This post originated from an RSS feed registered with Ruby Buzz by Eigen Class. Original Post: Object removal using seam carving, still fast Feed Title: Eigenclass Feed URL: http://feeds.feedburner.com/eigenclass Feed Description: Ruby stuff --- trying to stay away from triviality. Latest Ruby Buzz Posts Latest Ruby Buzz Posts by Eigen Class Latest Posts From Eigenclass

The content-aware image resizer I presented a few days ago has gotten somewhat popular and triggered some discussion on reddit largely centered around its speed relative to the LiquidRescale GIMP plugin and whether OCaml can be "as fast as C". Here follows some more information about this particular case, where some OCaml code is outperforming some C code by a 6X margin.

In order to make the comparison meaningful, I implemented the main feature LiquidScale had over my code, energy biasing for object removal and/or preservation.

Take this image*1

Apply this energy bias, which indicates that we want the third policeman from the left to be removed

Here's what you get:

Implementation choices, cache efficiency

Both implementations use essentially the same algorithm, the main difference being the data structure used to represent the image and the energy map.

The governing principle is: if different parts of the structure are accessed at different times, separate them and pack each one as densely as possible.