Ionic header bar with title image - image scaling

Ionic v4 and Angular 8 with Capacitor. I have a header bar with a title image that is working. Problem is I cannot get the image to scale to the header height automatically. Any help?

<ion-header>
  <ion-toolbar color="primary" mode="ios">
    <ion-title>
        <img src="../assets/icon/logo-header_sm.png" class="ion-header">
    </ion-title>
  </ion-toolbar>
</ion-header>
.ion-header{
    margin-left: auto;
    margin-right: auto;
    text-align: center;
    height: auto;
}