@RomainPiel ok cool, I was mistaken is actually IN which is just αA*αB, so instead of `Math.min()` you could use something like:

```java
MAX_ALPHA = 255;
targetAboveAlpha = (mAboveAlpha * alpha) / MAX_ALPHA;
mAbovePaint.setAlpha(targetAboveAlpha);
```

We should check boundaries (0 <= targetAboveAlpha <= 255) as docs read:

```
 Results are undefined if the alpha value is outside of the range [0..255]
```

And also check current `mAlpha != alpha` to save some ops