Processing RAW using DxO - post your samples and tips - Part II

KoolKool wrote:

Do you have experience in processing Milky Way shot with DxO?

I have one and Deep Prime just not worked well.....

I've processed a lot of astrophotos using DxO Photolab 5, and generally find that Deep Prime does a great job at keeping detail while reducing the noise, even at high ISOs. The trick is to balance the sharpness of the photos with the Deep prime Luminance so that you have a very slight amount of grain in the image.

Here's an example of processing an image I took last June of the summer Milky Way, in the area of the 'summer triangle' with the bright stars Deneb (in Cygnus the swan), Vega (in Lyra) and Altair (in Aquila).

I used the Canon M6ii with the 22mm f2 lens, wide open at f2, and a 6 second exposure on a tripod at ISO 800. Much longer than that would have resulted in star 'trails' due to Earth's rotation. The 22mm f2 lens turns out to be a very good lens for astro, it's quite sharp although it does vignette quite a bit wide open, and brightest stars show some coma near the corners of the frame.

Here is the 'original' image without any processing except for lens corrections, DxO only converting it to a downsized 2160-pixel high JPG file. Standard noise reduction used with value of 40:

Here's the image processed. In order to really bring out the faint star clouds from the background noise, I applied an aggressive S-shaped custom tone curve (see the screen shot of the processing below) which has a steep incline in the shadows (high contrast) then a more gradual roll-off to the highlights. I also color balanced it to bring the background to a more neutral gray (or black) and applied Deep prime de-noise at a value of 40:

Here's the processing I did in DxO PL5, see the settings to the right:

Unfortunately, the location I was shooting from has some light pollution in the Eastern sky (down direction in the photo). I applied a mask to the 'polluted' region using multiple control points as shown, to mimic the 'glow' of light pollution. For the masked area, I reduced Exposure by -0.48 EV, increased highlights +20, increased midtones +46, and dropped shadows -24 units. This effectively applied another tone curve to the masked area which reduced the glow from light pollution in the sky background, while keeping the star clouds and stars at similar brightness to the rest of the frame.

Two satellites were caught by this exposure, they are slightly slanted vertical 'lines' in the upper middle part of the frame. Note how the tone brings them out along with the fainter stars in the processed image, compared to the unprocessed image.