As per the title, I have a RGB photo and I'm trying to get three separate grayscale images, each one referring to a single channel (i.e., a grayscale image for R, G and B values).

From what I've read I should just make two channels invisible and simply export, but that's not working for me - I get the colored, three channels pic again. Thank you.


Question: Get an IFRAME element by name does not work anymore?
Answer: because you haven't set the id but name try this:

window.document.getElementByName("frameModalityList")


or insert the id into the html:

&lt;iframe id="frameModalityList" name="frameModalityList" src="iframe_advanced_list.jsp" frameborder="0" marginheight="0" marginwidth="0" class="advanced_list" width="100%" height="300"&gt;&lt;/iframe&gt;

window.document.getElementById("frameModalityList")