What is a QR code?
A QR code, short for Quick Response code, is a type of barcode that can be read easily by a digital device and stores information such as text, URLs, contact information, etc. QR codes are commonly square shaped with a white background, black modules arranged in a square grid on the white background, and finder patterns located at the three corners of the symbol to help reading software locate and decode the QR code.
QR codes were initially used for tracking vehicle parts in manufacturing but have gained popularity in consumer advertising and packaging in recent years. When scanned by a smartphone, the black and white pixel QR code image is converted to binary code, analyzed to detect version information, format information, and error correction levels, and finally converted to meaningful data through Reed-Solomon error correction and data masking. This quick digital conversion from QR image to usable data is how the QR code got its name ‘Quick Response’.
Why would a QR code need fixing?
There are several reasons why a QR code may not work properly and need fixing:
– The QR code is damaged or obscured. Common damage includes rips, stains, creases in packaging material, or abrasion that makes it difficult for the QR reading software to detect and sample the QR modules. Obscuration such as being covered by other packaging or labels, being wrapped around a curved surface, reflective glare, or low lighting conditions can also lead to reading failures.
– The QR code size is too small for scanners to properly detect and read it. There are different recommended minimum sizes based on the barcode scanner technology, but QR codes under 0.5 inch or 1 centimeter square tend to have readability issues.
– Low quality generation of the QR code resulting in uneven cell sizes, low resolution, or lack of finder/timing patterns. Most free online QR generators limit file size and QR code pixel dimensions resulting in poor quality codes.
– Invalid or corrupt data encoded in the QR code. Errors in the input URL, text fields, contact data, etc. will lead to data read failures.
– Outdated QR code formats and standards. As technology evolves and new QR code versions and error correction levels are introduced, older QR codes can become obsolete. Most modern QR scanners maintain backwards compatibility, but there are exceptions.
How can I fix a corrupted or damaged QR code?
Here are some ways to try and fix a QR code that is not scanning or decoding properly:
Repair damage
For damaged QR codes on packaging, carefully repair tears with clear packing tape, touch up any light stains with marker, and flatten out any creases and wrinkles. The key is to make the QR code visually readable by eliminating any interference or obstructions to the QR modules and finder patterns.
Increase size
Try resizing the QR code to at least 1 inch or 2.5 cm square. There are many free QR code generator sites online that allow creating a new larger version of the same QR code. Make sure to disable any logo graphics within the code when increasing the size to maximize data reading area.
Boost contrast
For QR codes printed on reflective, colored, or dark surfaces, try boosting the contrast between the light and dark modules. Carefully apply white colored markers to lighten the modules, or apply black marker to any white space around the code to improve the distinction.
Minimize glare
QR codes under glass, plastic, or glossy material can create glare and reflections making it hard for the scanner to read the code. Try holding the code at different angles to minimize glare and reflections or add a matte overlay or cover to diffuse light.
Add lighting
Improving lighting on dim or poor quality QR codes can help with readability. Shine an LED flashlight directly on the code during scanning or position the code under a bright desk lamp. Avoid heavily angled side lighting that can create glare.
Regenerate the code
If you have the original input data (text, URL, etc) that created the QR code, regenerate a brand new high resolution and properly formatted QR code. Many free QR generator sites provide options to boost image resolution and error correction levels.
Try alternate QR readers
Some QR reading apps and scanners work better than others in suboptimal conditions. If one QR scanner fails, try alternate apps and tools. Some phones allow accessing the camera directly for QR reading without downloading a dedicated app.
Best practices for creating high quality QR codes
Follow these tips when generating QR codes to minimize readability issues:
Increase size
As mentioned above, QR code size has a big impact on scanning success rates. The bigger the code, the easier it is to read at high speeds and at wider angles. For consumer advertising and packaging, aim for 1-2 inch minimum QR code size.
Choose optimal colors
Stick with black modules on a white background. Other color combinations lead to data retention issues when scanned. Only use colors sparingly for logos or branding graphics within the quiet zone area, not overlapping the modules themselves.
Increase resolution
Higher resolution means clearer definition of the tiny QR modules. Choose at least 300×300 pixels for a 1-inch sized QR code. Higher resolutions provide even better clarity and scanning performance.
Select appropriate error correction
Error correction data allows the QR code to still be read even if part of the code is damaged or obscured. A 30% level enables recovery from about 15% code damage. Choose higher error correction for dirty or riskier environments.
Leave quiet zone spacing
The blank space or quiet zone around the outer edges of the QR code makes detection more consistent. Leave at least 4 module widths of blank margin all around the QR code symbol.
Get the input data right
Double check that any input text, URLs, contact data fields are entered correctly before generating the code. Accurate input data ensures a valid QR code that provides the expected results when scanned.
Other QR code troubleshooting tips
Here are some other additional pointers for tackling QR code readability issues:
Try scanning at different angles
Position the QR code square to the scanner camera and slowly tilt it at different angles. Certain perspectives may minimize glare or reflections.
Clean scanner lens
Dust, fingerprints, and dirt on the camera lens of a smartphone or QR scanner can interfere with focusing and code reading accuracy. Gently wipe the lens with a clean microfiber cloth.
Update the app/scanner software
Older QR reading software may not support newer QR code formats and standards. Check for any app updates and keep the QR scanner software current.
Enable auto-focus
Most modern QR scanners automatically focus on the barcode, but some lower cost models require manually enabling an auto-focus function. Refer to scanner documentation.
Add code outlines
For QR codes printed on backgrounds with similar contrast or color, consider adding a bold outer border around the code to improve finding and focusing.
Conclusion
The main ways to fix a problematic QR code are repairing any damage, increasing size and resolution, adjusting colors and contrast for improved readability, regenerating the code if corrupted, trying alternate QR readers, and tweaking positioning and lighting during scanning. When creating new QR codes, follow best practices on sizing, image quality, error correction, quiet zone margins, and input data validation to maximize scanability and decoding accuracy across the broadest range of conditions. With a bit of troubleshooting effort, even damaged and neglected QR codes can typically be repaired and restored to working order.