Question

Switching H1 text with a logo image

Answer 1

<h1>
  <a href="http://stackoverflow.com">
    <img src="logo.png" alt="Stack Overflow" />
  </a>
</h1>

you missed this option 

or try this solution 

<h1 id="logo">
  <a href=""><span>Stack Overflow</span></a>
</h1>

/* position code, it may be absolute position or normal - depends on other parts of your site */
#logo {
  ...
}

#logo a {
   display:block;
   width: actual_image_width;
   height: actual_image_height;
   background: url(image.png) no-repeat left top;
}

/* for accessibility reasons - without styles variant*/
#logo a span {display: none}