Retina JS not working

The documentation for Retina JS states that images need to have the data-rjs attribute set in order for them to opt in to using the script. This can be done using the third parameter of get_the_post_thumbnail() : <?php echo get_the_post_thumbnail( get_the_ID(), ‘thumbnail’, array( ‘data-rjs’ => ‘3’ ) ); ?>

Create image formats with different qualities when uploading

1) A workaround by extending the WP_Image_Editor_GD class The problem is how to access the image sizes before we change the quality of intermediate jpeg images. Note that the image_resize() function is deprecated. We can use the jpeg_quality filter from the public get_quality method of the abstract WP_Image_Editor class: $quality = apply_filters( ‘jpeg_quality’, $quality, ‘image_resize’ … Read more