QR code / bar code scanner? - Operating System

Hello,

If you are looking for more details, kindly visit Qr Scanner Module.

Most Android smartphones rely on the Photo app to scan (and convert) QR codes / bar codes.
But AFAIK, Open Camera has no QR code / bar code module.

Does Iodé include QR code / bar code scanning ability in another App, or should I download an app ?

F-droid has “QR & Barcode Scanner”, “Obsqr”, “QR Scanner (PFA)”, “QRCode & Barcode scanner” and “SecScanQR” among others.
Any opinion about them ?

Thanks !

Cobus.

What are QR Codes? 

Masahiro Hara developed the quick response system symbol, better known as the QR code, to speed up code reading on car parts. He achieved his goal and much more; the technology became an ISO standard thanks to the multiple advantages it offered over traditional bar codes, including:

• Up to 10x faster decode times
• Greater data storage capacity
• Flexible sizes
• Readability in any orientation
• Readability with up to 30% of the code damaged

These benefits depend on the quality of the QR code, though. Companies producing QR codes for internal or public use need to make sure they’re easily decoded, and the best way to do that is by using a barcode verifier. Barcode verifiers analyze QR codes by testing several parameters to determine an overall quality grade.

Before diving into the grading process, let’s review the parts of a QR code. 

Beginners Guide to Barcode Verification

Understanding the Structure of QR Codes

Quiet Zone: Space around the edge of the code that helps separate the code from nearby design elements or markings. The minimum size is 1 module – the size of the smallest squares in the code – in the ISO 16480 standard for QR codes or 4 modules in the ISO 18004 standard for QR codes meant to be read on mobile devices.

Finder Pattern: Three identical nested sets of black and white squares that make it faster and easier for scanners to determine orientation and read the code.

Alignment Pattern: Smaller black and white nested squares that ensure the code can be read even if the code is skewed or on a curved surface. They tell the reader software where to place the grid. 

If you want to learn more, please visit our website Handheld Android Scanner.

• The larger the code, the more alignment patterns it will need. 
• QR codes more than 45 modules require multiple alignment patterns. 

Timing Pattern: An L-shaped line that runs between the three finder pattern squares helps readers determine how large the modules are and where the data is located. 

Format Information: Specific areas of the code that specify error tolerance and a data masking pattern. 

Version Information: Specific areas of the code that identify which of the 40 versions of QR codes is being used, and identifies the data mask, error correction levels, and link values used in the symbol. As with extra alignment patterns, this information is only listed in symbols bigger than 45 x 45 modules. 

Data and Correction Keys: The bulk of the code, using light and dark modules for data and error correction. 

• Error correction allows up to 30% of the code to be damaged but still be decoded. 

The QR Code Grading Process

QR codes are graded based on the steps of the decoding process. The details are set out in the ISO 15415 standard for label-printed codes, and ISO 29158 for codes directly marked onto parts (DPM).  

Symbol reading software begins decoding by locating the three large finder patterns in the corners of a code. Once those patterns are found, the clock track and alignment patterns establish a character grid. Each module's color is measured at the intersection of the grid lines, which fall near the center of the modules, and that color is compared to the color the module is supposed to be.

Circular Sampling for Color Measurement

The color of a module is measured within a circular sample called the aperture, centered on the intersection of the grid lines. Since the image will often have varying shades of gray within the aperture, readers use the average color within that area to evaluate the module. 

Determining Dark or Light Modules

The average values for all the modules in a code are plotted on a graphic called a histogram. The gray midway between the darkest and lightest levels found in the code is then set as the global threshold. Each module is interpreted as light or dark based on whether it’s lighter or darker than the global threshold. This allows readers to adapt to varying lighting conditions and printed backgrounds. 

Grading QR Code Modules

Once a module is determined to be dark or light, the actual color level is evaluated to see how close it is to the global threshold. More distance from the global threshold is better: light modules should be among the brightest spots in the images and darks should close to the darkest.

To reflect this, modules get higher grades based on their distance from the middle of the histogram, and lower grades as they get closer to the global threshold.

The overall grade of a QR code depends on the grades of all its component parts: finder patterns, clock tracks, version information blocks, format information blocks, alignment patterns, and regular data modules.

The grading rules for each module are different depending on how much they affect the readability of the QR code. 

Finder Pattern Grading Parameters

After cell colors have been determined, the next phase in the decode process is to identify the finder pattern: 

Grade assingment for finder patterns: 

Want more information on Decipher Barcode? Feel free to contact us.

• 0 incorrect modules-A
• 1 incorrect module-B
• 2 incorrect modules-C
• 3 incorrect modules-D
• 4 or more incorrect modules-F