How to process photos of night sky taken from smartphone

Question

I'm from Karachi, Pakistan. I'm very much interested in astrophotography but currently, being not much able to afford high level equipment, I try to work on my smartphone and learn from basic YouTube videos.

I somehow learnt to use pro mode of my Redmi Note 7 smartphone but still being a beginner, (definitely) making some mistakes. Also as I'm in residential area of very populated & happening city, there's too much light noise. I take pictures using pro mode which are somehow ok but needs processing. To process those images, I have to struggle as I don't know which part of image should be brighten and where should be noise removed from. I want to learn to process them (preferably on the very smartphone) using some good softwares e.g. SnapSeed etc

Here, I'm attaching few of the pictures taken by my phone in pro mode. I want to know how to process (which tools to use, which filters, etc. would be best if its Google's SnapSeed) also correct me if I'm mistaking something.

Answer 1

If you decide to edit RAW files (generated in PRO mode of Android phones) you can try those steps:

1. Fine-Tune White Balance.
2. Adjust Contrast and Exposure.
3. Apply Lens Corrections.
4. Dehaze.
5. Adjust Hue/Saturation/Luminance.
6. Fix Highlights and Shadows.
7. Apply Local Adjustments.
8. Reduce Noise and Sharpen the Photo.

More details about the process you can find here. In this manual is used Lightroom, but you can use RawTherapee, Darktable, GIMP (all free).

Answer 2

Here's some suggested post steps for such images:

levels: drag the left cut-off a bit to the middle of the range to darken the sky into black. Drag the right cut-off to the middle to brighten dim star.

noise: since you don't have any fine detail, you can get fairly aggressive on noise removal. The best (imho) would be to apply a 1-3px median filter on any shots of the night sky. If you have other detail like a city horizon, this can make them look cartoony, so apply the median filter then Edit>Fade Median Filter to ~50% to keep some of the improvement.

detail: if you have low noise but the stars are a little fuzzy, use unsharp mask to improve local contrast. Play around with different radii; while 0.4px-5px at 100% is typical, sometimes a huge value like 100px at a lower percent (ex 25%) really makes an image "pop". Watch out for undesired halos and tone it down until those artifacts just disappear.

Answer 3

Set your camera settings to manual (PRO) mode.

1 Set your shutter speed to minimum (e.g: 1 sec)

2 Set your ISO from 100-1600 (High ISO - more NOISE!)

3 Set Autofocus to Manual and move to infinity

4 VERY IMPORTANT : Put your phone on a tripod or somewhere to stand still

5 Set a timer like 5 second before to shot

6 You can use Photoshop on your phone to increase the shadows and add more light, also to remove noise and add sharpness.