Rectangular Micro QR Code

Rectangular Micro QR Code (“rMQR”) is a draft ISO standard currently being undertaken by JTC 1/SC 31/WG 1 that seems likely to become ISO/IEC 23941. It extends Micro QR Code ("μQR"), currently exclusively in the domain of square symbols, with a new fixed set of rectangular symbol sizes. These new sizes are ideal for marking curved surfaces such as test tubes as well as for application by a limited-height marking technology such as a continuous inkjet printer.

Recently Terry Burton Consulting implemented an encoder (i.e. a barcode generator) for the most recent version of the rMQR draft. The project was to extend Barcode Writer in Pure PostScript’s existing encoder for QR Code and μQR to support the new rectangular formats.

The good news is that from an implementer’s perspective the standard is in great shape. There were no significant errata discovered during the implementation and the information provided in the specification is complete and straightforward for anyone familiar with QR Code internals to understand and follow.

More importantly, the designers have done a really good job that we could characterise as “understand, embrace and extend”. They have made judicious choices regarding encoding considerations that ensure that the discrete symbol generation procedures of any existing, well-constructed QR/μQR implementation will require little, if any, amendment.

In particular, the new symbology introduces:

• New tables of constants: Symbol metrics, error correction block sizes, mode identifiers, character count and terminator lengths, fixed-pattern positions, ...
• A new set of finder, corner and alignment patterns, so implementations will need to rework the construction of the fixed patterns in the bitmap.
• And of course you need to undertake that task of splitting a single variable that represents the square symbol’s side length into separate row and column lengths that represent the dimensions of the rectangular bitmap.

But otherwise much unnecessary work is avoided:

• The encoding of the message into a bitstream and subsequent Reed Solomon encoding of blocks of codewords is the same, albeit with the revised constants.
• There is a single mask pattern for rMQR, that happens to already exist in the set of available mask patterns for μQR. This means of course that there is no expensive mask evaluation process required to select an optimal symbol candidate.
• The “drunken walk” module placement algorithm is identical to that of QR and μQR.
• The derivation of the format information modules follows essentially the same scheme as μQR.

All things considered, from first receiving a copy of the draft standard to committing the code changes to the existing QR Code encoder was a total of no more than two working days of effort.

Implementers with existing QR/μQR encoders should therefore be able to bring a feature-complete, correct rMQR encoder to market with only a trivial amount of time and effort once ISO/IEC 23941 is finalised.

That’s a really good testament to a job well done by the designers of rMQR.

If you would like any additional information concerning this upcoming symbology, its applicability to your application, or would like assistance with developing an encoder for the current rMQR draft standard, then Terry Burton Consulting is able to assist.