve very nice results within PixInsight, we are not experienced enough to use PixInsight’s masking and other processes to bring out targeted details and colors in specific locations throughout the image. While this might be possible, we find using Photoshop easier for our final processing.
While we sometimes use Photoshop’s global tools, we mostly use Nik plugins Viveza (for color correction) and ColorEfex Pro (for detail extraction and tonal contrast). Nik offers control-point masking and live-view sliders within its tools, making it very easy to apply a correction to one or more narrowly targeted spots. Using these tools to bring out faint details, enhance contrast and pop the color turns our nice images from PixInsight into our final works of art. We have found that Nik tools are most effective when used incrementally. Rather than apply multiple corrections to a single control point, one correction is applied, saved to a new layer, then the next correction is applied.
The modules within Nik ColorEfex Pro which we routinely use are:
This comparison shows our image of IC 1805, the Heart Nebula, after finishing our PixInsight processing (left) and after finishing our additional Photoshop processing (right).
This is a 100% crop of the Heart Nebula image which clearly shows the results of targeted detail/contrast and color correction using the Nik plugins in Photoshop. Again, the image after PixInsight processing is on the left, and after Photoshop processing is on the right.
Step by step Photoshop processing of this image. You can view a larger version of this image on Flickr.