Apple makes extensive use of blur on iOS/MacOS to guide the users focus and attention. As announced in the 2019 roadmap, Flutter wants to expand to platforms beyond mobile (such as Mac/Web) but still wants to provide the most native experience possible. This could be easily improved by providing a more open ImageFilter API to give developers the power to customize blur effects.

In order to add a iOS like blur effect in CSS, apple is using the backdrop-filter: blur(20px) saturation(180%) property. It´s particulary important to have control over the saturation to achive a high similarity to the iOS/MacOS translucency.

No saturation:

With saturation:

Most of the effects defined in UIBlurEffect.Style could be recreated when providing a saturation filter.

Similar issues like this by @matthew-carroll
or this question on stackoverflow show that these APIs are requested for a long time. I am curious if the Flutter team is currently working on improving blur and how those APIs would look like since Hummingbird needs support for this as well.