Hello, may I ask if the QR code with lighter color can not be recognized? (请问是不能识别颜色较浅的二维码吗?)

[fivefog]

The first two light-colored codes cannot be recognized. Is there a solution? (前两个颜色浅的码识别不了，有办法解决吗？)

[fengdh]

With ZBar.wasm(https://github.com/undecaf/zbar-wasm, https://github.com/samsam2310/zbar.wasm), I create an online live sample which outperforming jsQR with ability to detect multiple codes in one frame supporting multiple code types:
https://output.jsbin.com/nidonin

Open the link above and point to your colorful QR codes :-)

Here is also a sample based on jsQR for comparision:
https://output.jsbin.com/zevavin

[fengdh]

You can apply darken filter to your original image data, try both orginal and altered one with jsQR.

[ReginaLiang]

We can even make it pure black and white by using the following calculations:

black = 0 - 382
white = 383 - 765

I used follows code, these qr code can be decode.

for (i = 0; i < imgData.data.length; i += 4) {
    let count = imgData.data[i] + imgData.data[i + 1] + imgData.data[i + 2];
    let colour = 0;
    if (count > 383) colour = 255;

    imgData.data[i] = colour;
    imgData.data[i + 1] = colour;
    imgData.data[i + 2] = colour;
    imgData.data[i + 3] = 255;
}

Thanks.