二维码基础知识
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Error Correction Capability (ECC)
Increase the effective density of the encoding: more data in a smaller space Portable database (rather than just a database key): encode complete data files in an optically readable symbol and so … … extend the potential market for AUTO-ID
Additional characters to provide error detection/correction
Special characters to sign
number of rows row number of the individual row
Readable by raster laser scanners, linear CCD devices or matrix cameras.
Vertically Redundancy: same information repeated in Y-axis tolerates printing dropout Made up of one series of bars and spaces of different width (not only binary modulation) Machine readable “licence plate”: key into a data base containing detailed information BUT ...
Datalogic Automation
Linear (1D) Codes symbologies
Information only on X-axis (one single row)
Low capacity, typically 15 to 50 character carrying capability, depending upon symbology and the symbol form
USS-TSS Unattended Scanning Systems Technical Support & Services Barcodes & 2D Codes Place - DD/MM/YYYY - Session XX
2D Codes Fundamentals
Datalogic Automation
each row is a series of one-dimensional barcodes each row (or slice row) is designed to be scanned in a linear manner the message continues from row to row
… this is not “on the spot and on the fly”
Datalogic Automation
2D Codes Symbologies
Two-dimensional code: information along the height (X-axis) as well as the length (Y-axis) of the symbol No vertically redundancy 2D Codes tolerates printing dropouts because of
Stacked symbologies evolved as 1D codes stacked in horizontal layers to create the Multi-row symbologies
Rectangular block made up of thin barcodes vertically stacked on top of each other Many of the characteristics of the linear barcode:
PDF417 structure
Standard PDF417 code has the following structure:
R1 R2 R3 … Rn C1 C2
… …
R1 R2 R3
…
… Rn
…
Cm
Where: Rx: Row indicator/Left and Right Cx: Check Character/Codeword
There are two types of 2D codes in current use:
Multi-row (or Stacked) Codes Matrix Codes
Datalogic Automation
Multi-row (Stacked) Symbologies (1/2)
Datalogic Automation
Module’s Contents
2D Codes Introduction Stacked Symbologies
PDF417 and Micro PDF417
Matrix Symbologies
Data Matrix code QR Code Aztec Code Maxicode
Maximum data per symbol: Numeric: 2710 digits Alphanumeric: 1850 characters
Most popular applications: Government/Postal: identification cards, official documents Healthcare: specimen tracking, claims processing Logistic:package tracking, shipping list Manufacturing: process control, quality control, component control
Datalogic Automation
Micro PDF417
Micro PDF417:
Derived from and closely based on standard PDF417 Number of rows: 1-4 Number of columns: 4-44 A limited set of symbol sizes is available, together with a fixed level of error correction for each symbol Micro PDF417 is designed for applications with a need for improved area efficiency, but without the requirement for PDF417's maximum data capacity Maximum data per symbol: Numeric: 366 digits Alphanumeric: 250 characters
The most used stacked codes are:
PDF417 family
Code 49
Code 16K Codablock A & F ...
Datalogic Automation
PDF417
1992, Symbol
PDF: Portable Data File Number of rows: 3-90 Number of columns: 1-30 Row width: start/stop pattern, 3-32 characters, quite zone Seven user selectable Error Correction Levels Variations: Macro PDF417, Micro PDF417, Truncated PDF417
Datalogic Automation
Multi-row (Stacked) Symbologies (2/2)
Maximum Data Capacity:
up to 2710 digits + “Structure Append” capability for concatenation of multiple symbols
GS1 DataBar Symbologies Composite Symbologies Postal Codes
Australia Post
Sectors and Applications Glossary
Datalogic Automation
Why Do We Need 2D Symbols?
Start: PDF417 Start Pattern Stop: PDF417 Stop Pattern
Datalogic Automation
PDF417 Error Correction Capability
A significant amount of a Stacked or 2D symbol can be destroyed and still recover 100% of the information
Datalogic Automation
Matrix Symbologies (1/2)
Matrix symbologies offer higher data densities than Stacked codes in most cases Composition of cells in an array structured on a grid Help to localization of codes: “Finder Pattern” Cell characteristics: regular, polygonal shaped, uniform center to center distance, dark and light Binary encoding: dark and light cells stand for 0 and 1 Error detection and correction techniques to improve reading reliability and enable reading of partially damaged symbols Orientation-independent scanning Readable only by Imager devices like linear CCD cameras or vision systems.
We need -using less space- more information in time and at the point of decision:
“on the spot and on the fly”
2D labels on blood transfusion bag cross-checked against 2D symbols on patient’s wrist band. 100 character square inch Maxicode drives a package through a distribution network. Information encoded in a 2D symbol on a product available at a POS. PDF417 symbology inside of an automobile door frame. Data Matrix ECC200 printed on a computer chip: traceability and identification data.
Most popular applications:
Document handling applications Microsoft product key stickers Also used as part of the Composite symbologies
Datalogic Automation
Increase the effective density of the encoding: more data in a smaller space Portable database (rather than just a database key): encode complete data files in an optically readable symbol and so … … extend the potential market for AUTO-ID
Additional characters to provide error detection/correction
Special characters to sign
number of rows row number of the individual row
Readable by raster laser scanners, linear CCD devices or matrix cameras.
Vertically Redundancy: same information repeated in Y-axis tolerates printing dropout Made up of one series of bars and spaces of different width (not only binary modulation) Machine readable “licence plate”: key into a data base containing detailed information BUT ...
Datalogic Automation
Linear (1D) Codes symbologies
Information only on X-axis (one single row)
Low capacity, typically 15 to 50 character carrying capability, depending upon symbology and the symbol form
USS-TSS Unattended Scanning Systems Technical Support & Services Barcodes & 2D Codes Place - DD/MM/YYYY - Session XX
2D Codes Fundamentals
Datalogic Automation
each row is a series of one-dimensional barcodes each row (or slice row) is designed to be scanned in a linear manner the message continues from row to row
… this is not “on the spot and on the fly”
Datalogic Automation
2D Codes Symbologies
Two-dimensional code: information along the height (X-axis) as well as the length (Y-axis) of the symbol No vertically redundancy 2D Codes tolerates printing dropouts because of
Stacked symbologies evolved as 1D codes stacked in horizontal layers to create the Multi-row symbologies
Rectangular block made up of thin barcodes vertically stacked on top of each other Many of the characteristics of the linear barcode:
PDF417 structure
Standard PDF417 code has the following structure:
R1 R2 R3 … Rn C1 C2
… …
R1 R2 R3
…
… Rn
…
Cm
Where: Rx: Row indicator/Left and Right Cx: Check Character/Codeword
There are two types of 2D codes in current use:
Multi-row (or Stacked) Codes Matrix Codes
Datalogic Automation
Multi-row (Stacked) Symbologies (1/2)
Datalogic Automation
Module’s Contents
2D Codes Introduction Stacked Symbologies
PDF417 and Micro PDF417
Matrix Symbologies
Data Matrix code QR Code Aztec Code Maxicode
Maximum data per symbol: Numeric: 2710 digits Alphanumeric: 1850 characters
Most popular applications: Government/Postal: identification cards, official documents Healthcare: specimen tracking, claims processing Logistic:package tracking, shipping list Manufacturing: process control, quality control, component control
Datalogic Automation
Micro PDF417
Micro PDF417:
Derived from and closely based on standard PDF417 Number of rows: 1-4 Number of columns: 4-44 A limited set of symbol sizes is available, together with a fixed level of error correction for each symbol Micro PDF417 is designed for applications with a need for improved area efficiency, but without the requirement for PDF417's maximum data capacity Maximum data per symbol: Numeric: 366 digits Alphanumeric: 250 characters
The most used stacked codes are:
PDF417 family
Code 49
Code 16K Codablock A & F ...
Datalogic Automation
PDF417
1992, Symbol
PDF: Portable Data File Number of rows: 3-90 Number of columns: 1-30 Row width: start/stop pattern, 3-32 characters, quite zone Seven user selectable Error Correction Levels Variations: Macro PDF417, Micro PDF417, Truncated PDF417
Datalogic Automation
Multi-row (Stacked) Symbologies (2/2)
Maximum Data Capacity:
up to 2710 digits + “Structure Append” capability for concatenation of multiple symbols
GS1 DataBar Symbologies Composite Symbologies Postal Codes
Australia Post
Sectors and Applications Glossary
Datalogic Automation
Why Do We Need 2D Symbols?
Start: PDF417 Start Pattern Stop: PDF417 Stop Pattern
Datalogic Automation
PDF417 Error Correction Capability
A significant amount of a Stacked or 2D symbol can be destroyed and still recover 100% of the information
Datalogic Automation
Matrix Symbologies (1/2)
Matrix symbologies offer higher data densities than Stacked codes in most cases Composition of cells in an array structured on a grid Help to localization of codes: “Finder Pattern” Cell characteristics: regular, polygonal shaped, uniform center to center distance, dark and light Binary encoding: dark and light cells stand for 0 and 1 Error detection and correction techniques to improve reading reliability and enable reading of partially damaged symbols Orientation-independent scanning Readable only by Imager devices like linear CCD cameras or vision systems.
We need -using less space- more information in time and at the point of decision:
“on the spot and on the fly”
2D labels on blood transfusion bag cross-checked against 2D symbols on patient’s wrist band. 100 character square inch Maxicode drives a package through a distribution network. Information encoded in a 2D symbol on a product available at a POS. PDF417 symbology inside of an automobile door frame. Data Matrix ECC200 printed on a computer chip: traceability and identification data.
Most popular applications:
Document handling applications Microsoft product key stickers Also used as part of the Composite symbologies
Datalogic Automation