code: public void setFormat(CmsObject cms, String format) {
  
          if (CmsStringUtil.isEmptyOrWhitespaceOnly(format)) {
              m_format = "";
              if (m_element.element(PARAM_FORMAT) != null) {
                  m_element.remove(m_element.element(PARAM_FORMAT));
              }
          } else {
              m_format = format;
          }
          setParameterValue(cms, PARAM_FORMAT, format);
      }
docs: Sets the format information of the image.<p>
  
  @param cms the current users contexts
  @param format the format information of the image