[KPhotoAlbum] Selecting/tagging images by resolution

[Joe]

I am starting to use some photos for publication.  Only "high" 
resolution images are accepted.  For my camera, that's 7.1MP.
When I search for pictures to use, I would like to automatically 
eliminate from consideration any that were not taken at a sufficient 
resolution.

When I double click on an image, the annotations that display with the 
enlarged image show the resolution, but only for one picture at a time.

Is there a way to select all pictures that are n MP or more in size?  
Can I mass tag them with a resolution keyword or something similar - 
without having to look at them one by one?   I currently have almost 
20,000 photos with a lot more coming, so doing anything one by one would 
be operationally infinite.

I looked under Search and Exif Search and didn't find anything.

Any ideas would be appreciated.

Joe
kpa 4.1.1 kubuntu lucid