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.

1. QR CODES
Presented byEllina Priyadarshini

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. HISTORY
Created
by a Japanese
company- Toyota subsidiary
Denso-wave in 1994.
Used to track parts during vehicle
manufacture

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. QR CODES IN EVERYDAY LIFE

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. QR CODE GENERATION
DATA ANALYSIS
 DATA ENCODING
 ERROR CORRECTING
 STRUCTURE FINAL MESSAGE
 DATA MASKING
 FORMAT INFORMATION STRING


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. 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. 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. 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. 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. CONTINUED..
Fig. 4
Fig. 5
Fig. 6

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. 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. 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. 
EXAMPLE:-
ENCODED
DATA
HELLO
WORLD
DATA
WORD
00100000 01011011 00001011
01111000 11010001 01110010
11011100 01001101
01000011 01000000 11101100
00010001 11101100

18. ERROR
CORRECTION
CODE
196 35 39 119 235
215 231 226 93 23
STRUCTURE
FINAL
MESSAGE
0100001111110110101101100100011
0010101011111011011100110111101110100011
0010000101111011101110110100001100000011101
110111010101100101011101110110001100101100001
000100110100001100000011100000110010101011111
0011101101101010101101010100111010101…….

19. QR CODE GENERATED

20. QUERIES