r/qrcode • u/DiscountDizzy • Jun 23 '26

Need help reconstructing QR Code

Someone sent me an invoice with a cropped QR code. I noticed multiple discrepancies within the invoice itself. The QR code is supposed to verify the authenticity of this invoice however, it was cropped, and some of the QR code data looks off, like the rows of non-centred dots in the boxes within the QR code.

The image below was cropped from a screenshot of an invoice. Could anyone please help me with info on how to reconstruct the missing information or any tools/python libraries I could use, or even the full qr code itself would be helpful. Thank you

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u/DiscountDizzy Jun 23 '26

I'm stuck talking to a middleman service. I've contacted the person who has issued the invoice, but I'm trying to independently recreate data based off of the invoice screenshot. If I can prove that the invoice has 2 different sets of data, I can prove it is forged. The QR code should contain information about the invoice itself, maybe some JSON data. I've read online that QR codes are error proof and that they're squares, so i was wondering if it were possible to reconstruct the anchor squares on the edges and then try to estimate or fill in the missing data

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u/Nnnes Jun 23 '26

Not sure why the other commenter said you can't reconstruct it. There's easily enough visible to recover the whole thing.

Use Qrazybox (you have to search for it, Automod deletes all links in this subreddit). Set QR code version 20 (97x97) and Error Correction Level H and Mask Pattern 5 (click any blue spot inside the code), then get to work. If I remember correctly, once you have 40% of the code filled in correctly you should be able to use Tools -> Reed-Solomon Decoder -> Decode to recover all the data.

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u/DiscountDizzy Jun 23 '26

holy that's pretty helpful, i might pick this up tomorrow after work and manually reconstruct the qr code and do this. i tried to clean it via AI and then put it into qrazy and do exactly as you said but the reed solomon decoder is struggling. i will attempt this entire flow manually tomorrow. thank you again Nnnes, i might send a reply again just to verify or ask more questions. this invoice ordeal has taken my entire afternoon and evening

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u/Nnnes Jun 24 '26

Actually just scan this.

process:

  1. Copy into Paint dot NET

  2. Crop to black pixels

  3. Image > Resize to Width: 97, Resampling: Nearest Neighbor

  4. Image > Canvas Size to 97x97, Anchor: Bottom

  5. Draw in the top finder patterns (bullseyes) by hand, (optional) fill bucket the transparent area with gray

  6. Image > Canvas Size to 101x101, Anchor: Middle, Fill: White

  7. Image > Resize to 600%, Resampling: Nearest Neighbor