QR Code Data Masking? Not finding any mention in decoders or generators.

[raccoon]

Hi guys,

I've been looking (for years) for any code generators or decoders that support or imply support for "Data Masking" as per the ISO/IEC specification. This is the application of any one of 8 "data mask patterns" to the finished QR code (one of 4 patterns for Micro QR codes), to give variety to the aesthetic appearance and functional contrast of a code, ie, to avoid large blobs that may interfere with timing and decoding.

I notice that the relatively new zxing.appspot.com doesn't support data masking, and I would be interested to know if the main zxing library even provides decode support.

Regards,

R

P.S. Since the words "data mask" don't appear anywhere in this group's archive of posts, I'll include the mask functions here for quick reference.

000 (i + j) mod 2 = 0
001 imod 2 = 0
010 jmod 3 = 0
011 (i + j) mod 3 = 0
100 ((i div 2) + (j div 3)) mod 2 = 0
101 (i j) mod 2 + (i j) mod 3 = 0
110 ((i j) mod 2 + (i j) mod 3) mod 2 = 0
111 ((i j) mod 3 + (i+j) mod 2) mod 2 = 0

Where i refers to the row position of the module in question and j to its column position, with (i, j) = (0, 0) for the top left module in the symbol.

-R

[Lachezar Dobrev]

  The Data Mask application in ZXing is automatic when encoding a QR Code. The library choose a best-fit one based on number of "penalty" metrics which lead to choosing the mask that will lead to the least deterioration artefacts in the result code.
  [1] com.google.zxing.qrcode.encoder.Encoder @ 57
  [2] com.google.zxing.qrcode.encoder.Encoder @ 229
  [3] com.google.zxing.qrcode.encoder.MaskUtil

-R

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[Sean Owen]

Masking is actually required and has always been implemented:

https://github.com/zxing/zxing/blob/master/core/src/main/java/com/google/zxing/qrcode/encoder/MaskUtil.java

Certainly, the online encoder does it.