OMR Sheet Scanner (Grade Bubble Sheets with a Phone Camera)

About the OMR Sheet Scanner (Grade Bubble Sheets with a Phone Camera)

Mark multiple-choice tests without an OMR machine. Print MySmartCoPilot’s answer sheet (60, 100 or 200 questions), let the class fill in the bubbles, then scan the sheets with your phone’s camera, from photos, or from a PDF made by a scanner. Each sheet is straightened, its bubbles are measured, and its roll number and test version are read; marks that are too light, or look half-erased, are set aside for you to check on screen before anything is final.

Type the answer key — or scan one sheet filled in with the right answers — choose the marking (marks for a right answer, marks taken off for a wrong one, partial marks for questions with several right options), and the results table fills in as you scan. Download it as CSV or as an Excel workbook, with an item analysis that shows which questions were too easy or too hard, which ones did not separate stronger from weaker students, and which wrong options nobody chose. Photos and PDFs are read on this device and never uploaded.

Common uses

• Class tests, unit tests and mock exams in schools and coaching centres.
• Entrance-exam practice with negative marking, such as +4 / −1.
• Quizzes in training sessions, where a phone is the only scanner at hand.
• Checking which questions of a question bank work before using them again.

How the sheets are read

• Finding the sheet: dark pixels are found against their own neighbourhood (so shadows and uneven light do not matter), and the six solid black squares are picked out by size and shape. The four corners give the perspective; the two middle squares let the top and bottom halves be corrected separately, which follows a page that is not lying flat. A solid bar at the top left tells which way up the sheet is, so sideways and upside-down photos are fine.
• Measuring the bubbles: each block of five rows is lined up on its printed circles, then every bubble’s inside is compared with the paper just around it and with the black of the corner squares — 0 % is empty, 100 % as dark as the squares.
• Deciding: the cut between empty and filled is worked out for each sheet from all its bubbles (Otsu’s method), so a class that uses light pencil is read as well as one that uses pen. Bubbles close to the cut, and second marks much lighter than the first (a change that was not fully erased), go to To check.
• Roll number and version: eight digit columns and one A–D column, read the same way. The layout is printed in four small squares at the top right, so the scanner knows which sheet it is looking at.

The tool reads only sheets printed from this page: other OMR sheets have their marks in other places.

Marking

• Right / wrong / blank: marks for a right answer, marks taken off for a wrong one (negative marking), nothing for a blank.
• Double marks on a question with one right answer count as wrong, or as zero.
• Several right options: a key such as (AC) needs both. With partial marks on, filling only some of the right options earns that share of the marks; any wrong option earns the wrong-answer marks.
• Either is right: (A/C) accepts A or C.
• Dropped and bonus questions: - leaves a question out of the total; * gives everyone its marks.
• Versions: if the test has versions A–D with the questions in different orders, give each version its key; a sheet uses the key of the version its student filled, or the key for all versions.
• Answer key from a sheet: fill in one sheet with the right answers, scan it, and press Use this sheet as the answer key in its review — that sheet is then not counted as a student.

Item analysis

For every question, from the sheets marked with the same key:

• Difficulty: the share of students who answered it right. Questions almost everyone gets right (90 % and more) or almost nobody does (20 % and less) are pointed out.
• Discrimination: the share right among the top 27 % of the class (by total score) minus the share right among the bottom 27 % — Kelley’s classic groups. Below 0.2 a question does little to separate stronger from weaker students; below zero, more weak students got it right than strong ones, which often means a wrong key or an ambiguous question.
• Point-biserial: the correlation between getting the question right and the score on the rest of the test.
• Options: how many chose each option, and wrong options that attract the top group or that nobody chose.
• Reliability of the test: KR-20, or Cronbach’s alpha when partial marks are given.

The figures settle down with about 20 sheets or more; with a handful of sheets they are only a first impression.

Exports

• Results (CSV) opens in Excel, Google Sheets and LibreOffice: one row per sheet with roll number, name (from the class list), version, score, percent, right, wrong, blank and double marks, answers left to check, and every answer. Students on the class list without a sheet are listed too.
• Copy table puts the same table on the clipboard, ready to paste into a spreadsheet.
• Excel workbook: the results, the item analysis and a summary (mean, median, standard deviation, highest, lowest, reliability) on separate sheets.
• Item analysis (CSV): one row per question and version.

Results stay in this browser tab only — download them before you close it.

Limitations

• Only MySmartCoPilot’s printed sheets can be read: the scanner looks for its own black squares and bubbles.
• Use a dark pencil or a pen and fill the bubbles: ticks and crosses are read as light marks and sent to “To check”.
• A torn corner square, a fold through the bubbles or a very blurred photo stops a sheet from being read; take the photo again, or scan the sheet on a flatbed scanner.
• Old iPhone photos in HEIC format open only in Safari; other browsers need JPEG.
• Results are kept in the browser tab only, up to 300 sheets at a time: export them, then press Reset for the next batch.

Privacy

Photos, PDFs and camera pictures are read on your device, in a background worker of this page, and are never uploaded; the camera is used only while you scan. The class list and the results stay in this tab until you close it or press Reset. Only the answer keys and marking settings are remembered in this browser, to save typing next time.