I need to export icons for an android app in 4 different sizes: 36x36, 48x48, 64x64 and 72x72 px. The original size of icon I've created has size 272x272 px.
For example, see this image:
Left one is original size. The other two are scaled down but when exported, they have blur edges
Now, what I've always done is scaling them down and exporting one by one as PNG with size I need. But there's a problem. Some of the edges in each icon get blur. They are not crisp. However my original icon, when exported for testing, (272x272) is crisp.
What is the right way (if any) to get crisp edges for each icon size that I export?
PS: One way is to create each icon in separate file with size exactly that I need and align it to pixel grid. But that would need me to create a new icon every time I need a different size. If that's the only way to do this, I would do it, but do professional designers really do like this? e.g., you can see f of Facebook logo. It's crisp on every device. So is it the reality that they design each size individually for same logo?