ocv_qr_detect {opencv} | R Documentation |
Detect and Decode a QR code
Description
Detect and decode a QR code from an image or camera. By default it returns
the text value from the QR code if detected, or NULL if no QR was found. If
draw = TRUE
then it returns an annotated image with the position and
value of the QR drawn into the image, and qr text value as an attribute.
The qr_scanner
function opens the camera device (if available on your
computer) and repeats ocv_qr_detect until it a QR is detected.
Usage
ocv_qr_detect(image, draw = FALSE, decoder = c("wechat", "quirc"))
qr_scanner(draw = FALSE, decoder = c("wechat", "quirc"))
Arguments
image |
an ocv image object created from e.g. |
draw |
if TRUE, the function returns an annotated image showing the position and value of the QR code. |
decoder |
which decoder implementation to use, see details. |
Details
OpenCV has two separate QR decoders. The 'wechat' decoder was added in libopencv 4.5.2 and generally has better performance and fault-tolerance. The old 'quirc' decoder is available on some older versions of libopencv as a plug-in, but many Linux distros did not include it. If you get an error Library QUIRC is not linked. No decoding is performed. this sadly means your Linux distribution is too old and does not support QR decoding.
Value
if a QR code is detected, this returns either the text value of the QR,
or if draw
it returns the annotated image, with the value as an attribute.
Returns NULL if no QR was found in the image.
Examples
png("test.png")
plot(qrcode::qr_code("This is a test"))
dev.off()
ocv_qr_detect(ocv_read('test.png'))
unlink("test.png")