We have a lot of Google Image visits in the external websites panel.

Here is what I notice in the external website panel:

• The visits come from all the different Google TLDs (.com, .co.uk, etc..)
• All these visits have the pattern www.google.{xxx}/imgres?
• All these visits have the keyword parameter missing

At the same time in our "Search Engines & Keywords" view:

• Some Google Images are tracked
• All the Google Images visits have keywords
• There is no "Keyword not defined" value

IMHO: All the Google Images visits without keyword are registered as external website.

Reproducing such URLs in Google Image is quite easy:

1. Go to google image:

www.google.fr/imghp?hl=en&tab=ii

2. Search the following keyword: "my_research_keywords"

www.google.fr/search?
tbm=isch&
hl=en&
source=hp&
biw=1680&
bih=925&
q=my_research_keywords&
gbv=2&
oq=my_research_keywords&
aq=f&aqi=&aql=&
gs_sm=12&
gs_upl=7086l7086l0l7492l1l1l0l0l0l0l83l83l1l1l0&
gs_l=img.12...7086l7086l0l7492l1l1l0l0l0l0l83l83l1l1l0

3. Click on the first image:

www.google.fr/imgres?
hl=en&
biw=1680&
bih=925&
gbv=2&
tbm=isch&
tbnid=kBma1eg8aVOKoM:&
imgrefurl=http://www.squido.com/research-keywords&docid=YSY3GQh3O8dkjM&
imgurl=http://i3.squidocdn.com/resize/squidoo_images/590/draft_lens10233921module148408128photo_1298307262Research_keywords_6.jpg&
w=590&h=412&
ei=_OVZT4_3EInQ8gOWuqXbDg&
zoom=1&iact=hc&vpx=164&vpy=205&dur=33&hovh=188&hovw=269&tx=137&ty=89&
sig=113944581904793140725&
page=1&tbnh=109&tbnw=156&start=0&
ndsp=42&ved=1t:429,r:0,s:0

Here the site is loaded in a new page without any search keyword.
Keywords: Google Image imgres