Using PHP to Access the Camera and Perform Face Detection with OpenCV

Camera devices are ubiquitous, and this guide shows how to perform object detection, specifically face detection, using PHP.

1. Install related libraries

To use PHP for object detection, install OpenCV and the php-facedetect library with the following commands:

sudo apt-get install python-opencv
sudo apt-get install unzip
wget https://github.com/nenadmarkus/pico
cd pico
unzip master.zip
cd /path/to/php-facedetect-master

2. Write PHP code

The following PHP script captures an image from the webcam, crops it, runs the pico face detection tool, parses the results, draws rectangles around detected faces, and outputs the image:

$x, 'y' => $y, 'width' => $size, 'height' => $size]);

// Save cropped image
imagejpeg($croppedImage, 'cropped.jpg');

// Call pico face detection
exec('pico/picornt cropped.jpg face.txt');

// Parse detection results
$faceTxt = file_get_contents('face.txt');
$faceTxt = explode("
", $faceTxt);
$faceCount = count($faceTxt);

// Draw rectangles on original image
for ($i = 0; $i < $faceCount - 1; $i++) {
    $faceData = explode(" ", $faceTxt[$i]);

    $x = $faceData[0] * $scale;
    $y = $faceData[1] * $scale;
    $width = $faceData[2] * $scale;
    $height = $faceData[3] * $scale;

    imagerectangle($image, $x, $y, $x + $width, $y + $height, imagecolorallocate($image, 0, 255, 0));
}

// Output image
header("Content-Type: image/jpeg");
imagejpeg($image);

// Clean up temporary files
unlink('image.jpg');
unlink('cropped.jpg');
unlink('face.txt');
?>

3. Run the code

Save the script as detection.php and execute it with php detection.php . If successful, the webcam image will be displayed with green boxes around detected faces.

Summary

Using PHP to access a camera for object detection demonstrates how OpenCV and php-facedetect can be combined to perform face detection, and the example can be adapted for other objects.

Note that this sample code is for demonstration only; production use may require more robust logic and algorithms.