Imageapi Optimize - enabled libraries exec I'm investigating Imageapi Optimize module and everything is quite clear except one thing. There is a list of internal libraries on UI which can be enabled and set the order of it. So, for example if first library is set to pngquant and second is optipng and both are enabled, what does the second one do? 



I assume, when the image is being displayed pngquant process the image and it's being compressed. After the compression the image already have the desired size, so what does the second one do? I've searched through all the web and the module code and I can't really find out what is the logic behind it. I suppose it should be radio buttons rather then checkboxes.
so what does the second one do?


It'll optimise the already-optimised image from the previous plugin as best as it can. Which won't be much.


  I suppose it should be radio buttons rather then checkboxes.


Perhaps; but that would remove the ability to have combinations of different kinds of plugins (not just file size optimisers) in the future, so it might be a bit short-sighted to say that.