The original files corresponding to these binary masks (with the same file name) can be obtained from the URL provided in:

Z. Wang and B. Li. A two-stage approach to saliency detection in images. ICASSP 2008.

UPDATE:

The URL in the paper seems to be no longer valid. The original images can be found at the following URL:

http://research.microsoft.com/en-us/um/people/jiansun/SalientObject/salient_object.htm