Comparison

AI CometStack vs AstroPile

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

AI CometStack

Features
Read full description

AI CometStack is a breakthrough comet alignment app designed specifically for mobile astrophotography workflows. Overcome the long-standing tradeoff of comet movement during long imaging sessions. Traditionally, you had to choose between sharp stars (streaked comet) or a sharp comet (trailed stars). AI CometStack solves this by eliminating complex desktop compositing and advanced scripting. Core Features Motion-Aware Stacking: Aligns the comet nucleus across time while preserving star geometry. Two-Path Automation: Integrates stars and comets separately, then blends them on-device. Batch Processing: Handles full-night capture sets with uniform parameters. Pro Format Support: Works natively with FITS, RAW, TIFF, PNG, and JPEG files. Mobile-First Flow: Real-time previews and guided steps built for iOS deep-sky sessions. Simple Workflow Import your exposure frames (or use the included sample files). Let the app automatically track and model comet motion. Validate and adjust the seamless background blend in real time. Export gallery-grade, press-ready images instantly from the field. Support & Feedback Questions, feedback, or need help? Contact us directly at ustransit74@gmail.com Privacy policy and term of use (EULA) is at https://deepskycolor.blogspot.com/2018/12/privacy-policy-for-deep-sky-color-app.html

About

AstroPile

Features
Read full description

One phone photo of the night sky is mostly noise. Stack a dozen shots of the same scene and the noise averages away while the faint detail stays — that is what astrophotographers call stacking. AstroPile does it on your phone, entirely offline: no network permission, and no photo is ever uploaded. WHAT MAKES IT DIFFERENT IS THAT IT TELLS YOU WHAT HAPPENED. Most stackers hand you one picture. If it came out smeared, you have no idea which frame ruined it. AstroPile gives every frame a report card: • how many stars were detected • how many matched the reference frame • the alignment residual, in pixels • a 0–100 quality score Frames that could not be aligned say why — too few stars, too bright, no matching star pattern, residual too large, different pixel size — plus one line on what to change. Untick it and stack again. HOW IT WORKS 1. Pick two or more shots of the same scene 2. Choose the reference frame (the first one by default) 3. Start stacking — you can stop at any point 4. Drag black point, brightness and saturation; the preview updates live 5. Save to Photos or Share — the export is full resolution HOW IT ALIGNS Not by corner detection: stars look identical to each other, so feature matching does not work on a star field. AstroPile matches asterisms — the shape of the triangle each star forms with its neighbours — then uses RANSAC to throw out the false pairs and solves for shift, rotation and scale. This is the standard approach for registering star fields with no WCS information. DETAILS THAT MATTER • Reads EXIF on import and flags frames shot with different exposure settings than the rest • Frames with a different pixel size are marked in red instead of quietly ruining the stack • Combines in horizontal bands, so even a few dozen full-resolution frames will not exhaust memory • Scratch files are deleted when the run ends, and swept again on the next launch FREE Up to 6 frames per stack, mean stacking, full-resolution export, and the full per-frame alignment report. No ads, no watermark, no account. ASTROPILE PRO (a one-time purchase, not a subscription) • Up to 32 frames per stack • Median stacking — aircraft, satellite trails and hot pixels drop out on their own • Remembers your stacking mode and working resolution PRIVACY The app requests no network permission and contains no analytics or advertising SDK. Photos are read and processed on this device only; the finished picture leaves the app only when you save or share it. CREDITS Star-field registration follows astroalign (MIT, Ā© 2016 Martin Beroiz), frame stacking follows OpenSkyStacker (MIT, Ā© 2017 Benjamin Schubert), and the star-sharpness check follows the published design of astra_lite (MIT, Ā© 2023 Denis Artyomov). This app is an independent Dart implementation and copies none of their code.

Screenshots

AI CometStack2 screens
AstroPile4 screens

Verdict

The call

The clearest difference is iOS requirement: AstroPile at 15.0 against AI CometStack's 17.0. On price, ads, in-app purchases and device support there is nothing between them.

Scored on Price Ā· Rating Ā· Positive reviews Ā· Number of ratings Ā· Update frequency Ā· Ads Ā· In-app purchases Ā· Monetization Ā· Best chart rank Ā· Devices Ā· Requires iOS

CostPrice Ā· In-app purchases Ā· Ads Ā· Monetization

Both are free to download. AI CometStack sells 1 in-app purchase, starting at $9.99 per year and AstroPile sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Scorecard1 real difference Ā· 4 level
AI CometStack versus AstroPile: the parameters behind the verdict, then further details
ParameterAI CometStackAstroPile
PriceFreeFree
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPadiPhone, iPod
Requires iOS17.015.0 — better
Further details — not scored
Size105 MB20 MB
Age rating4+4+
Developeryong chong lohtao wen

In-app purchases

1 purchases

AI CometStack

Subscriptions1
  • Yearly Subscription$9.991 Year
1 purchases

AstroPile

One-time1
  • AstroPile Pro$3.99

Questions

Is AI CometStack free?
AI CometStack is free to download, with in-app purchases available.
Is AstroPile free?
AstroPile is free to download, with in-app purchases available.
Do AI CometStack or AstroPile have ads?
Neither AI CometStack nor AstroPile shows ads.

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