Invert pixels - zxing

Question

I\'m using a zxing library in my iOS project. It\'s a library for reading and creating QR Codes.

From my researching and browsing around the web the process of decod

Answer 1

You don't want to print the values as characters because they aren't ASCII. Print them as unsigneds:

printf(" %u", ...);

You can simplify the loop to simply

result[i] = static_cast<unsigned char>(255 - result[i]);

The other conversions are normal integral promotion.

And you should note that ZXing uses some asymmetric heuristics when identifying codes. If you don't have a guard region surrounding the code that is, in this case, black (since the guard region is supposed to be white), it may fail to identify the code.