gistfile1.txt

add_filter( 'get_image_tag', function( $html, $id, $alt, $title, $align, $size ){
    $original_url = $this->get_original_url( $id );
		if ( ! $original_url ) {
			return $html;
		}
    list( $img_src, $width, $height ) = image_downsize( $id, $size );
    $hwstring                         = image_hwstring( $width, $height );
    $html = '<img src="' . $img_src . '" alt="' . esc_attr( $alt ) . '" ' . $title . $hwstring . 'class="' . $class . '" />';
 
    
  return $html;
});

public function get_image_tag( $html, $id, $alt, $title, $align, $size ) {
		// Verify it is an Unsplash ID.
		$original_url = $this->get_original_url( $id );
		if ( ! $original_url ) {
			return $html;
		}

		// Replace img src.
		list( $img_src ) = image_downsize( $id, $size );
		return preg_replace( '/src="([^"]+)"/', "src=\"{$img_src}\"", $html, 1 );
	}