public void LoadPNG(string filePath, Button btn)
    {

        Texture2D tex = null;
        byte[] fileData;

        if (File.Exists(filePath))
        {
            fileData = File.ReadAllBytes(filePath);
            tex = new Texture2D(2, 2);
            tex.Apply();
            Sprite img = Sprite.Create(tex, new Rect(0.0f, 0.0f, tex.width, tex.height), new Vector2(0.5f, 0.5f), 100.0f);
            btn.image.sprite = img;

            //tex.LoadImage(fileData); //..this will auto-resize the texture dimensions.
        }

        else
            Debug.LogError("Could't load thumbnail image from streaming assets.");



    }