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.
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.
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.
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
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!!