How to make Image transparency with jetpack compose?

Image( painter = image,

contentDescription = "image",

contentScale = ContentScale.FillHeight,

modifier = Modifier.fillMaxHeight(),

alpha = 0.2f )

package com.example.jetpack

import android.os.Bundle
import android.view.WindowManager
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.Image
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.painter.Painter
import androidx.compose.ui.layout.ContentScale
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.sp
import com.example.jetpack.ui.theme.JetPackTheme

class MainActivity : ComponentActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        window.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE)
        setContent {
            MaterialTheme {
                // A surface container using the 'background' color from the theme
                Surface(color = MaterialTheme.colors.background) {
                    ImageTransparency()
                }
            }
        }
    }
}

@Composable
fun ImageTransparency() {
    val image: Painter = painterResource(id = R.drawable.image_trans)
    Box(content = {
        Image(
            painter = image,
            contentDescription = "image",
            contentScale = ContentScale.FillHeight,
            modifier = Modifier.fillMaxHeight(),
            alpha = 0.2f
        )
        Column(content = {
            Text("Image with transparency",color = Color.Black,fontSize = 30.sp,fontWeight = FontWeight.Bold)  },verticalArrangement = Arrangement.Center,horizontalAlignment = Alignment.CenterHorizontally,modifier = Modifier.fillMaxSize())
    })
}