Php：当使用正则表达式在html中存在多个img标记时，如何用不同的不同内容替换src

I get html content from ckeditor and i have following html content

<p><strong>Hello</strong></p>
<p><img alt="" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABVYAAAMACAIAA" style="height:131px; width:234px" /></p>
<p><strong>How are you</strong></p>
<p><img alt="" src="data:image/png;base64,ABAXKuVAAAAA3NCSVQICAjb4U/gAAAgAElEQV" style="height:142px; width:253px" /></p>
<p><strong>Good Morning</strong></p>
<p>&nbsp;</p>

Now i want to replace src of each image tag with different image name. Let says for example

<p><strong>Hello</strong></p>
<p><img alt="" src="img.jpg" style="height:131px; width:234px" /></p>
<p><strong>How are you</strong></p>
<p><img alt="" src="test.jpg" style="height:142px; width:253px" /></p>
<p><strong>Good Morning</strong></p>
<p>&nbsp;</p>

source of image is dynamically bind. so it can be anything.after this replacement i save this html content to database.

i have done with

$image_name ='<p><strong>Hello</strong></p>
    <p><img alt="" src="img.jpg" style="height:131px; width:234px" /></p>
    <p><strong>How are you</strong></p>
    <p><img alt="" src="test.jpg" style="height:142px; width:253px" /></p>
    <p><strong>Good Morning</strong></p>
    <p>&nbsp;</p>';
    $html = preg_replace('!(?<=src\=\").+(?=\"(\s|\/\>))!', 'img.jpg',$image_name );

But this replace all src same.

I want whole content same except src of <img> tag. I need to replace this content using regex. I prefer regex because i want to save this replaced html into database. If any other solution works then that is also good.

I have done using DOM parser as suggestion given in comments. Following is my so

$image_name = '<p><strong>Hello</strong></p>
<p><img alt="" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABVYAAAMACAIAA" style="height:131px; width:234px" /></p>
<p><strong>How are you</strong></p>
<p><img alt="" src="data:image/png;base64,ABAXKuVAAAAA3NCSVQICAjb4U/gAAAgAElEQV" style="height:142px; width:253px" /></p>
<p><strong>Good Morning</strong></p>
<p>&nbsp;</p>';

$doc = new DOMDocument();
$doc->loadHTML($image_name);
$img_tags = $doc->getElementsByTagName('img');

$i=0;
foreach ($img_tags as $t )
{
    $savepath = 'img_'.$i.'jpg';
    $t->setAttribute('src',$savepath);
    $i++;
}
$cont = $doc->saveHTML();

This gives me proper result.