formatting horizontal and vertical images in Settings?

I would not alter the core intermediate image sizes. If you have custom image sizes, register them using add_image_size(). e.g.

function mytheme_add_custom_image_sizes() {
     // Add "vertical" image
    add_image_size( 'vertical-a', 95, 117, true );
    add_image_size( 'vertical-b', 130, 160, true );
    // Add "horizontal" image
    add_image_size( 'horizontal-a', 440, 304, true );
    add_image_size( 'horizontal-b', 220, 152, true );
    // Add "home" image
    add_image_size( 'home', 260, 160, true )
}
add_action( 'after_setup_theme', 'mytheme_add_custom_image_sizes' );

Now, your registered custom image sizes can be used in any of the core image-related functions, to return the image in one of your custom sizes.