RoboTou Stacker vs Sharp
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
RoboTou Stacker
Combine multiple photos directly on your device for enhanced results. This app offers automatic masking and alignment for various photography needs, including starry skies and light trails. Process your images locally without needing an account or cloud sync.
- On-device image stacking
- Automatic masking and alignment
- Starry sky stacking
- Star trail stacking
- Car-light trail stacking
- Local preview generation
- Export to Photos
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RoboTou Stacker brings precision image stacking and on-device AI star removal to iPhone and iPad. Choose a workflow for your photography: • Starry Sky Stack — Align and combine night-sky photos for cleaner, more detailed results. • Landscape Stack — Reduce noise and improve landscape images through multi-frame stacking. • Star & Light Trails — Create star-trail and car-light-trail images. • Star Trail Pro — Produce advanced star-trail results with additional processing options. • AI Star Removal — Remove stars from a single image using an on-device Core ML model. KEY FEATURES • Import images from Photos or Files • Automatic masking and image alignment • 4K and 1080p output resolution options • Local preview generation and project management • Export finished images back to Photos • On-device processing—your source images do not need to be uploaded ROBOTOU PRO Landscape Stack and Star & Light Trails remain available for free. RoboTou Pro unlocks Starry Sky Stack, Star Trail Pro, and AI Star Removal through an annual subscription or a one-time lifetime purchase. Privacy Policy: https://www.robotou.cn/robotou-stacker-ios-privacy/ Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Sharp
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Shoot the same thing more than once, and Sharp puts the shots together. Six tools, one engine. Nothing here edits a single photograph — everything here takes many frames of the same scene and gives back one picture. FOCUS — sharp from front to back A lens holds one plane in focus, and close up that plane is thinner than the subject. Move the focus between frames and Sharp takes every part of the result from the frame that has it sharpest. Not sure how wide its detail size should be? Choose by Eye stacks a piece of your bracket at four widths, side by side, so you can see which one has no halo. CLEAN — less noise, and long-exposure water Noise is different in every frame and the subject is not, so averaging frames takes it down by the square root of how many you shot: four halve it, sixteen quarter it. Water and cloud move between frames and average into smoothness, while everything that held still stays sharp. VANISH — the people walk out of the picture Take a dozen frames a few seconds apart while the square empties and fills. At each pixel Sharp keeps the frames that agree and throws out the ones that do not, then averages what is left — whoever was walking through is gone, and the noise goes with them. TRAILS — every place the light went A hundred short exposures of a night sky, a torch drawing, headlights on a bend. Sharp keeps the brightest frame at each pixel, so every mark the light made is in the picture and the sky stays as dark as one frame had it. Or keep the darkest instead, and take the passing lights out. BLEND — the shadows and the highlights both An exposure bracket, darker and brighter, into one picture: the sky from the dark frame, the shadows from the bright one, blended without a seam and with no curve to set. PICK — the sharpest frame of the burst Twenty handheld frames, one of them caught between heartbeats. Sharp hands back the one that won, exactly as it came off the camera. BUILT FOR LARGE SETS • Camera RAW, HEIC, JPEG, TIFF and PNG, read straight from Files or Photos • Frames are read a strip at a time, so memory does not grow with the number of frames • Alignment that covers focus breathing, drift and a rolled wrist, and checks its own work • Compare the result with any single frame at exactly the same zoom, beside a map of how each pixel was decided PAINT IT BACK Every one of these tools is a guess made a pixel at a time. Choose the frame that has that part right and paint it back over the result — one finger paints, two move the picture, an Apple Pencil presses harder for more. The repair is re-applied to the 16-bit file at full depth. FREE, AND THEN ONE PAYMENT All six tools run on up to 12 frames free, at full quality: the same alignment, the same merges, the same speed, the same RAW support, and a full-resolution JPEG with no watermark. Nothing about how good the picture is has been held back. The $9.99 unlock adds: • Unlimited frames, for every tool • The retouch brush, with retouches you can reopen and change • 16-bit TIFF, the maps, and every frame aligned for Helicon, Zerene or Photoshop • Every bracket kept as a project, with its settings and its result • Batches of projects run one after another, and long brackets stacked in slabs One payment, shared with your family. No subscription, no account, and not a timed trial. NOTHING LEAVES YOUR DEVICE No analytics, no tracking, no server, and no network of its own. Your photographs are read where they are, and the only thing that goes anywhere is what you share yourself.
Screenshots
Verdict
The clearest difference is update cadence: RoboTou Stacker at every 5 days against Sharp's fortnightly. RoboTou Stacker also leads on iOS requirement (17.0 vs 27.0). On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. RoboTou Stacker sells 2 in-app purchases, starting at $5.00 per year and Sharp sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
RoboTou Stacker ships an update every 5 days, Sharp fortnightly. The most recent releases landed on September 29, 2026 and October 13, 2026 respectively.
| Parameter | RoboTou Stacker | Sharp |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 5 days — better | Fortnightly |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 17.0 — better | 27.0 |
| Further details — not scored | ||
| Size | 88 MB | 3 MB |
| Age rating | 4+ | 4+ |
| Developer | 振国 吴 | Pablo Miranda |
In-app purchases
RoboTou Stacker
- RoboTou Stacker Pro Annual$5.001 Year
- RoboTou Stacker Pro Lifetime$39.99
Sharp
- Unlock Sharp 12$9.99









