The EWWW Image Optimizer plugin is a commonly used plugin and service for optimizing images on your WordPress website. The plugin includes a large number of constants that can be defined in your site’s wp-config.php file.
EWWW Image Optimizer Plugin
If you want to enable the native lazy loading in the EWWW Image Optimizer plugin, then you can use this constant;
define( 'EIO_ENABLE_NATIVE_LAZY', true );
To disable the lazy loader auto-scaler, you can use this constant;
define( 'EIO_LL_AUTOSCALE', false );
To load the lazysizes.js file in the header rather than the footer, then use this constant;
define( 'EIO_LL_FOOTER', false );
To disable the check for JPG to PNG image conversion, then use this constant;
define( EWWW_IMAGE_OPTIMIZER_JPG_TO_PNG', false );
To preserve metadata and stop it from being removed during image optimization of images then, use this constant;
define( 'EWWW_IMAGE_OPTIMIZER_METADATA_REMOVE', false );
WordPress in version 4.5 decreased the JPG image quality from 90 to 82. To define a specific image quality level for JPG images when image optimized, then set this constant and adjust as needed;
define( 'EWWW_IMAGE_OPTIMIZER_JPG_QUALITY', 90 );
Knowing all the constants that the EWWW Image Optimizer plugin supports will make it easy to understand how to disable and enable specific features within the plugin.