Hi Doug
Rob is away for a week or so and would normally respond. I'll jump in while he's away. I believe the 'Rating' applies only to competition entries and is (I think) the average score given by those voting on the image.
While I'm on the subject, another one that seems to cause confusion is the 'High Quality' entry against an image in the 'My Images' pages. I understand this was the result of scoring conducted by assessors when images were being considered for the Premier Bird Images Gallery. Note that the PBIG process still has to get to most of the images in the database so very few images are likely to have this rating. The following quote from the description of the PBIG gallery explains (see second para especially):
"In 2015 there are two Working Groups appraising the existing images in our library, working through the thousands of images in family groups. Each WG consists of three experienced photographers; several of these photographers have won national and international awards for their photography. Whilst the judging of images will always have a subjective component, images are judged by reference to standards such as the Photographic Exhibitions Committee of the Professional Photographers of America. Images are scored out of a total of 15 points and those images with a score of 14 or 15 are identified for transfer to the PBIG. A score of 15/15 is judged as excelling in all the key criteria that an individual judge ascribes to an image of the highest quality. A 14/15 image may have one deficiency in a critical element that removes it from the 15/15 category but still scores the image in the second highest tier.
The Committee has decided that an individual photographer may only have a total of 3 images of a species in the PBIG. Where a photographer has more than 3 images for any one species, images selected for transfer to the PBIG will be referred back to the appropriate WG for final selection. In special circumstances, the BirdLife Photography Committee may allow more than 3 but no more than 5 images for an individual species from any one photographer. Where images with a score of 14 or 15 have been excluded on the basis of the species limit, these images will remain in their original gallery and will be identified by a 'High Quality' flag; you can search for these images by using the Filter facility in our galleries."