[repilo]

When I want a single image on a page I use the following styles.
To centre the image vertically, depending on its height I use a class that has the appropriate top margin (alone00 for none, alone10 por 10%, etc).

figure { margin:1em auto; padding:0; text-align:center; }
img { border:0; margin:0; padding:0; width:100%; }
figcaption { 
	margin:0; padding:.4em 0 .3em; text-align:center;
	text-indent:0; font-size:.82em; font-family:sans-serif;
}

figure.alone00 { page-break-before:always; margin-top:0; margin-bottom:0; }
figure.alone10 { page-break-before:always; padding-top:10%; page-break-after:always; }
figure.alone20 { page-break-before:always; padding-top:20%; page-break-after:always; }

  <p>Text.</p>

  <figure class="alone00">
    <img alt="" src="../images/1.jpg" />

    <figcaption><b>Fig. 1:</b> Text.</figcaption>
  </figure>

  <p>Text.</p>