p:graphicImage value vs library

[vished]

Hi all,

I have in my topbar the following expression which give me the user picture from a user.
If there is no picture than i´m using the default.

My problem is now:
<p:graphicImage with library="morpheus-layout" is calling my function 3x

#{userPictureRequestController.getUserPicture_32_32(loginBean.currentUser) == null}

and
<p:graphicImage only with the value calls the function only 1x

<p:graphicImage name="images/profile-image.png"
rendered="#{userPictureRequestController.getUserPicture_32_32(loginBean.currentUser) == null}" cache="true"
library="morpheus-layout" />
<p:graphicImage
rendered="#{userPictureRequestController.getUserPicture_32_32(loginBean.currentUser) != null}" cache="true"
value="#{request.contextPath}/files/#{userPictureRequestController.picture32Path}" />

Any explanation?
Is there a better way to implement this?