Image Compression Case Study: ImageOptim vs. Xcode

When iOS developers package their apps, images can be compressed to a “CgBi” format through Xcode that helps reduce the total application size and improve performance. Compression, however, could be taken a lot further. In ImageOptim’s case study, they took a look at TweetBot for the iPad, a graphically rich application that contains over 26 MB of compressed images. When ImageOptim optimized the uncompressed versions of those images through their application, and twice over in combination with ImageAlpha, they saw a dramatic reduction in file size and loading times.

Disabling Xcode conversion and simply using ImageOptim instead was enough to reduce the application size by almost 30% (33.4MB down to 23.8MB) and halve initial display time in the benchmark.

Manually optimizing images with ImageAlpha reduced entire application size by more than a half (33.4MB down to 16.3MB). Images alone were 65% smaller and were displayed 2.5 times quicker than Xcode-optimized ones.

ImageOptim claims that developers can submit applications that don’t use Xcode’s compression method, point to resources showing how this can be done, and also link to an excellent success story. Developers should definitely check out the examples and data provided on their blog post to see how they can better optimize their apps. [ImageOptim via @cbowns]