QR code glossary · Design and printing
Logo in a QR code
Also called: QR code with logo, Branded QR code
Definition
A logo in a QR code is an image placed over part of the pattern, usually the center, which works because Reed–Solomon error correction can rebuild the modules the logo hides, provided the logo stays within the correction budget and clear of the finder patterns.
How it works
The QR code standard says nothing about logos. A logo works by spending part of the error correction budget on purpose: every codeword under the logo reads wrong, and Reed–Solomon decoding restores it, as it would for a stain.
That budget is counted in codewords, and each codeword is a block of 8 modules, so any codeword the logo touches counts as damaged, even if only one of its modules is covered. The logo also must not cover anything error correction does not repair: the finder patterns, the format information beside them and the timing patterns. In versions 7 to 13 a centered logo also hides an alignment pattern.
Why it matters
Rules of thumb that follow from this (none is a standard requirement):
- Use level H, which restores about 30% of codewords, the most headroom available.
- Think in area, not width. A logo a quarter of the code’s width covers about 6% of its area; a third of the width covers about 11%.
- Leave headroom. The budget also has to absorb wear, glare and print defects, so a logo should use well under 30%.
- Knock out the modules under the logo and give it a plain background, rather than laying a semi-transparent image over the pattern.
- Test each size and placement with several phones before printing.
Example
A 28-character short link at level H is version 4, 33 × 33 modules (1,089 in all). A centered logo a quarter of the width covers about 8 × 8 = 64 modules, around 6% of the area, but it touches more codewords than 64 ÷ 8 = 8, because codewords along its edges are only partly covered.
In CirculateQR
The free generator places your logo in the center at up to 25% of the code’s width and switches to level H automatically. In the Studio app, logos are part of branded codes on Studio and higher plans, also at level H.
Related terms
- Error correction levelAn error correction level is the setting, L, M, Q or H, that decides how much redundant data a QR code carries; the four levels let a scanner restore roughly 7%, 15%, 25% and 30% of the code’s codewords when they are damaged, dirty or covered.
- Reed–Solomon error correctionReed–Solomon error correction is a family of error-correcting codes, published by Irving Reed and Gustave Solomon in 1960, that QR codes use to add calculated check codewords to their data so a scanner can find and repair codewords it misread.
- Finder patternA finder pattern is one of the three large concentric squares in the top-left, top-right and bottom-left corners of a QR code, which a scanner uses to detect the code, measure its size and angle, and work out which way up it is.
- Alignment patternAn alignment pattern is a small 5 × 5 module square, a dark ring around a light ring around a single dark module, placed at regular intervals inside QR codes of version 2 and above so a scanner can correct for tilt, perspective and curved surfaces.
- Contrast ratioContrast, for a QR code, is the difference in brightness between its dark and light modules; scanners need a large difference, with the dark modules darker than the light ones, and designers often check it with the WCAG contrast ratio, which runs from 1:1 (no difference) to 21:1 (black on white).
- AI QR code artAI QR code art is an image made with a generative AI model so that a working QR code is part of the picture, with the code’s dark and light modules formed by elements of the scene instead of plain squares.
Learn more
- Custom QR code design: Brand colors, shapes and your logo.
- QR code error correction levels explained: A worked example of logo size.
- Free QR code generator: Add a logo to a static code.
Sources
Last updated . Written by the CirculateQR team; technical facts follow the sources listed above. Example codes and sizes are computed with the open-source qrcode encoder that CirculateQR uses. Spotted something wrong? Email support@circulateqr.com. QR Code is a registered trademark of DENSO WAVE INCORPORATED.
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