Functional Barcode Decoder

A purely functional Scala application that processes raw image files and decodes standard 13-digit barcodes.

This project implements a complete image processing pipeline from scratch: - reading raw binary data - applying luminosity conversions - thresholding - using Run-Length Encoding (RLE) to parse and validate barcode digits

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🚀 Key Features

Custom Image Parsing (Parser.scala)

• Parses raw binary .ppm (P6) files
• Builds internal RGB data structures
• No external graphics libraries used

Image Processing Pipeline (Convertor.scala)

• Grayscale Conversion
  • Converts RGB .ppm → grayscale .pgm
  • Uses standard luminosity weights
• Binarization
  • Converts grayscale → black & white (.pbm)
  • Uses dynamic, quadrant-based thresholding
  • Handles uneven lighting conditions

Functional Decoding Engine (Decoder.scala)

• Extracts pixel rows

• Applies Run-Length Encoding (RLE) to detect bar widths

• Normalizes sequences using custom RatioInt

• Handles scaling and distortion

• Digit decoding:

  • Left side (Odd / Even parity)
  • Right side patterns

• Validation:

  • Uses standard EAN-13 checksum

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📁 Project Structure

• Types.scala
  Algebraic Data Types (ADTs):

  • pixels
  • bits
  • parities
  • image formats

• Parser.scala
  Byte-level parsing of .ppm headers and data

• Convertor.scala
  Image transformations:

  • RGB → Grayscale
  • Grayscale → B&W

• Decoder.scala
  Core decoding logic:

  • sequence chunking
  • parity matching
  • checksum validation

• Main.scala / MyBarcodes.scala
  Application entry points:

  • define input/output paths
  • orchestrate pipeline

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💻 Build and Run

This project uses sbt (Scala Build Tool).

Steps

1. Place .ppm images into:
   • MyBarcodesInput/
   • or InitialBarcodes/
2. Run:

sbt run

Output

• Generates processed .pbm images
• Prints decoded 13-digit barcodes in console

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🧠 Technical Highlights

Pure Functional Design

• No mutable state
• Composable transformations
• Clear separation of concerns

Robust Image Handling

• Works directly with raw binary formats
• No external dependencies

Resilient Decoding

• Handles noise and distortion
• Uses normalization (RatioInt)
• Validates results via checksum