Image sizes are huge! Any way to include optimization settings?

[trycatchdonothing]

First of all this tool is very helpful in generating all the image sizes needed for an app. The problem is, the output sizes for PNGs are huge (1.17MB+)! I had to re-export all the images using Photoshop with the PNG-8 setting. So, if an optimization setting can be added, it would be very helpful in reducing files sizes by 50% or more.