decode inverted QR code zxing

Question

I found that there is a variable, called "int[] stateCount", in FinderPatternFinder class helps checking for any possible finder pattern in a QR code. In order to detect/locate the Finder Patterns, I am thinking to make changes of this variable would be helpful. Any ideas on how to detect/decode a color inverted QR code in Java with ZXing?

score 2 · Answer 1 · edited May 23 '17 at 11:46

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I'm not a java programer but since I have managed to alter the zxing source to implement scanning inverted codes in my iOS project maybe my implementation will help you.

Invert pixels - zxing

edited May 23 '17 at 11:46

Community

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answered Feb 13 '12 at 18:14

Francis Bagan

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Thanks Francis! Have you put your alteration of the zxing source into an open source repo? – Uniphonic Feb 23 '17 at 17:22

score 0 · Answer 2 · answered Jan 25 '12 at 17:59

Not sure what you mean by color inverted. Do you mean swapping light and dark? In theory, you should be able to take an image, extract the luminance, and invert it, e.g., 255-pixel_luminance. Note that the quiet zone (surrounding white) needs to be inverted as well, i.e., surrounding black. And it's possible this won't work anyway. The zxing heuristics are not always symmetric. You can give it a shot but it may not work.

Note that zxing only extracts luminance. Two colors of very different hues but the same luminance are indistinguishable to the detectors/decoders.

In any case, mucking with stateCount is probably not going to help. At that point, the image is purely black and white, not even grayscale. You want to take any variations/distortions in your image into account ahead of this and leave this code untouched.

decode inverted QR code zxing

2 Answers2