How to change compression of Wordpress uploads including original image

Question

We are currently using this to change the compression used on jpgs when uploaded to the WP media library:

add_filter(‘jpeg_quality’, function($arg){return 75;});

However, this does not compress the original image. We sometimes need to display the original image on our website and this also needs to be compressed. How do we do this?

Thanks in advance for any help!

Answer 1

For compressing the uploaded image I wrote a simple code snippet that immediately overwrites a newly uploaded file with an image whose quality can be specified:

function wt_handle_upload_callback( $data ) {
    $image_quality = 30; // Change this according to your needs
    $file_path = $data['file'];
    $image = false;

    switch ( $data['type'] ) {
        case 'image/jpeg': {
            $image = imagecreatefromjpeg( $file_path );
            imagejpeg( $image, $file_path, $image_quality );
            break;          
        }

        case 'image/png': {
            $image = imagecreatefrompng( $file_path );
            imagepng( $image, $file_path, $image_quality );
            break;          
        }

        case 'image/gif': {         
            // Nothing to do here since imagegif doesn't have an 'image quality' option
            break;
        }
    }

    return $data;
}
add_filter( 'wp_handle_upload', 'wt_handle_upload_callback' );

Regarding the additional image sizes (just change the return value):

add_filter( 'wp_editor_set_quality', function( $quality ) { return 30; } );