If you resize picture by defining new width or height from normal size, you will get the picture resolution's distorted or broken quality. There's a method how to make the picture keeps soft and smooth.

Create a utility class

package com.jackBite.utils
{
  import mx.controls.Image;
  import flash.display.Bitmap;

  public class CleanImage extends Image
  {
    /*public function CleanImage()
    {
    }*/
    
    override protected function updateDisplayList(unscaledWidth:Number,unscaledHeight:Number):void
    {
      super.updateDisplayList(unscaledWidth, unscaledHeight);
      if(content is Bitmap)
      {
        var bmp:Bitmap = Bitmap(content);
        if(bmp && bmp.smoothing == false)
          bmp.smoothing = true;
       }
    }

  }
}

  <utils:CleanImage id="feedLogo" height="30" source="{_imageRss}"/>