changing generated html for images from the_content

I want images on my pages & posts to not have height and width declarations in the html. How can I strip this code from the_content?

this is my page.php code:

<?php get_header(); ?>
<?php while (have_posts()) : the_post(); ?>
  <?php the_content(); ?>
<?php endwhile;
get_footer(); ?>

this is the relevant generated code for one page:

<p><a href="https://alexandrarothwell.com/wp-content/uploads/2011/04/blueyeller.jpg"><img class="aligncenter size-large wp-image-117" title="blueyellerreal" src="https://alexandrarothwell.com/wp-content/uploads/2011/04/blueyellerreal-239x800.jpg" alt="" width="239" height="800" />
</a></p>
	<h1>ventilator blues</h1>

so how can i get rid of the width and height text?

Thanks!!!