pentimento
...that a pentimento is an alteration to a painting that can often only be seen in an X-ray or an infra-red photograph?
...that a <b id="mwDFA"><a href="./Pentimento" id="mwDFE" rel="mw:WikiLink" title="Pentimento">pentimento</a></b> is an alteration to a <a href="./Painting" id="mwDFI" rel="mw:WikiLink" title="Painting">painting</a> that can often only be seen in an <a href="./X-ray" id="mwDFM" rel="mw:WikiLink" title="X-ray">X-ray</a> or an <a class="mw-redirect" href="./Infra-red" id="mwDFQ" rel="mw:WikiLink" title="Infra-red">infra-red</a> <a href="./Photograph" id="mwDFU" rel="mw:WikiLink" title="Photograph">photograph</a>?