Matcha Design Blog

I've recently talked a lot about QR Codes, now I'd like to present a comparison to another "2D Barcode" technology - Microsoft Tag. Microsoft Tags and QR Codes are similar in many ways. They can be used for basically the same things - link to a web page, watch a video, download an app, start a phone call, get contact details - the primary difference is where this information comes from. With a QR Code, the information is stored in the code itself, but a Microsoft Tag only stores a database reference. The scanner app contacts Microsoft servers for the information stored in the relevant database entry. Read More...

We've covered almost everything we need to create QR Codes. The next thing we need is version information blocks. The version information blocks simply tell the reader what version the symbol is, and therefore how many modules wide and tall it is. Table 11 shows the top-right version of each version information block. Review Part 2 to see the positioning; in particular, remember to mirror these along the NW-SE axis to place them in the lower-left position. Read More...

Now that we've got the data and error correction sorted out, we're almost ready to place it in the symbol. As seen in Part 2, the data and error correction modules basically go everywhere that isn't taken up by something else. The reason we're not quite ready to place it is that we haven't established the locations of the alignment patterns. Read More...

I had planned on holding off the error correction until later, but it really fits better right here. Before error correction is done, the data that we've generated must be broken down into "code words", which are just 8-bit bytes. All we have to do is take our "bit stream" from the last tutorial, and break it into 8-bit sections. Each one is represented by a number in the range 0 to 255. Read More...

Now we'll cover how the data is encoded. There are several steps involved. First, the encoding method is chosen, then the raw data is converted to binary based on the encoding method, then the error correction algorithm is applied, and then the data is placed in the symbol. Finally a mask is selected and applied. For now I'll cover the encoding methods, and conversion to binary, and save the rest for later. Read More...

The next important thing we'll look at is the structure of a QR code. The below diagram shows names of the different sections of a QR symbol. Then I'll go over each one in more detail. Keep in mind that below if I mention one copy of something being the original and another a duplicate, it's just for the convenience of thinking about it that way - since the data is the same, it makes no difference which is placed first. Below I indicate what information is stored in the different sections, but I don't get into detail on how that information is encoded. I'll explain that in later weeks, and add in links as I complete the different sections. Read More...

Recently I undertook a task to develop a QR Code generator. I was surprised to find how difficult it was to find complete information on the QR Code specification. Most of what I found only explained part of the puzzle. So my new endeavor is to completely explain the spec. I want a skilled developer to be able to create a QR Code generator just by reading these tutorials. So I'll spend the next few weeks covering everything there is to know about QR Code generation. Read More...