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Qr codes

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It is a recent development in the field of Computer science, used to encode information within an abstract picture.Even though it provides same level of security as the bar codes, it ensures encoding of more amount of data as compared to the traditional ways of encoding.

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Qr codes

  1. 1. QR CODES Presented byEllina Priyadarshini
  2. 2. WHAT IS A QR CODE ? QR code: Quick Response code • Is a 2-D bar code • Used to encode information(URLs, automated SmS, text data) in two dimensional space.
  3. 3. HISTORY Created by a Japanese company- Toyota subsidiary Denso-wave in 1994. Used to track parts during vehicle manufacture
  4. 4. BARCODES V/S QR CODES  Stores data in two dimensions unlike the 1-D barcodes.  High storage capacity in less space.  Can be scanned by any smart phone with the app installed.
  5. 5. QR CODES IN EVERYDAY LIFE
  6. 6. INSIDE QR CODES      Finder Patterns: Finds if the given code is a QR Code Timing Pattern: Tracks the timing of the incoming code Separators: Separates data from the patterns Alignment Pattern: Tells about initiation & Separation of data. Dark Module: A black module placed beside the bottom left finder pattern.
  7. 7. QR CODE GENERATION DATA ANALYSIS  DATA ENCODING  ERROR CORRECTING  STRUCTURE FINAL MESSAGE  DATA MASKING  FORMAT INFORMATION STRING 
  8. 8. DATA ANALYSIS MODES SUPPORTED BY QR CODES: NUMERIC: for decimal digits from 0-9 • ALPHA-NUMERIC: digits from 0-9,upper-case • alphabets & symbols($,%,*,+,-,/,space) • BYTE: strings in form of hexadecimal bytes
  9. 9. DATA ENCODING:  STEP 1: Select error correction level.  STEP 2: Determine the smallest version for the data.  STEP 3: Add the mode indicator  STEP 4: Add the character count indicator  STEP 5: Encode using the selected mode  STEP 6: Breaking up to form code-words
  10. 10. ERROR CORRECTION CODING  Allows the QR code readers to detect & correct the errors in the code.  Reed-Solomon error-correcting algorithm is used. • Encoding symbols are derived from the coefficients of a polynomial constructed by multiplying p(x) with a generator polynomial.
  11. 11. STRUCTURE FINAL MESSAGE  If code-word is small, it is left as such.  Larger QR codes are broken up into blocks of either 15 or 16 data codewords each.
  12. 12. MODULE PLACEMENT IN MATRIX  The final string is placed in the QR code matrix along with the function patterns (discussed earlier). Fig. 1 Fig. 2 Fig. 3 Fig. 4
  13. 13. CONTINUED.. Fig. 4 Fig. 5 Fig. 6
  14. 14. DATA MASKING  “MASKING” means, changing the color of a module.  QR codes define 7 masking patterns.  For ex: in mask pattern #1, every even numbered row in the matrix is masked
  15. 15. FORMAT INFORMATION STRING  Includes the error correction level & the masking pattern currently in use.  (7x4) i.e. 28 format information strings exist.  Format string table gives the list of 28 format information strings.
  16. 16. HOW TO USE QR CODES?  Use a smart phone installed with a QR scanner app.  Open the app & place it in front of the QR code.  Get the result!!
  17. 17.  EXAMPLE:- ENCODED DATA HELLO WORLD DATA WORD 00100000 01011011 00001011 01111000 11010001 01110010 11011100 01001101 01000011 01000000 11101100 00010001 11101100
  18. 18. ERROR CORRECTION CODE 196 35 39 119 235 215 231 226 93 23 STRUCTURE FINAL MESSAGE 0100001111110110101101100100011 0010101011111011011100110111101110100011 0010000101111011101110110100001100000011101 110111010101100101011101110110001100101100001 000100110100001100000011100000110010101011111 0011101101101010101101010100111010101…….
  19. 19. QR CODE GENERATED
  20. 20. QUERIES

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