Quick Start
For most uploads, use these defaults first:
- Object: choose Galaxy, Nebula, or Star Cluster based on the main target.
- Input: leave on Auto unless you know your file is already stretched.
- Stretch: leave on Standard for the first run.
- Color Separation: leave Nebula runs on Balanced first. Siril handles calibration; DeepSky only enhances color where nebula signal is present.
- Deconvolution: leave it off first, then test it on galaxies if you want sharper arms and dust lanes.
- Star Reduction: DeepSky automatically reduces stars so gas, dust, and galaxy structure stand out.
What The Settings Mean
Object
This chooses the finishing style. Galaxy processing protects broadband color, dust lanes, cores, and spiral texture. Nebula processing runs Siril color calibration and background extraction, then applies controlled DeepSky nebula color enhancement. Star Cluster processing keeps stars more natural and avoids heavy star removal.
Input
Auto lets DeepSky inspect the file histogram and choose the safest path. Use this first.
Linear tells DeepSky the file is raw or mostly unstretched. Use this if Auto is too gentle or the preview looks very dark before processing.
Pre-stretched tells DeepSky the image already has visible brightness/contrast. Use this if the result looks overexposed, washed out, or aggressively stretched.
Stretch
Subtle is safer for bright targets, already-bright files, star clusters, and cores that blow out easily.
Standard is the normal first try.
Aggressive is for very faint targets where the normal result is too dark or does not reveal enough gas or galaxy arms.
Color Separation
This Nebula-only setting controls DeepSky's masked color enhancement after Siril calibration. Natural is gentlest, Balanced is the default, and Strong pushes real red/orange and blue/cyan separation harder without coloring empty background.
Deconvolution
This optional galaxy-focused detail pass can sharpen spiral structure, dust lanes, and galaxy texture. It can also exaggerate grain on noisy data, so compare an unchecked run against a checked run before deciding.
Star Reduction
DeepSky automatically applies slight star reduction. It keeps the brighter stars, reduces the busy faint star field, and lets gas, dust, and galaxy structure stand out without making the image feel empty.
If The Image Looks Off
Too bright, blown out, or over-stretched
- Set Stretch to Subtle.
- Try Input as Pre-stretched if the file already looked bright before processing.
- For galaxies, keep the object set to Galaxy so the core is protected better.
Too dark or not enough faint detail
- Try Stretch as Aggressive.
- Make sure Input is Auto or Linear, not Pre-stretched.
- For faint nebulae, use Object: Nebula.
Galaxy looks soft or like a blob
- Use Object: Galaxy.
- Try deconvolution after you have a clean baseline, but turn it back off if the background gets grainy.
- Try Standard first, then Subtle if the core gets too bright.
Stars look weird, missing, or too reduced
- For star clusters, use Object: Star Cluster to preserve natural stars.
- Use Object: Galaxy for broadband galaxy fields and Object: Nebula for gas/dust targets.
- If stars still look too strong, try a more subtle stretch so the field does not get over-amplified.
Background is green, noisy, or muddy
- Leave Input on Auto first.
- Try Object: Nebula for emission targets and Object: Galaxy for broadband galaxy fields.
- If the image is already edited or exported from another app, try Pre-stretched.
Nebula gas disappears or looks too gray
- Use Object: Nebula.
- Try Stretch: Aggressive if the target is faint.
- Try Stretch: Subtle if bright areas are washing out the dust structure.
Star cluster looks unnatural
- Use Object: Star Cluster.
- Use Stretch: Subtle or Standard.
- Avoid galaxy settings unless the cluster is not the main target.
Downloads
PNG is best for sharing online and checking the result quickly.
TIFF is best if you want to continue editing in another program. It preserves more image data than PNG.
When You Need Help
If the output still looks wrong, send us the processed image and the original file. The fastest way for us to improve DeepSky is to see the exact file and the exact result that failed.