how to change image opacity within Image() widget – flutter

So am trying to change image opacity using the opacity property i found in Image() widget, this is a short code to be clear :

Padding(
            padding: EdgeInsets.all(10.0),
            child: Center(
              child: ClipRRect(
                borderRadius: BorderRadius.circular(15),
                child: Image(
                  image: NetworkImage(challengeImage),
                  fit: BoxFit.cover,
                  height: 150,
                  width: 350,
                  opacity: //not sure how to use
                ),
              ),
            ),
          ),

the image is a network image i retrieved from Firestore and am not sure what is the value i should put if its not double in order to apply opacity on the image. i thought to create a stack and insert asset image as a layer above my image and use the filter property but i would really like to know how the opacity can work with my code above, Thank you.

>Solution :

You can use AlwaysStoppedAnimation or create an Animation<double>

Image(
  image: NetworkImage(""),
  opacity: AlwaysStoppedAnimation(.1),
),