image optimizer for web

I want to resize only the ratio maintenance + horizontal resolution.
And,
I want to resize only ratio maintenance + vertical resolution.

For example,
Resize
  □ Limit max width / height(resize) to
  [n pixels] keep ratio
↓
Resize
  □ Limit max width(resize) to [n pixels] keep ratio
  □ Limit max height(resize) to [n pixels] keep ratio

The current resize option is a very terrible feature for long vertical images (500×15000).

I feel the need to separate the horizontal and vertical resizes.