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Project Overview: I am looking for a developer or team to build a dual-mode educational grading system. The system consists of: An iOS App: Capable of real-time scanning and grading of both standard OMR bubble sheets AND unique orientation-based cards (Plickers-style). A PHP Web Backend: A tool to generate customized PDF test sheets and student cards using Chromium (via Spatie/Browsershot). Privacy is paramount. All student scanning and grading must occur on-device to ensure data security. Module 1: The iOS App (Swift/SwiftUI) The app must feature a toggle or auto-detection to switch between two modes: Mode A: OMR Bubble Sheets: Detects standard multiple-choice grids. Real-time detection of "filled" vs. "empty" bubbles using local image thresholding. Mode B: Plickers-Style Cards: Detects unique geometric shapes (markers) assigned to each student. Grading is based on the orientation of the card (A, B, C, or D at the top). Must support scanning multiple cards in a single camera frame (e.g., scanning a whole classroom). Technical Requirements (iOS): Engine: Use Apple’s Vision Framework and Core Image for high-speed, real-time processing. Local Processing: No images should be sent to a server for grading. All logic must be local. Database: Use CoreData or SQLite with encryption to store student rosters and scores. Export: Generate CSV/Excel reports locally from the app. Module 2: PDF Generation Engine (PHP/Chromium) I need a system to generate the physical papers that the app will scan. Technology: PHP 8.x with Spatie/Browsershot (Headless Chromium). OMR Generator: Dynamically generate bubble sheets based on the number of questions (e.g., 10, 20, 50, 100 questions). Plickers Card Generator: Generate a unique set of cards (40–60 unique patterns) with student names printed on the back/corners. Layout: High-precision CSS layout to ensure that "anchor points" (the black squares in the corners) are perfectly placed for the iOS camera to find the grid. Output: High-quality, print-ready PDFs. Module 3: Privacy & Security Zero-Cloud Grading: The server only generates the PDFs. It should never see the students' filled-in answers. GDPR/FERPA Ready: The app must not include third-party trackers. Local Encryption: Student data stored on the iPhone must be protected via the iOS Secure Enclave/Keychain. Specific Deliverables: iOS Source Code: Fully documented Swift code. PHP Script/Backend: A web-based interface where I can input questions or student lists and download the generated PDFs. PDF Samples: Set of 5 sample OMR templates and 1 set of 40 unique Plickers cards. Hardware Calibration: The scanner must be optimized for different iPhone models (adjusting for focal length/distortions). Developer Requirements: Expertise in Computer Vision (Vision Framework, OpenCV, or AVFoundation). Strong PHP/Laravel skills with experience in Puppeteer/Chromium/Browsershot. Experience with Real-time Camera Overlays (drawing bounding boxes and scores over the live feed). Ability to demonstrate previous OMR or QR-related scanning projects. Application Instructions: Please start your proposal with the word "HYBRID". In your proposal, please answer: How will you ensure the OMR grid detection remains accurate if the teacher holds the phone at an angle? Have you used Browsershot/Chromium for high-precision print layouts before?
Project ID: 40348289
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Active 11 days ago
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34 freelancers are bidding on average $98 USD for this job

Hello! I am excited about the opportunity to work on your project involving the development of a dual-mode educational grading system. The project entails creating an iOS App capable of real-time scanning and grading of OMR bubble sheets and orientation-based cards, along with a PHP Web Backend for generating customized PDF test sheets and student cards. Privacy and data security are top priorities, ensuring all scanning and grading processes occur on-device. The iOS App will be built using Swift/SwiftUI and will feature two modes for different grading methods, with technical requirements focusing on using Apple’s Vision Framework and Core Image for efficient processing. Regards, Yogesh Kumar
$10 USD in 8 days
8.3
8.3

Hi HYBRID This is exactly the kind of build I enjoy because it combines on-device computer vision, privacy-first architecture, and a precise PDF generation pipeline that has to work reliably together as one system. I have experience with Swift/SwiftUI, AVFoundation, Vision, Core Image, secure local storage, and PHP-based document generation workflows, including high-accuracy layouts rendered through Chromium for print-ready output. The biggest technical challenge here is keeping OMR and card detection stable when the phone is tilted or the sheet is slightly distorted, so I would use corner-anchor detection, perspective correction, lens calibration profiles per device class, and normalized sampling regions before any bubble or orientation scoring happens. For the Plickers-style mode, I would build the scanner to detect multiple markers in a single frame, estimate each card’s pose and top-edge orientation locally, then map that result directly to the student roster stored in encrypted local storage without sending images to a server. On the PDF side, I have worked with Chromium-based rendering for precise print layouts, and I would use that approach here to generate OMR sheets and unique student cards with fixed anchor geometry, repeatable CSS positioning, and print-safe output that aligns with the iPhone scanning logic. Best regards, Hercules
$30 USD in 7 days
6.6
6.6

Hybrid I have read your requirements and I am sure I will be able to help you. Python backend will be used for OMR reader. Please message me so that we will have detail technical discussion. I have 9+ years of combined experience in Mobile Application development, Website development, Desktop application development, 3rd party Artificial Intelligence api, AR/ VR, Chatbot, Blockchain- Cryptocurrency, CRM & ERP, Game Development and any other Software development. I am having expertise in Native on Android Java, kotlin and IOS Swift, and For Hybrid Cross platform on Flutter Dart & React- Native, and for web and backend on react js and node js, Python Django , java spring boot and php CodeIgniter mvc. Please consider me and initiate a chat for further detailed discussion. Regards, Anju
$450 USD in 15 days
6.6
6.6

HYBRID. As an experienced developer, I understand the paramount importance of privacy, security, and on-device data processing in your project - and that's exactly my area of expertise. In addition to my iOS capabilities, I boast advanced proficiency in PHP 8.x, Laravel, and Spatie/Browsershot which are essential for the PDF generation engine you need. I've used Puppeteer/Chromium before to generate high-precision print layouts - ensuring that the "anchor points" are perfectly placed for optimal iOS camera capture. Drawing bounding boxes and scores over live feeds? To assure you further on printing experience with Browsershot/Chromium; yes, I have worked extensively on high-precision print layouts with them while developing advanced web-to-pdf conversion schemes; so there's no doubt about ensuring perfection around 'anchor points' placement. Working together on this project means amalgamating my prowess with your vision of a zero-cloud+highly secure hybrid platform for assessment control delivering accuracy, speed & control.
$20 USD in 7 days
5.6
5.6

This is exactly the kind of system I enjoy building—where computer vision, performance, and privacy all matter together. For angled OMR detection, I’ll use perspective correction with Apple Vision + Core Image (homography transform + anchor point detection). This ensures the grid is normalized before evaluation, so results stay accurate even with camera tilt or distortion. For the PDF engine, yes—I’ve worked with Chromium via Browsershot to generate pixel-perfect print layouts. I’ll lock anchor points using precise CSS/mm units so scanning remains consistent across devices. What makes my approach different: I focus heavily on real-time speed, clean architecture, and on-device security (no shortcuts with cloud processing). Let’s connect and discuss your exact workflow—I can suggest optimizations that will save you time and cost. Final price can be confirmed after a quick discussion.
$15 USD in 3 days
6.1
6.1

HYBRID" With nearly a decade of experience in both iOS and PHP development, I bring unmatched proficiency to your Hybrid Educational Grading System project. I have hands-on expertise in Swift and SwiftUI, having built several real-time scanning and grading apps. Your project's need for on-device scanning and local processing align perfectly with my skills and beliefs on privacy protection. I emphasize using Apple's Vision Framework and Core Image to ensure the highest level of security, integrating them seamlessly with CoreData or SQLite for encrypted storage. I have done similar work on local storage before so you can be assured your students' data will not leave their respective devices. Furthermore, your requirement for a PDF Generation Engine highlights another of my key competencies. My sound knowledge in PHP combined with extensive usage of Spatie/Browsershot (Headless Chromium) demonstrates my qualification to produce high-precision layouts for perfect anchor point placement needed for camera grid detection. Also, having produced various high-quality prints through this process, I am confident that the generated PDFs will meet your requirements. In fact, I offer three months of free support post-delivery to guarantee absolute satisfaction with the developed web backend interface you requested. Lastly, your focus on Privacy & Security is paramount and brings me comfort since it is an area where I thrive. With GDPR/FERPA care major focus in Your project
$120 USD in 7 days
5.6
5.6

HYBRID educational grading systems require a delicate balance of technology and pedagogy. I read your project details regarding the development of a dual-mode educational grading system, and I am confident that I can deliver a high-performance application that meets your requirements. My approach involves utilizing Apple's Vision Framework and Core Image for the iOS app, ensuring high-speed, real-time processing of OMR bubble sheets and Plickers-style cards. For the PHP web backend, I will leverage PHP 8.x with Spatie/Browsershot (Headless Chromium) to generate customized PDF test sheets and student cards. To ensure privacy and security, all student scanning and grading will occur on-device, with local encryption using the iOS Secure Enclave/Keychain. To address your concerns, I will implement a robust OMR grid detection algorithm that can handle angled phone positions by using perspective correction techniques. I have experience with Browsershot/Chromium for high-precision print layouts, which will enable me to generate accurate and print-ready PDFs. As an expert in computer vision and PHP development, I am well-equipped to handle the technical requirements of this project. My previous experience with real-time camera overlays and OMR/QR-related scanning projects has prepared me to tackle the challenges of this project. Let's discuss the features you need in the MVP, including the iOS app, PHP web backend, and PDF generation engine.
$300 USD in 5 days
5.0
5.0

HYBRID, Greetings I'm a senior Full Stack developer with 7 years and here is my approach: 1. Build iOS app using Swift with Vision Framework and AVFoundation for real-time camera-based scanning and grading 2. Implement dual-mode detection system for OMR bubble sheets and Plickers-style orientation cards with high accuracy 3. Develop real-time image processing pipeline using Core Image 4. Set up local encrypted database to securely store student data and results with zero cloud dependency Build PHP backend using Browsershot to generate high-precision OMR sheets and unique student cards in print-ready PDF format 1. How will you ensure the OMR grid detection remains accurate if the teacher holds the phone at an angle? I will use rectangle detection and perspective correction to normalize the captured sheet into a top-down aligned view. Anchor points will be used to precisely map the grid, followed by adaptive thresholding to reliably detect filled bubbles under different lighting and angles. This ensures consistent accuracy even with tilt or distortion. 2. Have you used Browsershot/Chromium for high-precision print layouts before? Yes, I have experience using Browsershot with headless Chromium to generate pixel-perfect PDFs. I use structured HTML templates with precise CSS to ensure accurate alignment for print, including fixed anchor points and scalable layouts for dynamic content like OMR sheets and card patterns. Looking forward to your response.
$10 USD in 7 days
4.4
4.4

Hello Dear, I’m an experienced full-stack and mobile developer with 10+ years of expertise in computer vision and secure application development. I understand you need a dual-mode grading system with on-device OMR and Plickers-style scanning plus a PHP-based PDF generation engine. I’ve worked on similar real-time scanning and document-generation systems using Vision Framework and Chromium tools. For angled OMR accuracy, I’ll use perspective correction (homography), anchor-point detection, and adaptive thresholding to normalize the grid before analysis. Yes, I’ve used Browsershot/Chromium for precise PDF layouts with pixel-perfect positioning. My skills in Swift, Vision, PHP, and secure local storage ensure a reliable, privacy-first solution. Let’s discuss implementation details. Best regards, Md Ruhul
$30 USD in 2 days
5.5
5.5

HYBRID & Must check our detailed proposal please. Relevant portfolio available to share - just drop a message and we'll send it your way. We are a cross-disciplinary team specializing in iOS computer vision and PHP/Chromium PDF generation. We can build your dual-mode educational grading system with on-device OMR and Plickers-style scanning and a secure PDF generation backend. iOS App (Swift/SwiftUI): Real-time OMR bubble detection and Plickers-style card orientation using Apple Vision & Core Image. Multi-card scanning per frame, bounding boxes, and live score overlays. Local data storage with CoreData/SQLite encryption, CSV/Excel export, zero-cloud grading. Accuracy maintained via perspective correction and adaptive thresholding for angled phone positions. PHP Backend (Chromium/Spatie Browsershot): Dynamic PDF generation for OMR sheets (10–100 questions) and 40–60 unique Plickers cards. High-precision CSS layout ensuring anchor points align for reliable scanning. Print-ready PDFs delivered via secure web interface. We prioritize privacy (GDPR/FERPA ready) and optimized performance across iPhone models. We have previous experience with high-precision PDF layouts and computer vision scanning projects, and can provide sample code. We can deliver iOS source code, PHP backend scripts, PDF samples, and hardware calibration guidance. Timeline and milestones are flexible and aligned with your goals.
$750 USD in 20 days
4.0
4.0

Hi You are looking for a developer/team to build a dual-mode educational grading system with an iOS app for real-time OMR and Plickers-style scanning, plus a PHP backend for PDF generation. Here is my plan I will develop the iOS app in Swift/SwiftUI using Apple’s Vision framework and Core Image to detect filled bubbles and orientation-based cards in real time, with local processing only. CoreData/SQLite with encryption will store rosters and scores, and exports will be CSV/Excel. The PHP backend using Spatie/Browsershot will generate precise, print-ready OMR sheets and unique Plickers cards. Admin interface will allow inputting questions and student lists while ensuring alignment for scanning accuracy. To proceed kindly let me know the following How will you ensure the OMR grid detection remains accurate if the teacher holds the phone at an angle? Have you used Browsershot/Chromium for high-precision print layouts before? Do you need dynamic scaling for varying classroom lighting conditions or just standard indoor lighting? i do have more than 7 years of experience and would glad to help you in building this secure, dual-mode grading system with real-time scanning, high-precision PDF generation, and local-only data handling. I am available to discuss milestones and start immediately. Thank you
$20 USD in 7 days
3.8
3.8

HYBRID Your project requires a sophisticated dual-mode educational grading system that prioritizes accuracy and privacy, which are critical in an academic setting. I have over 12 years of experience as a Full-Stack Developer with expertise in both iOS development and PHP backend systems. To ensure OMR grid detection remains accurate when the device is held at an angle, I would implement perspective correction algorithms within Apple’s Vision Framework. This will help account for varying angles and maintain reliable detection of filled bubbles. I have previously utilized Browsershot/Chromium for generating high-precision print layouts, ensuring that all elements align perfectly for scanning purposes. Furthermore, leveraging technologies like Swift/SwiftUI for the iOS app and PHP with Spatie/Browsershot will streamline both the front-end and back-end processes effectively. Could you please clarify how many different question sets you envision needing generated in the PDF output? Looking forward to your response!
$30 USD in 7 days
3.6
3.6

HYBRID I’ll build this as a calibrated, on-device vision system so grading stays accurate and private in real classroom conditions. For angled OMR detection, I’ll use Apple Vision for rectangle detection + perspective correction (homography) to normalize the sheet before processing. Then adaptive thresholding ensures reliable bubble detection even with lighting variations, while anchor markers lock grid alignment. For Plickers-style cards, I’ll implement multi-marker detection with orientation tracking, allowing multiple students to be scanned in one frame with real-time overlays via AVFoundation. All processing stays on-device. Data will be stored using encrypted CoreData/SQLite with Keychain, and reports (CSV/Excel) generated locally. On the backend, I’ve handled Chromium/Browsershot-based PDF generation with pixel-perfect CSS layouts—ensuring anchor points align exactly with the scanning engine. This will be built as a stable vision pipeline, not a fragile scanner. If you want accuracy across devices and zero compromise on privacy, I can start immediately. Best; Zaman
$20 USD in 7 days
3.1
3.1

Hey , I just went through your job description and noticed you need someone skilled in iPhone, Mobile App Development, SQLite, Computer Vision, OpenCV, iOS Development, PHP and Objective C. That’s right up my alley. You can check my profile —I’m Software engineer working at large-scale apps as a lead developer with U.S. and European teams. I’ve handled several projects using these exact tools and technologies. Before we proceed, I’d like to clarify a few things: Are these all the project requirements or is there more to it? Do you already have any work done, or will this start from scratch? What’s your preferred deadline for completion? Why Work With Me? 1) Over 230 successful projects completed. 2) I have not received a single bad feedback since the last 5-6 years. 3) You will find 5 star feedback on the last 100+ major projects which shows my clients are happy with my work. 4) Long-term track record of happy clients and repeat work. I prioritize quality, deadlines, and clear communication. Availability: 9am – 9pm Eastern Time (Full-time freelancer) I can share recent examples of similar projects in chat. Let’s connect and discuss your vision in detail. Kind Regards, Imran Haider
$10 USD in 2 days
2.4
2.4

Hi, I can easily DO your work IN 24 HOURS, DM me now to get started, PRICE NEGOTIABLE 100% Work satisfaction is provided
$20 USD in 1 day
1.9
1.9

HYBRID I totally understand your requirement—building a privacy-first dual-mode grading system with real-time on-device OMR + Plickers-style detection and a precise PDF generation backend. I’ve delivered a similar solution where we built an iOS Vision-based scanner for MCQ sheets (adaptive thresholding + perspective correction) and a PHP (Browsershot) engine for print-perfect templates with anchor alignment. The system handled multi-sheet detection and produced accurate results even under varied lighting and angles. For OMR accuracy at angles, I’ll use Vision’s rectangle detection + homography (perspective transform) to normalize the grid before bubble analysis, combined with adaptive thresholding and contour validation. For Plickers-style cards, I’ll implement marker detection with orientation classification and multi-object tracking in a single frame. All grading remains strictly on-device with encrypted storage (Keychain/CoreData). Yes, I’ve used Browsershot/Chromium for high-precision layouts—ensuring consistent DPI, margins, and anchor positioning for reliable scanning. A few quick questions: 1. Target iPhone models range for calibration? 2. Max students/cards per scan frame expected? 3. Any specific export format beyond CSV/Excel (e.g., LMS integration)? Let me know when you’re available to discuss this further I’d be happy to walk you through my approach or showcase examples relevant to this project. Looking forward to hearing from you! Best regards, Mulayam
$20 USD in 7 days
1.2
1.2

⚠️No results no payment ⚠️ Your requirement for real-time, on-device OMR and Plickers-style grading with strict privacy measures is impressive—you’re in good luck! Leveraging my expertise with Apple’s Vision Framework and Core Image, I’ll deliver an adaptive scanning engine that compensates for angles and lighting variances, ensuring consistent accuracy without cloud dependency. Deliverables: - Fully documented Swift iOS app source code with dual-mode scanning - PHP backend for dynamic PDF generation via Spatie/Browsershot - Sample PDFs with precision layout for reliable scanning - Encrypted local data storage with GDPR-compliant security - Hardware calibration optimized for multiple iPhone models I would like to discuss more about the project; worst case, you lose nothing. Best case, you walk away with a free consultation and real clarity. Looking forward to discussing your project in detail. Kind Regards Shafeeq
$14 USD in 14 days
0.0
0.0

"Choosing a developer for your Hybrid Educational Grading System isn't an easy task, but let me make it simple for you. I fully comprehend the project's intricate requirements and have tackled similar challenges before. My extensive knowledge in computer vision, `Vision Framework`, and `Core Image` combined with my experience with `OpenCV` and `AVFoundation` equip me to tackle any obstacle, including ensuring the OMR grid detection remains accurate at any angle." "In addition to my strong back-end skills, my expertise in front-end technologies such as `Vue.js` and `React` will be invaluable in creating a seamless user experience across both the iOS app and the PHP web backend. You’ll also benefit from my understanding of privacy protection - essential for a project that deals with sensitive student data like this one - thanks to my previous work with GDPR/FERPA compliant applications." "Moreover, I have significant experience using tools like `Spatie/Browsershot` to generate high-quality PDFs, aligning perfectly with your needs. This interdisciplinary skill set - deep understanding of both iOS development and highly-precise print layouts - is precisely what sets me apart from other freelancers. I am confident that I can deliver beyond your expectations on every front - architecture, design, functionality, security, and scalability of your Hybrid Educational Grading System."
$20 USD in 7 days
0.0
0.0

HYBRID Hi, This is exactly the type of system I’ve worked on, combining computer vision with secure, on-device processing and precise PDF generation. I’ve built similar scanning solutions using Vision Framework + OpenCV concepts (OMR-style grading, QR/marker detection), and also implemented high-accuracy PDF generation using Browsershot/Chromium in PHP (including pixel-perfect layouts for print alignment). 1. OMR accuracy at angles I handle this using perspective correction (homography). The app detects anchor points (corner markers), then normalizes the sheet to a flat top-down view before processing bubbles. This ensures consistent detection even with tilt, rotation, or slight distortion. 2. Browsershot experience Yes, I’ve used Browsershot to generate print-ready PDFs with strict positioning (including grids, labels, and markers). I ensure accuracy by controlling DPI, margins, and CSS absolute positioning, and validating outputs against real print tests. Relevant experience OMR-style exam grading app with real-time camera overlay Marker-based detection systems (similar to Plickers concept) Fintech + data-sensitive apps (strong focus on privacy & local processing) PDF engines for invoices/reports (Crater, Ninja Invoice-level systems) Let’s discuss your timeline and I can propose a clear implementation plan. Best regards
$20 USD in 7 days
0.0
0.0

Hi, This is Gene from Luxembourg. I understand you need a privacy-first iOS app that can scan both OMR sheets and orientation-based cards in real time, along with a PHP system to generate precise printable templates. I’ll build the scanning engine using Vision + Core Image with perspective correction and adaptive thresholding, and set up the PHP side with Browsershot to produce pixel-accurate PDFs aligned for reliable detection. I’ve worked on camera-based scanning apps and document detection before, including real-time overlays and local processing, and I’ve also used Chromium-based rendering for generating print-ready layouts with strict positioning requirements. For your questions: I’ll handle angled scanning using homography correction and anchor-point detection to normalize the grid before grading, and yes, I’ve used Browsershot/Chromium to generate high-precision PDFs with consistent layout across devices and printers. For the Plickers-style detection, do you already have a defined marker set or should I design and validate a new one optimized for Vision-based recognition? Happy to discuss further and share relevant work.
$20 USD in 2 days
0.0
0.0

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