Can you help increase my indexed images for my website

Hi,

I have about 5500 images on my ecommerce website http://www.ecustomfinishes.com all with alt text. I have 2 image sitemaps ( one for images and one that has images and pages) and combined only 466, or less than 10% of my images are indexed. Can you please give any advice on how to get more images indexed?

Here is a screen shot to my GWMT:
http://imgur.com/fgPDWPz

thank you
chris