Comparison

OpenPPG vs HDRImage

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

Head to head
About

OpenPPG

Features
Read full description

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.

About

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.

Highlights
  • One-tap HDR processing
  • Enhances dark and dull photos
  • Creates vibrant and detailed images
  • Optimized for iOS devices
  • Improves social media sharing
Features
Read full description

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

OpenPPG4 screens
HDRImage3 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

ScorecardNo meaningful differences
OpenPPG versus HDRImage: the parameters behind the verdict, then further details
ParameterOpenPPGHDRImage
PriceFreeFree
Rating—5.0 (2 ratings) — better
Positive reviews—100.0% of reviews
Number of ratings—2 — better
Update frequencyMonthly—
AdsNoNo
In-app purchasesNoNo
Monetization—Free
DevicesiPhoneiPhone, iPad — better
Requires iOS17.617.0 — better
Further details — not scored
Size9 MB1 MB
Age rating4+4+
Developerresearch app天祺 王

In-app purchases

None

OpenPPG

No in-app purchases

None

HDRImage

No in-app purchases

Questions

Is OpenPPG free?
OpenPPG is free to download, with no in-app purchases.
Is HDRImage free?
HDRImage is free to download, with no in-app purchases.
Do OpenPPG or HDRImage have ads?
Neither OpenPPG nor HDRImage shows ads.

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