why is mine QR code can not be read?

[ziming zhong]

Hi! I have 300 images with QR codes, and I use a wrap-up package (https://ch.mathworks.com/matlabcentral/fileexchange/29239-qr-code-encode-and-decode?focused=5170461&tab=function) from Zxing codes in MatLab to read these codes. But I found that 160 out of 300 codes can not be read, and I don't really understand why. My codes have a bit damages, but i guess it is not more than 30%. Some of the codes with quite a lot of damages can still be read and some with little damage can not be read. I don't really know why and how to improve it. Could somebody help me?

[Sean Owen]

The printed barcode looks a bit corrupted, like the modules aren't of equal width. It could be an artifact of the image too, like the blur on other images.

However, I think the real reason may be that they are "old" QR codes (not the 2005 spec). I am not sure, but the third one's border sure reminds me of how they look, which is subtly different. That format isn't supported by this library.

[ziming zhong]

On Tuesday, December 26, 2017 at 1:57:30 AM UTC+1, Sean Owen wrote:
> The printed barcode looks a bit corrupted, like the modules aren't of equal width. It could be an artifact of the image too, like the blur on other images.
>
>
> However, I think the real reason may be that they are "old" QR codes (not the 2005 spec). I am not sure, but the third one's border sure reminds me of how they look, which is subtly different. That format isn't supported by this library.

Thanks Sean for the reply! These codes are generated recently by using the Zxing library too. I use a package in Matlab (https://ch.mathworks.com/matlabcentral/fileexchange/49808-qr-code-generator-1-1-based-on-zxing).

It's also very strange for me that some codes that can be decoded by Zxing online decoder but not in MatLab when I used the wrap-up package. Here I attached a small picture to show. I don't understand why, as the library is the same, right?