Is SPIE proceedings publication a real scientific publication? I have some SPIE proceedings publications. However, in a scientific context does proceedings publication count as a publication?
The SPIE proceedings volumes are generally fairly loosely peer-reviewed conference proceedings volumes.  The quality of the peer-reviewing can vary depending on the organizers of each particular conference.  

People do cite papers from these volumes and they're indexed by some research databases including Scopus and Google Scholar, but not Thompson's Web of Science (at least not the last time I checked.)  Like any conference proceedings papers, you'll have to take some responsibility for deciding whether the material is good enough to be worth citing.    

You haven't explained exactly what you mean by "count as a publication."  Here are several answers:


Will tenure and promotion committees consider these as publications?  Probably not at the same level as publications in top-tier peer-reviewed journals, but they probably will be considered as conference proceedings papers.
Can you submit a paper for journal publication after publishing it in an SPIE volume?  Probably not, unless the journal paper is significantly expanded.  Publication in one of these volumes typically would count as "prior publication."  
Should you cite a paper from an SPIE conference proceedings volume?  Yes, if the paper has useful information.  Readers of your paper should generally be able to obtain these papers if they want to look into the references further.  
Is the SPIE a predatory publisher?  I doubt that anyone would argue that it is a predatory publisher.