Image gallery with original image proportions
You most probably want the functionality provided by Masonry API and its sub-modules: Masonry Views and Masonry Fields.


  Masonry is a dynamic grid layout plugin for jQuery. Think of it as the
  flip-side of CSS floats. Whereas floating arranges elements
  horizontally then vertically, Masonry arranges elements vertically,
  positioning each element in the next open spot in the grid. The result
  minimizes vertical gaps between elements of varying height, just like
  a mason fitting stones in a wall.


In the view you will specify a image formatter that only sizes on the width so that the height remains proportional.