Micro QR-codes are not detected

[acriba]

We are trying to use nano qr codes because we need to encode very little information and would like to minimize size. The codes are mostly detected but there are some qr codes that can't be decoded and I have no idea where the problem lies. It seems that somehow the position of the qr code is completely misdetected, which results in an error ERROR_CORRECTION. I have painted the detected bounding boxes above the samples. I include also a few succesful examples - I don't have an idea why the boundaries are not detected correctly in these cases. The qr-codes are generated with boofcv. Maybe somebody has a hint or something can be improved?

[lessthanoptimal]

Can you post the miss detections without any overlays? Also what software did you use to generate the micro QR.

Just looking at your annotation, the issue is that for some reason it has a boundary box that's the wrong size. This could be caused by a localization error in the small pattern in the top left. The boundary box being at the wrong location is an artifact of it trying all 4 possible orientations before giving up.

Are you thresholding the image first before processing? It might work better without thresholding. It uses information from the gray scale aliasing to fit a better shape to the marker.

• Peter

On Fri, Jun 9, 2023 at 1:48 AM acriba @.***> wrote:

We are trying to use nano qr codes because we need to encode very little information and would like to minimize size. The codes are mostly detected but there are some qr codes that can't be decoded and I have no idea where the problem lies. It seems that somehow the position of the qr code is completely misdetected, which results in an error ERROR_CORRECTION. I have painted the detected bounding boxes above the samples. I include also a few succesful examples - I don't have an idea why the boundaries are not detected correctly in these cases. The qr-codes are generated with boofcv. Maybe somebody has a hint or something can be improved? [image: success03] https://user-images.githubusercontent.com/14861362/244641994-10fb0385-baa8-4c9d-8d2e-011bc7415791.png [image: success02] https://user-images.githubusercontent.com/14861362/244642003-fef0060e-fe90-4b12-9fdd-d5965d0252dc.png [image: success01] https://user-images.githubusercontent.com/14861362/244642007-4a7b8711-0ebe-4226-9356-78089f16b4c3.png [image: error03] https://user-images.githubusercontent.com/14861362/244642011-25d47c41-195f-4a21-a5c7-3b21334d9676.png [image: error02] https://user-images.githubusercontent.com/14861362/244642019-65b35bc4-131c-4f1f-b2a5-e6910308dc85.png [image: error01] https://user-images.githubusercontent.com/14861362/244642022-288c51b3-10bb-4b01-905f-523e2e22128a.png

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[acriba]

Hello Peter, I appreciate your your help - thank you very much.

We are using BoofCV to create the Micro QR code (sorry for using the wrong name before). We are not using thresholding, we convert the original image with to a grayscale image.

I have attached the grayscale image gray that is used by the detector. We convert the original color image with ConvertBufferedImage.convertFromSingle(original, null, GrayU8.class);:

    var config = new ConfigMicroQrCode();
    MicroQrCodeDetector<GrayU8> detector = FactoryFiducial.microqr(config, GrayU8.class);
    detector.process(gray);

Christian

[lessthanoptimal]

Sorry for taking a bit to reply. The images you posted look a bit noisy. Can you paste the code you used to generate these markers? It's also possible that they are somehow in an illegal state. I hope to be able to dive into this soon.

[acriba]

Hello Peter,

here would be the code that we are using to generate the Codes:

public byte[] getMicroQrCode() {

    MicroQrCode qr = new MicroQrCodeEncoder()
            .setError(MicroQrCode.ErrorLevel.M)
            .addAutomatic(getData())
            .fixate();

    GrayU8 rendered = MicroQrCodeGenerator.renderImage(3, 2, qr);
    BufferedImage image = ConvertBufferedImage.convertTo(rendered, null);

    try(ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
        ImageIO.write(image, "png", baos);
        return baos.toByteArray();
    } catch (IOException e) {
        throw new RuntimeException(e);
    }

}

I don't think the codes could end up in an illegal state?

Christian