OpenPPG vs HDRImage
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
OpenPPG
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OpenPPG is a free, research-oriented iOS application designed to close the gap in accessible and transparent PPG data acquisition. Built by researchers for researchers, it enables recording of raw, high-quality photoplethysmography (PPG) signals directly from the smartphone camera, with full export for scientific analysis. Key Features • Raw signal access – capture unprocessed PPG waveforms with complete control over export (CSV format). • Flexible preprocessing – raw signals, basic and advanced filtering, signal quality assessment or fully calculated metrics in one app to enhance your research • Feature extraction – access directly over 11 automatically calculated temporal and morphological metrics without need for advanced signal processing • Metadata & annotations – mark events while taking measurements in real time and customise forms to fit your study protocol • Explainable pipeline – reproducible acquisition process with transparent documentation to ensure research reliability. Why OpenPPG? Most mobile tools restrict access to raw data, hide acquisition details, or require payment. OpenPPG removes these barriers by providing a free, standardised, and reproducible way to acquire PPG signals. It supports innovation in signal processing, machine learning, and digital biomarker discovery. Important: OpenPPG is intended solely for research purposes. It is not a medical device and must not be used for diagnosis, treatment, or patient self-monitoring.
HDRImage
Transform your photos with advanced High Dynamic Range (HDR) processing. This app enhances dark or dull images, making them vibrant and detailed with a single tap. Achieve professional-looking results for social media sharing.
- One-tap HDR processing
- Enhances dark and dull photos
- Creates vibrant and detailed images
- Optimized for iOS devices
- Improves social media sharing
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HDRImage: THE ULTIMATE PHOTO SUPERPOWER! Your photos have been LIVING IN THE SHADOWS for too long. IT’S TIME TO UNLEASH THEIR TRUE FORM! With HDRImage, even the lamest, darkest pic becomes a VIBRANT, EYE-MELTING, NEXT-LEVEL MASTERPIECE! WHY SETTLE FOR NORMAL WHEN YOU CAN GO SUPER SAIYAN? - ONE-TAP HDR GOD MODE – No training, no effort—just INSTANT GLOW-UP! - MADE FOR iOS FLEXING – Your iPhone screen won’t know what hit it! - DOMINATE SOCIAL MEDIA – More likes? More shares? MORE POWER! - NO OVEREXPOSURE, ONLY OVERPERFECTION – Our tech keeps it crisp, not cursed. DOWNLOAD NOW AND ASCEND TO PHOTO LEGEND STATUS! THE LIGHT AWAITS!
Screenshots
Verdict
OpenPPG and HDRImage are too close to call on the numbers: across 5 compared parameters — price, ads, in-app purchases and device support among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.
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. Neither carries in-app purchases, so what you see is what you pay.
| Parameter | OpenPPG | HDRImage |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (2 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | — | 2 — better |
| Update frequency | Monthly | — |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | — | Free |
| Devices | iPhone | iPhone, iPad — better |
| Requires iOS | 17.6 | 17.0 — better |
| Further details — not scored | ||
| Size | 9 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | research app | 天祺 王 |
In-app purchases
OpenPPG
No in-app purchases
HDRImage
No in-app purchases









