Using WordPress ‘load_image_to_edit’ PHP filter

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The load_image_to_edit WordPress PHP Filter allows you to modify the image being loaded for editing in the WordPress media library.

Usage

add_filter('load_image_to_edit', 'your_custom_function', 10, 3);

function your_custom_function($image, $attachment_id, $size) {
    // your custom code here
    return $image;
}

Parameters

  • $image (resource|GdImage) – The current image being loaded.
  • $attachment_id (int) – The ID of the attachment.
  • $size (string|int[]) – The requested image size. It can be any registered image size name, or an array of width and height values in pixels (in that order).

More information

See WordPress Developer Resources: load_image_to_edit

Examples

Watermarking Images

Add a watermark to the image when it is loaded for editing.

add_filter('load_image_to_edit', 'apply_watermark', 10, 3);

function apply_watermark($image, $attachment_id, $size) {
    // Load watermark image
    $watermark = imagecreatefrompng('path/to/watermark.png');

    // Apply watermark to the image
    imagecopy($image, $watermark, 0, 0, 0, 0, imagesx($watermark), imagesy($watermark));

    // Free memory associated with watermark
    imagedestroy($watermark);

    return $image;
}

Adjust Image Brightness

Increase the brightness of the image when it is loaded for editing.

add_filter('load_image_to_edit', 'adjust_brightness', 10, 3);

function adjust_brightness($image, $attachment_id, $size) {
    // Increase brightness by 20
    imagefilter($image, IMG_FILTER_BRIGHTNESS, 20);

    return $image;
}

Convert Image to Grayscale

Convert the image to grayscale when it is loaded for editing.

add_filter('load_image_to_edit', 'convert_to_grayscale', 10, 3);

function convert_to_grayscale($image, $attachment_id, $size) {
    // Convert image to grayscale
    imagefilter($image, IMG_FILTER_GRAYSCALE);

    return $image;
}

Resize Image Proportionally

Resize the image proportionally to fit within a specified width and height when it is loaded for editing.

add_filter('load_image_to_edit', 'resize_proportionally', 10, 3);

function resize_proportionally($image, $attachment_id, $size) {
// Set the desired width and height
$desired_width = 300;
$desired_height = 200;

// Calculate new dimensions
$original_width = imagesx($image);
$original_height = imagesy($image);
$aspect_ratio = $original_width / $original_height;

if ($desired_width / $desired_height > $aspect_ratio) {
$desired_width = $desired_height * $aspect_ratio;
} else {
$desired_height = $desired_width / $aspect_ratio;
}

// Create a new image with the new dimensions
$new_image = imagecreatetruecolor($desired_width, $desired_height);
imagecopyresampled($new_image, $image, 0, 0, 0, 0, $desired_width, $desired_height, $original_width, $original_height);

// Free memory associated with the original image
imagedestroy($image);

return $new_image; 

}

Apply a Custom Filter

Apply a custom filter to the image when it is loaded for editing.

add_filter('load_image_to_edit', 'apply_custom_filter', 10, 3);
function apply_custom_filter($image, $attachment_id, $size) {
// Define a custom filter matrix
$filter_matrix = [
[-1, -1, -1],
[-1, 8, -1],
[-1, -1, -1]
];

// Apply the custom filter to the image
imageconvolution($image, $filter_matrix, 1, 0);

return $image;
}