Once our luminance image is enhanced with HDR Transformation, Sharpening and Dark Structure Enhancements, we need to integrate this back into the original color image. The overall goal with luminance integration should be to
- Brighten the image without brightening to background.
- Increase the clarity of high signal areas
The LRGB Combination process is used to integrate the luminance channel with an RGB image. If your luminance image contained stars, you can simply use the LRGB Combination and apply it to the color image.
This process simply requires the selection of the luminance image and then to determine the weights for lightness and saturation
- Lightness: Increasing the number reduces the luminance brightness
- Saturation: Decreasing the number increases the color
It is best to run through this a with a few different settings to identify the best result
However, if the luminance image was a starless image, you will need to apply a star mask (inverse) to the color image to protect the stars.
The right option is up to personal preference. But I prefer 50:40 for the first image and 50:50 for the second.
Overall, spending the time to create an enhanced luminance definitely improves the overall quality of the image.
The next step is optional, and that is to reduce the star brightness with PixInsight Morphological Transformation.