Adding a watermark to your post images enhances brand recognition and protects your content from unauthorized use. In this tutorial, we'll create a script to automatically add watermarks when uploading images. We'll use PHP for this task.

Step 1: Setting Up the Environment

Before getting started, ensure you have:

• A PHP development environment set up.

• A folder to store uploaded images and a watermark image.

Watermark Image: This should be a transparent .png file.
 

Step 2: Write the Code

Here’s the code snippet for adding a watermark:
 

function CreatePost($request_values) {
    global $conn, $errors;

    // Sanitize input and retrieve user details
    $title = esc($request_values['title']);
    $featured_files = $_FILES['featured_images'];
    $watermarkImagePath = '../assets/post_images/watermarklarge.png';

    foreach ($featured_files['name'] as $key => $file_name) {
        $file_type = pathinfo($file_name, PATHINFO_EXTENSION);
        $target = "../assets/post_images/" . basename($file_name);

        if (move_uploaded_file($featured_files['tmp_name'][$key], $target)) {
            if (in_array($file_type, ['jpg', 'jpeg', 'png', 'gif', 'webp'])) {
                // Load image and watermark
                $watermarkImg = imagecreatefrompng($watermarkImagePath);
                switch ($file_type) {
                    case 'jpg':
                    case 'jpeg':
                        $im = imagecreatefromjpeg($target);
                        break;
                    case 'png':
                        $im = imagecreatefrompng($target);
                        break;
                    case 'gif':
                        $im = imagecreatefromgif($target);
                        break;
                    case 'webp':
                        $im = imagecreatefromwebp($target);
                        break;
                }

                // Position watermark and apply it
                $sx = imagesx($watermarkImg);
                $sy = imagesy($watermarkImg);
                imagecopy($im, $watermarkImg, imagesx($im) - $sx - 20, imagesy($im) - $sy - 20, 0, 0, $sx, $sy);

                // Save the watermarked image
                switch ($file_type) {
                    case 'jpg':
                    case 'jpeg':
                        imagejpeg($im, $target);
                        break;
                    case 'png':
                        imagepng($im, $target);
                        break;
                    case 'gif':
                        imagegif($im, $target);
                        break;
                    case 'webp':
                        imagewebp($im, $target);
                        break;
                }

                // Free memory
                imagedestroy($im);
            }
        }
    }
}

Step 3: How It Works

1. Upload Handling: The script iterates through each uploaded image.

2. Watermark Application:

   • Loads the uploaded image and the watermark image.

   • Places the watermark at the bottom-right corner of the uploaded image.

3. Output: The modified image is saved, replacing the original file.

Step 4: Customize the Watermark Position

The watermark position can be adjusted using margins:
 

imagecopy($im, $watermarkImg, imagesx($im) - $sx - MARGIN_RIGHT, imagesy($im) - $sy - MARGIN_BOTTOM, 0, 0, $sx, $sy);

Step 5: Test the Code

Upload images through your form and check if the watermark is added correctly.