Метод 1: использование file_put_contents()

$data = 'base64-encoded-image-data';
$file = 'path/to/save/image.jpg';
if (file_put_contents($file, base64_decode($data))) {
    echo 'Image saved successfully.';
} else {
    echo 'Failed to save image.';
}

Метод 2: использование fopen() и fwrite()

$data = 'base64-encoded-image-data';
$file = 'path/to/save/image.jpg';
if ($handle = fopen($file, 'wb')) {
    if (fwrite($handle, base64_decode($data)) !== false) {
        echo 'Image saved successfully.';
    } else {
        echo 'Failed to save image.';
    }
    fclose($handle);
} else {
    echo 'Failed to open file.';
}

Метод 3: использование imagecreatefromstring() и imagejpeg()

$data = 'base64-encoded-image-data';
$file = 'path/to/save/image.jpg';
$image = imagecreatefromstring(base64_decode($data));
if ($image !== false) {
    if (imagejpeg($image, $file)) {
        echo 'Image saved successfully.';
    } else {
        echo 'Failed to save image.';
    }
    imagedestroy($image);
} else {
    echo 'Invalid image data.';
}