Transform HTML img element attributes

gistfile1.xslt

<!--
    Transform the img element attributes in an HTML file.

    Tuija Sonkkila 17.2.2013
-->

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">

	<xsl:output method="html" indent="yes"/>

	<xsl:template match="/ | @* | node()">
		<xsl:copy>
			<xsl:apply-templates select="@* | node()" />
		</xsl:copy>
	</xsl:template>
	
	
  <!--  
        Replace the blog site part of the URL to nothing, and append the file name with 'images/'.
        The idea is to include all images locally to an EPUB bundle.
  -->
	<xsl:template match="img[starts-with(@src, 'https://blogs.aalto.fi/suoritin/files')]">
		<xsl:variable name="f" select="replace(@src, 'https://blogs\.aalto\.fi/suoritin/files/\d{4}/\d{2}/(.*)', '$1')"/>
		<xsl:copy>
			<xsl:attribute name="src">
				<xsl:value-of select="concat('images/', $f)"/>
			</xsl:attribute>
			<xsl:copy-of select="@* except @src"/>
		</xsl:copy>
	</xsl:template>

</xsl:stylesheet>