rdtran,
I had a similar question and bwasnie1 helped me to discover that I should use “data” instead of “params”.
The PHP part came from other sites (don’t have the links anymore)
It took me some time to gather all the information and solve that issue. 
The only one thing I could not resolve yet is the size of the base64 image. Even if I set the height and width to 100 and quality to 5 in the ngcordova options, the image size is veeeeery big (still 1.6MB and . It maybe right because the conversion will multiply the base image by 4 (I think), but MySql seems to think it is a bit too big (still working on that problem)
Maybe it is because I am using a Blackberry 10? I would doubt, but I am not an expert. Still need some investigation or maybe I will use the file (FILE_URI) instead of the url (DATA_URL).