Change featured image size on a specific archive page in Genesis

functions.php

// Change featured image size on a specific archive page
function sjd_custom_loop_image_size( $image_size ) {
	if(is_archive('testimonial')){
		$image_size = 'content-slider';
		return $image_size;
	}
}
add_filter( 'genesis_pre_get_option_image_size', 'sjd_custom_loop_image_size' );